Abstracts with displays | EXOA

Abstract

High-precision measurements of isotopes in meteorites suggest that the early population of small bodies in the Solar System has been separated into two reservoirs by the forming Jupiter, acting as a radial barrier for these 'planetesimals' [1]. In a proposed Jupiter formation scenario [2], the solid core must grow within 1 Myr to around 20 Earth masses, then stagnate its growth for 2-3 Myr and thus separating the planetesimal reservoirs, and finally grow to the final Jupiter mass stirring and mixing the inner and outer planetesimals. The fast and early core growth is efficiently facilitated by the accretion of small 'pebble-like' objects. In order to delay the otherwise inevitable rapid runaway gas accretion for an extended period of time after the pebble accretion stops, Jupiter is proposed to be heated by slower planetesimal accretion before finally becoming massive enough to accrete a large amount of gas, reaching its present day mass.

Motivated by this proposed formation scenario of Jupiter, we investigate the consequences of a combined pebble and planetesimal accretion model for the formation of giant planets and planet formation in general [3]. We modify the Bern model of planetary population synthesis [4] with a simple model of pebble formation and accretion [5]. In a single-planet population synthesis approach, we run the model on a thousand different initial protoplanetary disks in order to probe the effects of the two solid accretion mechanisms on a population level. To uncover the interplay of the two models, we vary the amount of pebbles with respect to planetesimals.

As shown in figure 1, it proves to be difficult to form giant planets from the accretion of pebbles and planetesimals whereas both mechanisms individually are able to form giants in suitable disks. We identify the remaining accretion of planetesimals after the stop of pebble accretion to be crucial for the formation pathway of a growing planet. The envelope heating due to the accretion of solids is shown to play a critical role for the accretion of gas. A combination of enhanced inward orbital migration and delayed runaway gas accretion strongly suppresses the formation of giants in disks containing both pebbles and planetesimals.

Figure 1: Planet mass over semi-major axis snapshot after 2 Gyr of evolution for populations of one thousand disks, containing one planet. The four, otherwise identical, populations start with either only planetesimals (left), 30% pebbles (middle left), 70% pebbles (middle right), or only pebbles (right).

References

[1] Kruijer T. S., Burkhardt C., Budde G., Kleine T., 2017, Proc. Natl. Acad. Sci., 114, 6712

[2] Alibert Y., Venturini J., Helled R., et al., 2018, Nature Astronomy, 2, 873

[3] Kessler A., et al., in prep.

[4] Emsenhuber A., Mordasini C., Burn R., et al., 2021, A&A, 656, A 69 

[5] Bitsch B., Lambrechts M., Johansen A., 2015b, A&A, 582, A 112

How to cite: Kessler, A., Alibert, Y., Mordasini, C., Emsenhuber, A., and Burn, R.: Giant Formation with Pebbles and Planetesimals, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-114, https://doi.org/10.5194/epsc2022-114, 2022.

The size distribution of solids in the protoplanetary disk is still ill constrained [1] but is a vital parameter that influences planetary growth [2]. The typical size and spatial distribution of solids evolves throughout the planet formation process via collisions and radial drift. As the planets grow, they excite the mutual random velocities among planetesimals making their mutual collisions destructive which leads to fragmentation, reducing their typical size. This effect of self-interacting planetesimals has been found to inhibit or favor the formation of planets due to competing effects of easier accretion of smaller fragments and depletion by gas-drag induced drift [3-4]. However, previous studies have either focused on single planets and systems or have neglected concurrent effects like migration.

Therefore, we run planet formation simulations with the generation III Bern model [5] with a Eulerian 1D solid disks. The model tracks the growth and evolution of several planetary embryos from oligarchic growth to the final planetary system. We added to it a fragmentation toy model [6] to see the impact fragmentation has on planet formation. To see its influence on the diverse types of exoplanets we make use of a population synthesis approach to investigate larger parts of the parameter space [7]. This allows us to have a more complete picture of what influence the collisional evolution of planetesimals has on planet formation and to study the effects that arise from its interplay with the formation of multiple planets in the same system.

In figure 1, we show two exemple synthetic planet populations of 1000 systems with (right) and without (left) the added fragmentation model. We find multiple interesting features in our synthetic populations that arise from the fragmentation of planetesimals. The fragmentation lends more importance to specific locations in the disk where growth is enhanced like the ice line and the inner disk. In addition, it enhances the formation of giants.

In conclusion, there are significant differences in synthetic populations when including or neglecting fragmentation. This suggests that the addition of fragmentation to global planet formation models is important as a self-consistent solid disk description is vital to understand planet formation.

In figure 1. Comparison of a synthetic exoplanet population without (left) the added fragmentation model and one with (right).  The semi major axis (in AU – log scale) is plotted on the x-axis and the planetary mass (in Earth masses – log scale) on the y-axis. Both populations are shown at an age of 5 Gyr. The Red points refer to planets with more envelope than core mass, the blue ones are icy planets (ice mass fraction larger than 1%) and the green points are rocky planets (ice mass fraction smaller than 1%).

References:

[1] Helled, R. & Morbidelli, A. 2021, in ExoFrontiers (IOP Publishing)

[2] Fortier, A., Alibert, Y., Carron, F., Benz, W., & Dittkrist, K.-M. 2012, A&A, 549, A44

[3] Guilera, O. M., de Elía, G. C., Brunini, A., & Santamaría, P. J. 2014, A&A, 565, A96

[4] Chambers, J. 2008, Icarus, 198, 256

[5] Emsenhuber, A., Mordasini, C., Burn, R., et al. 2021, A&A, 656, A69

[6] Ormel, C. W. & Kobayashi, H. 2012, The Astrophysical Journal, 747, 115

[7] Emsenhuber, A., Mordasini, C., Burn, R., et al. 2021b, A&A, 656, A70

How to cite: Kaufmann, N. and Alibert, Y.: A population level study on the influence of planetesimal fragmentation on planet formation, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-135, https://doi.org/10.5194/epsc2022-135, 2022.

Although most stars exist in binary and multi systems, very few circumbinary planets (CBP) have been identified and studied. Observational biases contribute significantly to this paucity, as the orbital regions close to binaries are often unstable due to overlapping secular resonances. As we continue to improve our data reduction and analysis techniques, we can start to detect more planets farther from their stars and will therefore detect more CBPs. Through thousands of N-body simulations, we constrain the stability regions of an injected terrestrial planet around low-mass binaries, integrating the systems for 1Gyr or until instability. We then explore the potential detection and habitability of such planets. Through the 1Gyr evolution of the system, we trace the top-of-atmosphere temperature of the simulated planets to constrain the fraction that could host liquid water on their surfaces. Then, using a simple energy-balance model, we study the evolution of the planets' surface temperatures to identify which could host regions of continuous surface water.

How to cite: MacDonald, M. and Pedowitz, M.: Constraining the stability and habitability of circumbinary planets, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-164, https://doi.org/10.5194/epsc2022-164, 2022.

The sailboat region was first identified by Giuliatti Winter, et al. (2010) exploring the Pluto-
Charon binary system, they identifed this unexpected stable region of S-type orbits around the dwarf
planet Pluto located at a = (0.5d, 0.7d) and e = (0.2, 0.9), where a and e are the initial values
of semi-major axis and eccentricity of particles, respectively and d is the separation of the binary.
The sailboat is associated with a family ”BD” of periodic orbits derived from the planar, circular,
restricted three-body problem. In this work, we analyzed through numerical simulations the structure
and stability of sailboat in hypothetical systems with different values of mass ratio and for several
orbital configurations.
To constrain the orbital parameters for sailboat regions, we numerically simulated several elliptic
three-body problem, exploring a large range of initial conditions. We adopt dimensionless systems
and the configuration for each simulation include a test particle in S-type orbit around the primary
body and gravitational disturbed by the secondary massive body. We set the central body as a point
of mass and a secondary with a mass equivalent to the mass ratio of the binary system (µ), with its
radius (r s ) defined as 10% of their Hill radius.
We created hypothetical systems with different mass ratio in the interval µ = [0.01, 0.30] in steps
∆µ = 0.01. The test particles were randomly distributed with semimajor axis in a = [0.45, 0.7],
considering 1 the distance between the two main bodies, the eccentricities varied from 0 to 0.99, and
initially the argument of the pericentre and inclination was set as 0º. We numerically integrated using
the REBOUND package and IAS15 integrator (Rein & Spiegel 2014) for 10 4 orbital periods of the
binary.
We analyzed the behaviour of the sailboat according to the eccentricity e of the secondary body,
looking for the maximum value for which the particles remain stable. A final set of simulations was
performed for different values of inclinations and argument of pericenter in order to determine the
extreme values for the stability.
Our results show the sailboat is robust and it exists for µ = [0.01,0.27] and for large intervals
of the argument of pericentre and inclination. This region of stability reaches its maximum size
with an argument of pericenter at 0 ◦ and 180 ◦ . The sailboat region also is present for values of
inclination > 60º and existing even retrogrades orbits in the systems with µ > 0.08.
The numerical results also showed that little changes in the eccentricity of the secondary body is
sufficient to vanish the sailboat region, for binaries system with µ > 0.12, the sailboat exists just for
values of e < 0.05.

How to cite: Pinheiro, T., Sfair, R., and Vieira, E.: Study of the Sailboat stable region for binary systens., Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-759, https://doi.org/10.5194/epsc2022-759, 2022.

Circumplanetary disks are regarded as birthplaces of large moons. While Jupiter has four large satellites known as Galilean moons, Titan is the only large moon around Saturn. N-body simulations using a simple power-low disk suggest a system tend to have multiple moons or loses all the moons due to inward migration. Thus, forming a single satellite system in a disk is known to be difficult. 
 The orbits of moons are continuously affected by the interaction with the disk, and the direction and speed of the migration depend on the disk structures, i.e., surface density and temperature. Therefore, the final configuration of the moon system is determined during the dissipation of the disk. We studied the orbital evolution of moons in various circumplanetary disks to find a way of configuring a single-large-moon system. 
 We model dissipating circumplanetary disks with taking the effect of opacity into account when we calculate the temperature structure. Because of this, our disk has multiple slopes, and thus, the migration speed of a moon varies with the orbital location. Then, we calculate the orbital evolution of Titan-mass moons in the final evolution stage of the disks. We performed N-body simulations with initially many satellites to see whether single-moon systems can form at the end. 
 We found that the radial slope of the temperature structure characterized by the dust/ice opacity produces a patch of orbits where the Titan-mass moons resist inward migration with a certain range of the viscosity. We call such a patch as “safety zone.” The safety zone assists moons initially located in the outer orbits to remain in the disk, while those in the inner orbits migrate toward the planet. When the satellite formation is not very efficient in the outer radii of circumplanetary disks, the system can end up with a single large moon at a distant from the planet while the inner orbits are cleared out. Smaller moons may stay in the inner orbits as their migration speed is slower compared to the Titan-mass ones. We demonstrated the formation of systems with single large moon around gas giants for the first time. 

How to cite: Fujii, Y. and Ogihara, M.: Formation of a single large moon around a gas giant: Saturn-Titan system, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-806, https://doi.org/10.5194/epsc2022-806, 2022.

The protoplanetary disk (PPD) is a complex structure. It is the birth place of protoplanetary systems. The interaction of growing planets and its surrounding PPD is also complex and not fully understand by now. The many different physical processes going on in the PPD over its life time, like accretion, outbursts, planet formation, etc. impact its evolution and structure. The evolution of such a PPD with a growing planet, implemented as a sink term, is simulated by the TAPIR code.  It is an 1+1D implicit code. Due to the fact that TAPIR is an implicit code the time steps are not restricted by the CFL-conditions, therefore it is able to simulate over the whole lifetime of a PPD and examine the evolutionary behaviour of the protoplanetary disk and the influence of a forming protoplanet on it. The results show the gap formation due to mass accretion onto the planet and impact of this sink term on the total disk mass, disk lifetime and accretion rat onto the star. Also the impact of accretion bursts on the accretion rate of the planet is discussed. If the planet is placed in the dead zone the presence of outbursts leads to a quite faster planet growth since the bursts rearranges the disk structure.

How to cite: Ringseis, I.: Impact of growing planets on the evolution of protoplanetary disks, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-1104, https://doi.org/10.5194/epsc2022-1104, 2022.

In close exoplanetary systems, tidal interactions are known to shape the orbital architecture of the system, modify star and planet spins, and have an impact on the internal structure of the bodies through tidal heating. Most stars around which planets have been discovered are low-mass stars and thus feature a magnetised convective envelope, as is also expected in giant gaseous planets like Hot-Jupiter. Tidal flows, and more specifically inertial waves (restored by the Coriolis acceleration, and recently discovered in the Sun) tidally-excited, are the main direct manifestation of tidal interactions in the convective envelopes of these bodies. Furthermore, inertial waves are small-scale waves that are sensitive to nonlinearities, especially in close Hot-Jupiter systems with strong tidal forcing. The nonlinear self-interaction of inertial waves is known to trigger differential rotation in convective shells, as shown in numerical and experimental hydrodynamical studies. Since inertial waves are a key contribution to the tidal dissipation in close star-planet systems, it is essential to have the finest understanding of tidal inertial wave propagation and dissipation in such a complex nonlinear, magnetised, and differentially rotating environment.
In this context, we investigate how nonlinearities affect the tidal flow properties, thanks to new 3D hydrodynamic and magneto-hydrodynamic nonlinear simulations of tides, in an adiabatic and incompressible convective shell. First, we show to what extent the emergence of differential rotation is modifying the tidal dissipation rates, prior to linear predictions. In this newly generated zonal flows, nonlinear self-interactions of tidal inertial waves can also trigger different kind of instabilities and resonances between the waves and the background sheared flow, when the tidal forcing is strong enough or the viscosity low enough. These different processes disrupt the energetic exchanges between tidal waves and the background flow, and also further modifies the tidal dissipation rates. Secondly, we present the first non-linear numerical analysis of tidal flows in a magnetised convective shell. One main effect of the magnetic field in our model is to mitigate zonal flows triggered by the nonlinear interaction of inertial waves. The consequences for tidal flows are important, since the installation of zonal flows in nonlinear hydrodynamical simulations is the main cause of significant changes in tidal dissipation and angular momentum exchanges, compared to linear predictions for a uniformly rotating body. 

How to cite: Astoul, A. and Barker, A.: Nonlinear tidal interactions in the convective envelopes of low-mass stars and giant gaseous planets, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-1198, https://doi.org/10.5194/epsc2022-1198, 2022.

New ALMA observations of protoplanetary disks allow us to probe planet formation in other planetary systems, giving us new constraints on planet formation processes. Meanwhile, studies of our own Solar System rely on constraints derived in a completely different way. However, it is still unclear what features the Solar System protoplanetary disk could have produced during its gas phase. By running 2D isothermal hydro-simulations used as inputs for a dust evolution model, we derive synthetic images at millimeter wavelengths using the radiative transfer code RADMC3D. We find that the embedded multiple giant planets strongly perturb the radial gas velocities of the disk. These velocity perturbations create traffic jams in the dust, producing over-densities different from the ones created by pressure traps and located away from the planets’ positions in the disk. By deriving the images at λ = 1.3 mm from these dust distributions, we show that very high resolution observations are needed to distinguish the most important features expected in the inner part (<15 AU) of the disk. The traffic jams, observable with a high resolution, further blur the link between the number of gaps and rings in disks and the number of embedded planets. We additionally show that a system capable of producing eccentric planets by scattering events that match the eccentricity distributions in observed exoplanets does not automatically produce bright outer rings at large radii in the disk. This means that high resolution observations of disks of various sizes are needed to distinguish between different giant planet formation scenarios during the disk phase, where the giants form either in the outer regions of the disks or in the inner regions. In the second scenario, the disks do not present planet-related features at large radii. Finally, we find that, even when the dust temperature is determined self-consistently, the dust masses derived observationally might be off by up to a factor of ten compared to the dust contained in our simulations due to the creation of optically thick regions. Our study clearly shows that in addition to the constraints from exoplanets and the Solar System, ALMA has the power to constrain different stages of planet formation already during the first few million years, which corresponds to the gas disk phase.

How to cite: Bergez-Casalou, C., Bitsch, B., Kurtovic, N., and Pinilla, P.: Constraining giant planet formation with synthetic ALMA images of the Solar System's natal protoplanetary disk, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-85, https://doi.org/10.5194/epsc2022-85, 2022.

With the increasing observational capabilities of the young stars and their surrounding disks bringing new constraints on the planet formation process, planet formation theory is undergoing major changes. One of the significant paradigm shifts is the belief that the first planetary cores start forming early, possibly during the circumstellar disk buildup process.

I will review the current understanding of planet formation, including dust growth to pebbles, formation of the first gravitationally bound planetesimals, and the growth of planetary cores by accretion of planetesimals and pebbles. I will highlight the possible pathways to early planet formation, stressing that the planet formation process may not be spatially uniform in the disk and that there are preferential locations for the formation of the early planetesimals and planets, such as the water snow line or dust traps. 

How to cite: Drazkowska, J.: Theoretical perspective on early planet formation, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-259, https://doi.org/10.5194/epsc2022-259, 2022.

AB Aur is a bright and young Herbig Ae star surrounded by a broad transitional disk, with a long record of detailed observations at various wavelengths. Multiple direct and indirect evidences for the presence of embedded proto-planets have been reported in the recent years in this system. A prominent double spiral pattern was first detected with ALMA in the molecular line emission of CO gas, with a large pitch angle in the most inner region, suggesting the presence of at least one sub-stellar body within the cavity of the dusty disk (R<120au). We obtained two epochs of observations of AB Aur with VLT/SPHERE (Dec. 2019 - Jan. 2022). The first polarimetric image showed a wealth of structures at several scales. Two spirals clearly overlap those detected with ALMA, although with a higher angular resolution. One of these spirals features a twist located at 0.18’’ from the star, reminiscent of structures predicted by the theory of density waves produced by a gravitational perturber onto the gas distribution. The analysis of the multi-epoch data shows changes consistent with Keplerian rotation with a protoplanet located at about 30au from the star. In addition, localized emissions could be attributed to additional planet candidates (which are otherwise expected in order to carve the large disk cavity), including the recent claim of a super-Jupiter near 90au from high-contrast near-IR imaging with Subaru-SCexAO. All these pieces of evidence make AB Aur one of the most promising young sources to investigate planet-disk interactions, and to unveil the close environment of accreting planets. I will report on the global (and detailed) analysis of the new observational results for this nascent planetary system, both in the context of the multi-epoch, and multi-wavelength SPHERE+ALMA images, and with the contribution of multi-fluid hydrodynamical simulations. 

How to cite: Di Folco, E., Boccaletti, A., Dutrey, A., Tang, Y.-W., Guilloteau, S., and Pantin, E.: How many forming planets in the transitional disk around AB Aurigae ?, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-313, https://doi.org/10.5194/epsc2022-313, 2022.

The Habitable Zone (HZ) can be considered plainly as a measure of the potential of planetary habitability or as the parametric region about a star in which surficial water is deemed to be stable on a planet. This potential stability is a direct result of host star flux and effective radiative cooling mechanisms in accordance with the atmospheric greenhouse effect of orbiting planets. This stellar flux varies in conjunction with the temporal evolution of the host star.

Hence, we conduct the modelling of the Main Sequence (MS) and pre-MS phases of HZ evolution in order to characterise the habitability of 6 exoplanetary systems with FGK-Type host stars. In addition to this, 1 M⊙ hypothetical stars were modelled with fluctuating albedo and metallicity values to characterise the relationship of certain stellar and planetary parameters on temporal HZ evolution, to better calibrate the characterisation of exoplanet habitability in general for a diverse range of planets. This is a tool to allow us to make predictions about when or if these planets modelled are potentially habitable now, have previously been or will be in the future.

Our model simulations allow us to recommend certain exoplanets for further characterisation due to their potential current (or previous) orbit within their respective HZ, assuming they are currently considered or found to be rocky planets. These planets include Tau Ceti e, HD 40307g, Kepler 62f and e. Techniques that could be used to investigate these planets may be characterisation of their atmospheres for biosignatures using modelling of atmospheric composition to evaluate their habitability further, as situation within the HZ does not necessarily mean a planet is habitable. HZ planets, in relatively close proximity to the Earth and situated far enough from their host star to be resolved, should be probed using direct imaging to investigate surface environments, critical near-surficial conditions that may influence the stability of liquid water.

Potential future telescopes suitable for these recommendations would be the Habitable Exoplanet Imaging Mission (HabEx) and the Large Ultraviolet Optical Infrared Surveyor (LUVOIR) (Arney et al., 2018).

A major conclusion from the investigation of a 1 M⊙ hypothetical star reveals the potential for a closer inner HZ edge than formerly estimated (0.325 AU from the host star when albedo (A) = 0.9 in this work). The repercussions of this updated estimate imply that if a closely orbiting planet with a high albedo is found to orbit its host star, it may still be habitable and should not be neglected in terms of its habitability prospects. This also extends the frequency of habitable exoplanets if the inner edge of the HZ truly can exist at close proximity to the host star in question, having repercussions on exoplanet characterisation as a whole if these HZ distances can be replicated in subsequent works or verified by rocky exoplanet observations.

Furthermore, our results reinstate that a tidal-locking scenario is likely to shorten the width of the HZ significantly and draw it closer to the host star – introducing constraints for rocky bodies that may be considered habitable. This is significant when considering planets orbiting beyond the inner edge of the HZ and re-evaluation of their habitability may be necessary once atmospheric, albedo and other orbital data for exoplanetary systems can be determined.

Previous HZ publications have centred around MS habitability (Kasting et al., 1993; Kopparapu et al., 2013), yet the temporal evolution of the HZ is becoming more widely recognised as fundamental in evaluating habitability as a whole (Ramirez and Kaltenegger, 2014; Danchi and Lopez, 2013). Pre-MS evolution is a deciding factor as to whether planets are still habitable during the MS phase – planets within the pre-MS HZ are unchartered targets in the search for habitable worlds or even as tools to decipher habitable planet diversity and early water delivery mechanisms. Such results should be utilised as a first order estimation of exoplanetary habitability.

To summarise, there is still significant progress left to be made in calculating reliable HZ boundaries and to then characterise the habitability of planets orbiting within them. Nevertheless, these HZ boundaries serve as a critical basis for the assessment of the habitability of modelled exoplanetary systems. Such works are beneficial as they may result in the detection of habitable exoplanets suitable for observational follow-ups, or even to the eventuality of discovering evidence for extra-terrestrial life.

References:

• Arney, G., Batalha, N., Cowan, N., Domagal-Goldman, S., Dressing, C., Fujii, Y., Kopparapu, R., Lincowski, A., Lopez, E., Lustig-Yaeger, J. and Youngblood, A., 2018. The Importance of Multiple Observation Methods to Characterize Potentially Habitable Exoplanets: Ground-and Space-Based Synergies. arXiv preprint arXiv:1803.02926.
• Danchi, W.C. and Lopez, B., 2013. Effect of Metallicity on the Evolution of the Habitable Zone from the Pre-main Sequence to the Asymptotic Giant Branch and the Search for Life. The Astrophysical Journal, 769(1), p.27.
• Kasting, J., Whitmire, D. and Reynolds, R., 1993. Habitable Zones around Main Sequence Stars. Icarus, 101(1), pp.108-128.
• Kopparapu, R., Ramirez, R., Kasting, J., Eymet, V., Robinson, T., Mahadevan, S., Terrien, R., Domagal-Goldman, S., Meadows, V. and Deshpande, R., 2013. HABITABLE ZONES AROUND MAIN-SEQUENCE STARS: NEW ESTIMATES. The Astrophysical Journal, 765(2), p.131.
• Ramirez, R.M. and Kaltenegger, L., 2014. The habitable zones of pre-main-sequence stars. The Astrophysical Journal Letters, 797(2), p.L25.

How to cite: Hogan, J.: Characterising the Potential for Planetary Habitability: A Study of the Temporal Evolution of Exoplanet Habitable Zones, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-369, https://doi.org/10.5194/epsc2022-369, 2022.

Short-period, low-mass planets have been found to often display inflated atmospheres [1]. Here, we investigate the interior structure of such planets with a moderate water budget using a fully self-consistent planet interior model [2, 3], where water can exist in supercritical state. This has been done by increasing the working range of an existing interior model, allowing us to explore the 0.2-2.3 Earth mass range. We consider planets with water mass fractions (WMF) ranging from 0.01% to 5% and irradiation temperatures between 500 and 2000K. Moreover, we consider three possible internal compositions; a pure rocky interior, an Earth-like core mass fraction (0.325) and a Mercury-like core mass fraction (0.7).

Figure 1: Computed planetary radii Rp at the transiting depth of 20mbar as a function of planetary mass and irradiation temperature. Columns correspond to different core mass fractions (0, 0.325, 0.7, from left to right) while rows correspond to different water mass fractions (5%, 1%, 0.01%, from top to bottom). Any missing data correspond to cases where the atmosphere is hydrostatically unstable.

We find that at higher masses, the planet radius increases with the planet mass, and the radii for planets with supercritical water are greater than if water was in a condensed phase. An important mass of water can also result in a notable compression of the refractory layers (up to 0.1 Earth radius for a WMF of 5%). At lower masses, we find that the steam atmosphere inflates, and becomes gravitationally unstable when the scale height of the atmosphere exceeds ~0.1 times the planetary radius. We propose to use this H/Rp ratio as a stability criterion for steam atmospheres. 

Our data can be used to estimate the maximum WMF that can be retained by a planet given its mass, irradiation temperature and interior composition. For a given mass and temperature, a large part of the planets considered here can be stable even if constituted of 100% water. As the temperature increases or as the mass decreases, the surface gravity of a 100% water planet becomes too weak to retain the steam atmosphere. It is then possible to estimate the maximum WMF under which the atmosphere is stable.

Our results show that planets under 0.9 Earth masses should typically present unstable hydrospheres.  We also find that a sharp transition exists between a planet able to hold a 100% water atmosphere and an unstable one, as the H/Rp stability criterion exceeds 0.1. Additionally, we note that this class of planets is a viable explanation of the current Super-Puff category without invoking instrumental limitations, as the mass of water molecules induces a more inflated atmosphere than H/He planets.

References:

[1] Turbet, M., Bolmont, E., Ehrenreich, D., et al. 2020, A&A, 638, A41

[2] Aguichine, A., Mousis, O., Deleuil, M., et al. 2021, ApJ, 914, 84

[3] Vivien, H.G., Aguichine, A., Mousis, O., et al. 2022, ApJ

How to cite: Vivien, H., Aguichine, A., Mousis, O., Deleuil, M., and Marcq, E.: Constraints on the existence of low-mass planets with supercritical hydrospheres, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-418, https://doi.org/10.5194/epsc2022-418, 2022.

Convective mantle flow of terrestrial planets is governed by a temperature- and pressure-dependent rheology. This results in a stagnant-lid regime observed on most terrestrial planets. Plastic deformation can lead to breaking of the strong upper lithosphere, which resembles plate tectonics on Earth.

Most efforts to model mantle convection with self-consistent plate tectonics combine Newtonian power-law with a stress-dependent pseudo-plastic rheology.
In the uppermost mantle, where stresses are high, deformation is thought to be driven partly by dislocation creep. This is often neglected in viscoplastic consideration, which employ purely diffusion-creep-driven flow combined with a yield criterion.

In our models we employ an effective viscosity law combining both Newtonian and Non-Newtonian power laws with a pseudo-plastic model. We study the influence of rheology in combination with grain size and different yield stress parameterizations on the likelihood of the on-set of plate tectonics in a 2D-spherical annulus geometry. We compute common diagnostic values related to the characterization of a mobilized surface. With this model we aim at identifying key planetary factors for the occurrence or absence of plate tectonics. 

How to cite: Henke-Seemann, O. and Noack, L.: Critical factors for plate tectonics on rocky planets, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-585, https://doi.org/10.5194/epsc2022-585, 2022.

Benzene is the simplest organic compound with a 6-carbon aromatic ring. As such, it was used as a first order representative of aromatic compounds in planetary atmospheres. These compounds can be brought by asteroid impacts into rocky planetary atmospheres, where they can serve as precursors for further synthesis. Our experiments show that benzene vapours in nitrogen-dominated atmospheres subjected to asteroid impacts (modelled by laboratory laser shots) lead to the formation of acetylene and hydrogen cyanide. Both these products appear in many proposed mechanisms of prebiotic chemistry.

How to cite: Knížek, A. and Petera, L.: The stability of benzene in planetary atmospheres, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-830, https://doi.org/10.5194/epsc2022-830, 2022.

Exoplanets in the mass range between Earth and Saturn show a large spread in radii/densities for a given planetary mass. The most approaches to explain this spread and the distribution of planetary properties therein can be split into two groups. The first considers the planetary formation paths as the primary mechanism shaping this distribution, and the second group considers the radius spread as a consequence of the atmospheric evolution driven by the atmospheric mass loss. The majority of the latter studies, however, consider only the observed radius spread with some theoretical underlying mass distribution, as for most of the Kepler planets the mass is unknown.
In this study, we examine the mass-radius distribution of the observed planets with masses between 1 and 108 Earth masses with the aim to understand to which extent it can be explained by the evolution of planetary atmospheres driven by thermal contraction and the hydrodynamic escape, and in which regions of the parameters state the initial parameters of planets set up by specific formation processes are critical for the final (gygayears old) state.
Our modeling framework accounts simultaneously for the realistic atmospheric mass loss by interpolating within the grid of upper atmosphere models and for the thermal evolution of planets by means of the MESA code. As the atmospheric mass loss on the long timescales is strongly affected by high energy stellar radiation, we also account for the whole range of different possible stellar evolution histories as represented by the Mors code. 
We consider the grid of model planets in the mass range given above evolving at different orbital separations (corresponding to the equilibrium temperatures of ~500-1700 K) around the solar mass star. As initial parameters for our atmosphere evolution models, we adopt the predictions of the analytical approximations based on formation models (Mordasini 2020) and consider the two possible scenarios: planets formed in the inner disk (relatively small initial atmospheres) and beyond the snow line (large initial atmospheres) with consequent inward migration at the early phase of the planetary system evolution.
The whole radius spread predicted using this approach outlines well the observed distribution (including about 240 planets with mass and radius uncertainties below 45% and 15% respectively), except for a group of very close in (within ~0.1 AU) massive (~70-110 Mearth) planets with radii comparable to the Jupiter radius. The radii of these planets can not be reproduced by our models even by assuming the atmospheric mass fractions above 80% without some additional heating source. A strong correlation of the radii with equilibrium temperature (Rpl~Teq^0.7) suggests that the inflation mechanism is similar to that of the so-called "inflated Jupiters", where a range of possible explanations was suggested including the tidal interaction with the host star, vertical heat transport towards the deep atmospheric levels or the Ohmic dissipation.
The more detailed analysis shows that the low-mass end of the mass-radius distribution (below 10-15 Earth masses) is dominated by the effect of the atmospheric mass loss (and thus extremely dependent on the activity evolution history of the host star) and weakly depend on the initial parameters, and thus, on the specific formation mechanism of the exoplanets. For more massive planets, though some of them can be significantly affected by the atmospheric mass loss, the initial conditions become important and the variability in the possible stellar histories can only explain about one fourth of the whole spread. Thus, for explaining the upper boundary of the spread above ~20 Mearth one needs to consider the voluminous initial atmospheres which can be explained by the formation at the large distance from the host star. However, the activity history of the host star can be theoretically resolved using the present-day radii of the companion planets for the significant fraction of planets with masses up to ~60 Mearth.
Finally, the detailed comparison between the model predictions and the observations within different Teq intervals reveals a relatively small (~6%) but a presumably systematic group of the outliers with radii considerably smaller than the lower boundary predicted by our models for Teq<~800 K. Assuming the hydrogen dominated atmospheres surrounding rocky cores, these planets would not have more than ~1% of their mass in the envelope, while for their masses (>10 Mearth) the accretion models predict the initial atmospheric mass fraction order of 10%, and the total atmospheric mass loss throughout the evolution according to our models is insufficient to remove this much of the atmospheric material. This suggests, that the formation mechanisms and structures of these planets are considerably different from our assumption of the hydrogen-dominated atmospheres accreted onto the rocky core.

How to cite: Kubyshkina, D. and Fossati, L.: Mass-radius relation of intermediate-mass planets outlined by the hydrodynamic escape of planetary atmospheres and formation, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-1089, https://doi.org/10.5194/epsc2022-1089, 2022.

Rocky (exo)planets can be classified based on their mantle viscous state. The mantle viscosity influences the efficiency of convection and heat loss of the planet, altering the outgassing rate. Low viscous planets are hypothesized to have strong volcanic activity reshaping the surface and changing the atmosphere. This can be seen in other almost-similar rocky bodies such as Io, one of Jupiter’s Galilean moons, and would be expected of young rocky exoplanets. Whereas, the intermediate viscous planets have less vigorous resurfacing. They experience occasional complete mantle-overturn to slow-moving plate tectonics driven by mantle convection. As a result, their atmospheres vary little or smoothly across time. High viscous planets can be seen as inert, with little or no mantle convection. Moreover, hotspot volcanism might still occasionally contribute to outgassing, producing a less dominant atmosphere. Through this relationship, a planet’s atmosphere could reveal information about the evolution of a planet's interior and surface. However, we rely on primary observables to characterize (exo)planets. So, is there a correlation between a planet's orbital position and mantle viscosity? The answer to this question would aid in the characterization of rocky exoplanets, which is the focus of this work. 

To study the relationship between a planet’s mantle viscous state, interior composition, and structure. We use Perple-X to generate mineral physics properties, and Burnman to build a 1-dimensional depth profile of the planet. From this, 2-dimensional annulus compressible convection models are developed using ASPECT. And, exploring the stagnant lid, the episodic lid, and the tectonic convection regimes. We consider the anelastic liquid approximation (ALA), and the truncated anelastic liquid approximation (TALA) formulations. An isoviscous profile results in a hot mantle but can be used for first-order approximations of mantle dynamics without a crust. However, the presence of crust requires for temperature-dependent stratified viscosity profile for the deeper mantle to allow for the cooling of the mantle. The stratification structure of the mantle is determined by the temperature sensitivity of the mineral phases present in the depth profile of the mantle. The iron mass fraction of the planet, which is highly dependent on the orbital position dictates the thermal state of the given planet. Moreover, a high mass iron fraction in the mantle results in a highly viscous planet. Which cools much faster but with a higher average temperature in the earlier phases of evolution. And vice versa to a similar mantle state with less iron mass fraction in the mantle.

How to cite: Adhiambo, V., Root, B., and Desert, J.-M.: Rocky worlds: What do a planet's orbital parameters tell us about its mantle state?, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-1219, https://doi.org/10.5194/epsc2022-1219, 2022.

The growth of dust grains to dust aggregates is a very important process in the chain of events from dust to planetesimals in protoplanetary discs (PPDs). Not only the size, shape, and porosity play an important role in the collisional growth process, but also the collision speed, the type of gas coupling and the charge of the dust particles [1, 2].

The ICAPS (Interactions in Cosmic and Atmospheric Particle Systems) campaign provides an experimental approach to protoplanetary dust growth and all the above parameters under realistic PPD conditions. The first ICAPS experiment flew onboard the TEXUS-56 sounding rocket and consisted of a vacuum chamber with a cloud of micrometer-sized SiO₂ spheres embedded in a rarefied gas inside. The dust particles could be manipulated using temperature and external electric fields. During flight, the particles were observed using two overview cameras and a high-speed camera attached to a long-distance microscope. In total, three electrical scans were conducted to measure the charge distribution of the dust particles. Two of these scans (E1, E3) were applied immediately after the two dust injections, while a longer one (E2) was performed after the Brownian growth phase. Each of these scans consisted of two equal-length phases of different field polarisation. The analysis of the image recordings provided precise particle tracks and velocities as well as the mass and size of the dust aggregates [3]. From the change in velocity, when the external electric field was present, it was also possible to derive the particle charge.

Fig.1:   Charge per monomer plotted against the cumulative normalized frequency of tracked particles during the electrical scans immediately after the first dust injection (E1), after the Brownian motion phase (E2), and after the second injection (E3), respectively. The duration between E1 and E2 was 164s. In this period, the mean charge per monomer grain decreased to less than 40% of the initial value.

In Fig. 1, the electric charge per monomer grain is plotted as a cumulative normalized frequency distribution of all particles tracked during each scan. Over the duration of 164 s between E1 and E2, a reduction of the mean charge per monomer grain to less than 40% of the initial value was observed. This finding is an indication that there was a relatively large number of distributed charges immediately after the injection, which allowed rapid agglomeration due to the charge-enhanced collision cross-section. At a later stage of the experiment run, the agglomeration was likely mainly driven by Brownian motion and dipole-dipole interactions. It is planned that the evolution of grain charging during agglomeration will be explored in more detail as part of the Laplace campaign, which will use a similar setup for a variety of experiments on the ISS. 

References

[1] Blum, J., “Dust agglomeration”, Advances in Physics, vol. 55, pp. 881–947, 2006. doi:10.1080/00018730601095039.

[2] Güttler, C., Blum, J., Zsom, A., Ormel, C. W., and Dullemond, C. P., “The outcome of protoplanetary dust growth: pebbles, boulders, or planetesimals?. I. Mapping the zoo of laboratory collision experiments”, Astronomy and Astrophysics, vol. 513, 2010. doi:10.1051/0004-6361/200912852.

[3] Schubert, B., “ICAPS Sounding Rocket - Particle Growth”, 2020. doi:10.5194/epsc2020-567.

How to cite: Molinski, N., Pöppelwerth, A., Schubert, B., Schräpler, R., von Borstel, I., Houge, A., Krijit, S., Balapanov, D., Vedernikov, A., and Blum, J.: ICAPS: Charge effects in dust agglomeration experiments – Results from the TEXUS-56 sounding rocket flight, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-377, https://doi.org/10.5194/epsc2022-377, 2022.

The ICAPS experiment (Interactions in Cosmic and Atmospheric Particle Systems) was part of the Texus-56 sounding rocket flight in November of 2019. ICAPS studies the agglomeration of 1.5 µm-sized, monomeric silica grains under microgravity conditions, as would be present in the early stages of dust growth in protoplanetary disks, which our study aims at describing.

For this, a cloud of dust was injected into a vacuum chamber with ~7000 monomer grains per mm³. A thermal trap was then utilized to stabilize the dust cloud against any external disturbances during the flight. Two overview cameras and a long-distance microscope with a high-speed camera were used for the in-situ observations of the particles (see Figs. 1 and 2).

This talk focuses on the data analysis and results of ICAPS, in particular with respect to Brownian motion and aggregate growth. From the total experiment time of six minutes of almost perfect weightlessness, we extracted the masses and translational friction times of 414 dust aggregates from their translational Brownian motion. For a subset of 69 of these particles, we were also able to derive their moments of inertia and rotational friction times from their Brownian rotation. With these data, we derived a fractal dimension close to 1.8 for the ensemble of dust aggregates. We compared this unambiguous physical method for the determination of the fractal dimension with an optical approach, in which the mass is derived through the particle extinction and the moment of inertia is derived from the microscopic images.

The combination of both methods then facilitates the growth analysis, for which the overview cameras were also used. We observed an initial rapid, charge-induced growth of aggregates, which was followed by a slower growth rate, which was dominated by ballistic cluster-cluster agglomeration. As a surprise, around 100 seconds into the flight, clear indication for runaway growth (or the onset of gelation) was observed.

Fig. 1: Examples of dust aggregates from the long-distance
microscope images.

Fig. 2: Image from one of the overview cameras after 100 s of experiment time (1024 x 768 pixels, about 12 x 9 mm²).

How to cite: Schubert, B., Molinski, N., Blum, J., Glißmann, T., Pöppelwerth, A., von Borstel, I., Balapanov, D., Vedernikov, A., Houge, A., and Krijt, S.: ICAPS: Dust aggregate properties and growth derived from Brownian translation and rotation from the ballistic to the diffusive limit, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-581, https://doi.org/10.5194/epsc2022-581, 2022.

In order to form a rocky, potentially habitable planet, like Earth, the planet’s building blocks must loose volatiles. White dwarfs that have accreted planetary material provide the perfect opportunity to study the volatile content of planetary building blocks. The unique behaviour of Mn and Na depending on the conditions under which volatiles are lost means that planetary material in the atmospheres of white dwarfs can tell us how planetary building blocks lost volatiles [1]. This talk will summarise some recent results regarding observations of volatiles in the atmospheres of white dwarfs, models that describe how white dwarfs accrete volatiles and evidence from white dwarfs for volatile loss both early, in the hot, inner regions of a planet-forming disc and late, when large-scale melting is induced following impacts. 

How to cite: Brouwers, M., Bonsor, A., Harrison, J., Shorttle, O., and Malamud, U.: How do planetary bodies lose volatiles?, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-1223, https://doi.org/10.5194/epsc2022-1223, 2022.

The atmospheres of sub-Neptunes are expected to exhibit considerable chemical diversity, beyond what is anticipated for gas-giant exoplanets. Recently, in Guzman-Mesa et al 2022 we constructed self-consistent radiative transfer and equilibrium chemistry models to explore this chemical diversity. We use GJ 436 b as a case study to further study joint atmosphere-interior models. In particular, we constrain the properties of the interior and atmosphere of the planet based on the available Spitzer measurements. While it is possible to fit the emission spectrum of GJ 436 b using a high-metallicity model, we demonstrate that such an atmosphere is inconsistent with physically plausible interior structures. It remains the case that no existing study can adequately fit the 4.5-micron Spitzer secondary eclipse measurement, which is probably caused by chemical disequilibrium. In the light of the recently-launched JWST, we recommend that future analysis of emission and transmission spectra of sub-Neptune planets are carried out self-consistently using both the atmospheric and interior structure models.

How to cite: Guzmán Mesa, A.: Chemical diversity of the atmospheres and interiors of sub-Neptunes, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-25, https://doi.org/10.5194/epsc2022-25, 2022.

Ground-based high-resolution spectroscopy allows us to probe the chemical composition and atmospheric dynamics of hot jupiters through the Cross-Correlation Function method. This requires however careful data processing and development of analysis tools in order to extract such a faint exoplanetary signal from the overwhelming telluric and stellar contributions. With a high spectral resolution power of 70,000 and a large continuous spectral range between 0.9 and 2.5 microns, the near-infrared spectro-polarimeter SPIRou on the CFHT is a powerful instrument for exoplanet atmosphere characterization since its first light in 2018. I will present our analysis of SPIRou primary transit observations of some short-period exoplanets. Preliminary results regarding the detection of the metastable He triplet and molecules in the hot jupiters HD 189733b and HD 20458b, the warm neptunes GJ 3470b and Au Mic b, the mini neptune GJ 1214b, the hot neptune WASP-127b, and the warm saturn WASP-69b, will be presented.

Figure 1: Cross correlation between observed and synthetic spectra of HD189733b (expressed in S/N ratio) calculated over a grid of velocity parameters Kp (radial velocity semi-amplitude) and V₀ (additional Doppler shift of atmospheric lines at mid-transit). The correlation is maximum at the expected position in this parameter space [1]. The model spectra include water vapor as the only molecular absorber.

References :

[1] Boucher, A., Darveau-Bernier, A., Pelletier, S., Lafrenière, D., Artigau, E., et al., (2021). Characterizing Exoplanetary Atmospheres at High Resolution with SPIRou: Detection of Water on HD 189733 b. The Astronomical Journal, American Astronomical Society, 162 (6), pp.233.

How to cite: Masson, A., Vinatier, S., Bezard, B., and Team, A.: Characterizing exoplanetary atmospheres with SPIRou, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-446, https://doi.org/10.5194/epsc2022-446, 2022.

We recreate a Titan-like climate using an Earth-like global climate model (GCM) by varying a small set of planetary parameters. Understanding the range of possible climate states for Earth-like planets is important for interpreting exoplanet observations and Earth’s own climate history. We find that simply reducing the available water at the surface does not fully reproduce Titan-like conditions. This may indicate that there are many possible “in-between” states an Earth-like planet can have that span the gap between the Earth and Titan climate archetypes. We use three observationally motivated criteria to determine Titan-like conditions: 1) the peak in surface specific humidity is not at the equator, despite it having the warmest annual-mean temperatures (Ádámkovics et al. 2016); 2) the vertical profile of specific humidity in the equatorial column is nearly constant through the lower troposphere (Niemann et al. 2005); and 3) the relative humidity near the surface at the equator is significantly lower than saturation (lower than 60%; Niemann et al. 2005; Tokano et al. 2006). We first limit the available water by placing a continental land strip centered on the equator and varying its width. This mimics Titan’s dry tropics and wet poles, and could be similar to past continental arrangements in Earth’s history. Land strips alone allow some experiments to meet two Titan-like criteria, but none show the near-constant vertical profile of specific humidity. We take three of these land strip widths and vary the rotation period, starting with Earth’s rotation and moving towards Titan’s (16 Earth days). Slowing the rotation results in fewer experiments meeting any of the Titan-like criteria due to increased access to oceanic moisture from the widened Hadley Circulation. For the same three land strip widths and using Earth rotation, we vary the volatility of the condensable via a constant multiplied to the saturation vapor pressure. Titan’s condensable, methane, is more volatile under Titan’s surface conditions than water is on Earth, resulting in high specific humidities. By artificially increasing the saturation vapor pressure, we can approximate this effect without changing the properties of the condensable. Experiments with a volatility constant of 2.5 (the maximum used in this work) meet all three Titan-like criteria, demonstrating that an Earth-like planet can display Titan-like climatology by changing only a few physical parameters.

How to cite: McKinney, M. and Mitchell, J.: Dune, Waterworld, and Everything in-between: Creating a Titan-like Climate on an Earth-like Planet, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-742, https://doi.org/10.5194/epsc2022-742, 2022.

Motivation

Photochemical hazes are expected to form in the atmospheres of many hot Jupiters, especially those with equilibrium temperatures near 1,200 K (like HD 189733b) and below. Heating and cooling from photochemical hazes can strongly impact temperature structure and atmospheric circulation but has previously been neglected in 3D general circulation models (GCMs) of hot Jupiters.

Methods

We present 3D simulations of hot Jupiter HD 189733b that include radiative feedback from photochemical hazes. Hazes were simulated as radiatively active tracers with a constant particle size of 3 nm. For the nominal simulations, a complex refractive index of soot was assumed. To examine how the results depend on the choice of the refractive index, we also performed additional simulations with a refractive index of Titan-type hazes.

Effect on atmospheric circulation

The response of atmospheric circulation to heating and cooling by hazes strongly depends on the assumed haze refractive index. For simulations with soot-like hazes, the equatorial jet broadens and slows down (Fig. 1, center panel). At low pressures, the day-to-night component of the flow strengthens. Vertical velocities increase. The horizontal haze mixing ratio distribution (Fig. 2) remains relatively similar to simulations without haze radiative feedback, with particularly high haze abundances near the morning terminator (as also seen in Steinrueck et al., 2021). For simulations with Titan-type hazes, the equatorial jet instead accelerates and extends to lower pressures (Fig. 1, right panel). This results in a substantially different 3D distribution of hazes, with hazes being most abundant at the dayside, the evening terminator and the equatorial region around the planet. This means that circulation, thermal structure, and haze distribution depend strongly on the assumed haze composition and optical properties.

Fig. 1: Zonal-mean zonal velocity in a simulation without haze radiative feedback (left), with soot-like hazes (center) and with Titan-type hazes (right). Black contours highlight the regions in which the zonal-mean zonal velocity is larger than 50% and 75% of its peak value within the simulation. The haze production rates are identical for both simulations with haze radiative feedback (2.5x10^-11 kg/m²/s).

Fig. 2.: Haze mass mixing ratio at the 0.1 mbar level in a simulation with soot-like hazes (left) and with Titan-type hazes (right). The substellar point is located at the center of each panel. Both simulations shown have a haze production rate of 2.5x10^-11 kg/m²/s at the substellar point.

Effect on temperature structure and emission spectra

In all simulations with haze radiative feedback, strong thermal inversions appear at low pressures on the dayside (Fig. 3). In the soot-like case, two distinct thermal inversions form, separated by a temperature minimum below the haze production region. This additional structure is not seen in 1D simulations. It is caused by upwelling on the dayside transporting air with low haze abundance upwards, resulting in a local minimum in the haze number density below the production region. Deeper regions of the atmosphere (p>100 mbar) cool compared to simulations without hazes.

The altered temperature structure leads to changes in emission spectra (Fig. 4): The amplitude of the near-infrared water features decreases in simulations with haze radiative feedback. At wavelengths > 4 µm, the emitted flux increases. Because thermal inversions caused by photochemical hazes peak at much lower pressures than the regions probed by existing low-resolution observations, current observations of HD 189733b neither confirm nor rule out such a temperature inversion.

 Fig. 3: Dayside temperature profiles, calculated using an average weighted by the cosine of the angle of incidence

Fig. 4: Dayside emission spectra. For comparison, blackbody spectra are shown as thin gray lines.

References:

Steinrueck, M. E., A. P. Showman, P. Lavvas, T. Koskinen, X. Tan, and X. Zhang (2021). MNRAS, 504(2), pp. 2783-2799. doi:10.1093/mnras/stab1053.

How to cite: Steinrueck, M., Koskinen, T., Parmentier, V., Lavvas, P., Tan, X., and Zhang, X.: Photochemical hazes dramatically alter temperature structure and atmospheric circulation in 3D simulations of hot Jupiters, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-763, https://doi.org/10.5194/epsc2022-763, 2022.

Water-rich planets should be ubiquitous in the universe, and could represent a notable fraction of the sub-Neptune population. Among the detected exoplanets that have been characterized as sub-Neptunes, many are subject to important irradiation from their host star. As a consequence, hydrospheres of such planets are not in condensed phase, but are rather in supercritical state, with steam atmospheres on top. Such irradiated ocean planets (IOP) are good candidates to explain the distribution of masses and radii in the sub-Neptune category of exoplanets [1]. 

Here, we present the IOP model that computes the structure of water-rich planets that have high irradiation temperatures. The IOP model [2] combines two models in a self-consistent way: one for the interior structure, and one for the steam atmosphere. The interior structure model [3] contains several refractory layers (iron core and rocky mantle), and on top of them an hydrosphere with an up to date equation of state (EOS) with a validity range that extends to the plasma regime. The atmosphere model [4] connects the top of the interior model with the host star by solving equations of radiative transfer.

Our model has been applied to the GJ 9827 system as a test case and indicates Earth- and Venus-like interiors for planets b and c, respectively. Planet d could be an irradiated ocean planet with a water mass fraction of ∼20 ± 10%. We also compute mass-radius relationships for IOP and their analytical expression, which can be found in [2]. This allows one to directly retrieve a wide range of planetary compositions, without the requirement to run the model.

Due to their high irradiation temperatures, sub-Neptunes are expected to be subject to strong atmospheric escape. This supports the idea that a massive hydrosphere could be the remnant of a complete loss of an H-He envelope. The stability of hydrospheres themselves is discussed as well [5].

Figure 1. Mass-radius relationships produced by our model (green, yellow and red thick lines) [2], compared to mass-radius relationships of planets with only condensed phases and no atmosphere (black, grey and light blue thin lines). A few planets of the solar system, the GJ-9827 system and the TOI-178 system are represented as well. Shaded regions correspond to important atmospheric loss by Jeans escape (H and H2O), or hydrodynamic escape.

[1] Mousis, O., Deleuil, M., Aguichine, A., et al. 2020, ApJL, 896, L22.
[2] Aguichine, A., Mousis, O., Deleuil, M., et al. 2021, ApJ, 914, 84A.
[3] Brugger, B., Mousis, O., Deleuil, M., et al. 2017, ApJ, 850, 93.
[4] Marcq, E., Baggio, L., Lefèvre, F., et al. 2019, Icarus, 319, 491M.
[5] Vivien, H., Aguichine, A., Mousis, O., et al. 2022, accepted in ApJ.

How to cite: Aguichine, A., Mousis, O., Deleuil, M., Marcq, E., and Vivien, H.: Interior structure and possible existence of irradiated ocean planets, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-904, https://doi.org/10.5194/epsc2022-904, 2022.

The population of Earth-sized exoplanets in short orbital periods of a few Earth days around small mass stars has continuously increased over the past years [1 - 3]. A fraction of these planets has stellar irradiation levels closer to Venus than the Earth, suggesting that a Venus-like Climate is more likely on those exoplanets [4]. At the same time, their small size, combined with a close-in orbit and small radius of the host star (relatively small star-planet size ratio), makes these worlds the best targets for follow-up atmospheric studies. Furthermore, when the planet transits the host star, such as in the case of TRAPPIST-1 planets, transmission spectra become available, potentially expanding the understanding of the planets’ atmospheric composition [5, 6].

The James Webb Space Telescope will advance the atmosphere and Climate characterisation of nearby rocky exoplanets, including TRAPPIST-1 c [7, 8]. The field will expand with the support of upcoming ground-based observatories and space telescopes, such as the ESA/Ariel mission, scheduled for launch in 2029. The interpretation of the observables produced by these missions: reflection, thermal emission, and transmission spectra will need support from dedicated models and theoretical studies of exoplanetary atmospheres. In particular, 3D Global Climate Models (GCMs) are critical for interpreting the observable signal’s modulations. They provide synthetic top-of-the-atmosphere fluxes that can be disk-integrated as a function of the orbital phase. The spatial and temporal variability of these fluxes reflects the atmospheric variability of the simulated temperature and wind fields and provides insight into the large-scale circulation.

In this work, we use the Generic-GCM to simulate a possible Venus-like atmosphere on TRAPPIST-1 c, considered a benchmark for highly-irradiated rocky exoplanets orbiting late-type M-dwarf stars. The Generic-GCM has been originally developed at Laboratoire de Météorologie Dynamique for exoplanet and paleoclimate studies [9 - 11], and has been continuously improved thanks to the efforts of several teams (e.g., LAB, Bordeaux; LESIA, Paris; Observatoire astronomique de l'Université de Genève). The model uses a 3D dynamical core, common to all terrestrial planets, a planet-specific physical part, and an up-to-date generalised radiative transfer routine for variable atmospheric compositions. To simulate a Venus-like atmosphere as a possible framework for the atmospheric conditions in TRAPPIST-1 c, we took a series of assumptions: synchronous rotation, zero obliquity and eccentricity, a Venus-like, carbon dioxide dominated atmosphere with 92-bar surface atmospheric pressure, and a radiatively-active global cover of Venus-type aerosols. The overarching goal is twofold: (1) to study the large-scale atmospheric circulation of rocky exoplanets with similar stellar irradiations to Venus; and (2) to address the observational prospects by producing phase curves (reflection and emission) and transmission spectra.

The TRAPPIST-1 c first 3D modelling results indicate a strong equatorial zonal superrotation jet responsible for the advection of warm air masses from the substellar region towards the nightside hemisphere. The thermal phase curves have different amplitudes and orbital phases of peak emission depending on whether they are: (i) carbon dioxide absorption bands (e.g., 14.99-16.21 μm in Figure 1 (a)); or (ii) part of the continuum (e.g. 11.43-12.50 μm, in Figure 1 (a)). The corresponding OLR and temperature fields suggest different spectral bands sound different atmospheric levels. The carbon dioxide absorption bands sound mesospheric levels (p ~ 1 mbar), while the continuum spectral bands sound the cloud top (p ~ 37 mbar) (see Figure 1 (b-e)). We will explore and expand these initial results in the context of the thermal structure and large-scale circulation of TRAPPIST-1 c. Furthermore, we will provide transmission spectra of TRAPPIST-1 c based on the outputs from our simulations with the Generic-GCM.

Additionally, we will provide a parametric study focused on the response of the thermal structure, large-scale atmospheric circulation and predicted observables to the variation of several parameters: surface gravity and radius following mass-radius relationships, planetary rotation rate (e.g., 1:1 versus 2:1 and 3:2 spin-orbit resonances), and instellation.

Figure 1. Relation between thermal phase curves, OLR and temperature fields and remote sensing of different TRAPPIST-1 c atmospheric levels. The two emission phase curves in panel (a) planet-to-star contrast as a function of the orbital phase, for an inclination 90º are: (i) 14.99-16.21 μm (solid red line); and (ii) 11.43-12.50 μm (solid blue line). The coloured arrows identify each phase curve peak emission's orbital phase and corresponding longitude, while the two head black arrows identify the amplitude of each phase curve. The green vertical dashed lines mark the orbital phases 0 and π, corresponding to eclipse and transit, respectively. Panels (b, c) represent the time-mean OLR fields in mW/m²/cm^-1 (latitude vs. longitude) for the two selected phase curves. The red/blue cross mark the longitudinal location of the maximum peak emission over the equator. Panels (d, e) represent the time-mean temperature fields in K at two different pressure levels: p ~ 1 mbar (mesosphere) and p ~ 37 mbar (cloud top level), respectively. A white star (purple dot) identifies the substellar (antistellar) point. A solid (dashed) black line represents the equator (prime meridian), while the terminators are represented in solid blue lines. Data in all panels are time-averaged for ten orbits of TRAPPIST-1 c.

References:

[1] Gillon et al. 2017. Nature. 542.

[2] Zeichmeister et al. 2019. A&A. 627.

[3] Faria et al. A&A. 658.

[4] Kane et al. 2018. ApJ. 869.

[5] Lincowski et al. 2018. ApJ. 867

[6] Morley et al 2017. ApJ. 850

[7] JWST Proposal 2589 – Atmospheric reconnaissance of the TRAPPIST-1 planets https://www.stsci.edu/jwst/phase2-public/2589.pdf

[8] JWST Proposal 2304 – Hot Take on a Cool World: Does Trappist-1c Have an Atmosphere?

https://www.stsci.edu/jwst/phase2-public/2304.pdf

[9] Forget & Leconte, 2014. Phil. Trans R. Soc. A372.

[10] Turbet et al. 2016. A&A. 596. A112.

[11] Wordsworth et al. 2011. ApJL. 733. L48.

Acknowledgments

This work is supported by Fundação para a Ciência e a Tecnologia (FCT) through the research grants UIDB/04434/2020, UIDP/04434/2020, P-TUGA PTDC/FIS-AST/29942/2017

How to cite: Quirino, D., Gilli, G., Navarro, T., Turbet, M., Fauchez, T., Leconte, J., and Machado, P.: 3D Climate modelling of TRAPPIST-1 c with a Venus-like atmosphere and observational prospects, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-1110, https://doi.org/10.5194/epsc2022-1110, 2022.

How to cite: Chakraborty, H. and Lendl, M.: Quantifying the impact of stellar activity on transmission spectroscopy for F,G and K type host-stars, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-1181, https://doi.org/10.5194/epsc2022-1181, 2022.

MAROON-X is a red optical EPRV spectrograph on the 8m Gemini North telescope that has been in regular science operations for the last two years. Depending on the amount of time available and the interests of the organizers, I could report on the current performance of the instrument, science results, future plans, and/or lessons learned. In terms of performance, the instrument continues to deliver radial velocity precision at the sub 30 cm/s level. We have found that many field M dwarfs have activity levels well below 1 m/s on short timescales, thus opening up the possibility of detecting very small planets on orbits out to the distance of the circumstellar habitable zone with intensive observational campaigns. I will report science results from a large, homogeneous follow-up program for TESS's M dwarfs, a blind search for planets around the nearest M dwarfs, and a selection of results from community use of the instrument. We will be upgrading the instrument with a laser frequency comb to improve the long-term calibration later this year. We also have the approval to install a solar telescope feed for the instrument. A key lesson learned is the importance of continual assessment and adjustment of the calibration (i.e., don't "set it and forget it") in the EPRV regime.

How to cite: Luque, R. and the MAROON-X instrument team: An update on MAROON-X, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-90, https://doi.org/10.5194/epsc2022-90, 2022.

We will present a new instrument PLATOSpec which will be installed at E152 telescope at La Silla Observatory, Chile in 2023. PLATOSpec will be an echelle spectrograph with resolving power of 70000 capable of monitoring wavelength range from 380 to 680 nm with an expected accuracy in radial velocities around 3 m/s. PLATOSpec will have a blue sensitive chip, therefore, we will be able to provide a valuable information about the stellar activity. Main aims of PLATOSpec will be the ground based follow-up of currently TESS and later PLATO missions planetary candidates. We will be able to contribute mainly to detection and characterization of hot Jupiters and to discrimination of false positives and to determination of stellar parameters.

How to cite: Kabath, P., Vanzi, L., Hatzes, A., Guenther, E., Brahm, R., Janik, J., Minezaki, T., Skarka, M., and Karjalainen, R.: PLATOSpec a new spectrograph for the PLATO targets follow-up, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-124, https://doi.org/10.5194/epsc2022-124, 2022.

In the past half-century, a new generation of successively ever larger and more sophisticated telescopes and instruments have ushered in a golden age of remarkable results in astronomy. This road is taking us to the age of the extremely large telescopes (ELTs). Riding on this wave and contributing to it is exoplanet research. We are characterising the orbit and mass of exoplanets with Doppler measurements which, combined with the transit technique provide estimates of bulk densities and compositions. The picture is completed with upcoming space missions such as ARIEL or PLATO. To prepare the road into this new era, we propose to build the MultiArray of Combined Telescope (MARCOT). This large aperture telescope consists of multiple identical low-cost telescopes, at a fraction of the cost of building an ELT. We propose MARCOT to support science cases, such as time-domain astronomy in general and exoplanet research in particular, that are too expensive or impractical to conduct on ELTs. MARCOT will be linked through optical fibres combined by a novel Multi-Mode Photonic Lantern (MM-PL) into a MM fibre that will feed a single high-resolution echelle spectrograph, optimized for extreme-precision radial velocity measurements. We will present the status of the project focusing on the work carried out towards the conceptual design and the prototype of MARCOT, which is being built at the CAHA Observatory (Almeria, Spain), to feed the CARMENES spectrograph.

How to cite: Amado, P., Aceituno, J., Pozuelos, F., and Ortíz, J. L.: MARCOT: A new approach to a large aperture telescope with a novel multimode photonic lantern, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-312, https://doi.org/10.5194/epsc2022-312, 2022.

Technology now exists to enable large optical 
systems that are capable of resolving and measuring faint sources not 
accessible with current remote sensing instruments and detectors. The possibility 
of creating ground-based telescopes at the 50m-scale with sufficient wavefront control 
to both fully overcome the effects of the atmosphere, but with exquisite coronagraphic 
capability starting at the telescope entrance pupil, means we may solve some of the most 
fundamental cross-cutting scientific questions: like, "is there life outside of the solar system?".

The IAC is part of a consortium with the University of Hawaii and Universities in Lyon 
to develop the technologies needed for the next generation telescopes aimed at direct 
imaging of exoplanets around bright stars: the "ExoLife Finder (ELF)" telescope.
We have a detailed design for a 3.5-m diameter prototype, nicknamed Small-ELF, to
be built and installed at Teide Observatory by 2025. I will present the technological
and scientific challenges of such telescope.

How to cite: Lodieu, N., Kuhn, J., Moretto, G., Rebolo, R., Zhou, Y., Langlois, M., and Lewis, K.: Small-ELF: a propotype for the future ExoLife Finder hybrid optical telescope, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-510, https://doi.org/10.5194/epsc2022-510, 2022.

The Twinkle Space Mission is a space-based observatory that has been conceived to measure the atmospheric composition of exoplanets, stars and solar system objects. The satellite is based on a high-heritage platform and will carry a 0.45 m telescope with a visible and infrared spectrograph providing simultaneous wavelength coverage from 0.5 - 4.5 μm. The spacecraft will be launched into a Sun-synchronous low-Earth polar orbit and will operate in this highly stable thermal environment for a baseline lifetime of seven years.

Twinkle will have the capability to provide high-quality infrared spectroscopic characterisation of the atmospheres several hundred bright exoplanets, covering a wide range of planetary types. Additionally, ultra-precise photometric light curves will accurately constrain orbital parameters, including ephemerides and TTVs/TDVs present in multi-planet systems.

Twinkle is available for researchers around the globe in two ways:

1) joining its collaborative multi-year survey programmes, which will observe hundreds of exoplanets and thousands of solar system objects; and

2) accessing dedicated telescope time on the spacecraft, which they can schedule for any combination of science cases.

I will present an overview of Twinkle’s capabilities and discuss the broad range of targets the mission could observe, demonstrating the huge scientific potential of the spacecraft. Furthermore, I will highlight the work of the Science Team of the Twinkle exoplanet survey, showcasing their science interests and the studies into Twinkle’s capabilities that they have conducted since joining the mission. Finally, I will discuss ongoing, and upcoming, early career programmes related to the Twinkle mission.

How to cite: Edwards, B., Wilcock, B., Joshua, M., Tessenyi, M., Stotesbury, I., Archer, R., and Barrathwaj Raman Mohan, Y.: The Twinkle Space Mission's Extrasolar Survey, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-597, https://doi.org/10.5194/epsc2022-597, 2022.

Exoplanet observations with ground-based instruments are subject to climate conditions on Earth. Therefore, one important aspect in site selection for ground-based telescopes is the study of current climate conditions to optimise observing time. Since anthropogenic climate change is leading to a significant increase in global mean surface temperature, consequences for ground-based telescopes are likely [1], yet remain mostly unknown. The timescale needed to select the site and build a large telescope until its first light can easily take up more than a decade. In the case of the European Extremely Large Telescope, this process takes approximately 20 years. Together with a typical lifetime of 30 years for large telescopes, climate change  potentially degrades site conditions assessed during the site selection process noticeably until end of lifetime.
We present a study of eight sites around the world where ground-based telescopes are already in operation. The selected sites are namely Mauna Kea on the island of Hawaii (USA), San Pedro Mártir in Baja California in Mexico, the three Chilean sites Cerro Paranal, Cerro Tololo and La Silla, La Palma on the Canary Islands (Spain), Sutherland in South Africa and Siding Spring in Australia. From the observatories hosting these telescopes, we collect in situ measurements of temperature, specific and relative humidity, precipitable water vapour, cloud cover and astronomical seeing. We compare these in situ measurements to the fifth generation atmospheric reanalysis (ERA5) of the European Centre for Medium-Range Weather Forecasts and score the agreement. A reanalysis is a global and continuous assimilation of observations combined with weather and climate modelling and provides a connecting link between measurements and global climate models (GCMs). 
For a more holistic comparison and to study future trends, we use an ensemble of six of the highest resolution GCMs available with a horizontal grid spacing of 25-50 km. These GCMs are provided by the High-Resolution Model Intercomparison Project and developed as part of the EU Horizon 2020 PRIMAVERA project. We compare ERA5 climate output against historical GCM simulations and score their agreement. With this evaluation, we gain insights into the trustworthiness of future GCM simulations that were run up to 2050. Finally, we perform a Bayesian analysis of future trends. 
We find that ERA5 provides a good representation since it agrees well with in situ measurements over most sites. The comparison between ERA5 and PRIMAVERA shows a good agreement for temperature, specific humidity and precipitable water vapour, for which we find increasing future trends leading to a deteriorating quality of astronomical observations. For relative humidity, cloud cover and astronomical seeing, the confidence in future trends projected by the GCMs is low, due to an inadequate representation of climate conditions in comparison to ERA5. Also, the trends found for these variables are not significant.
With this study, we show that climate change should be considered an important aspect of instrumentation design for ground-based telescopes, especially for high-contrast imaging observations.

References:

[1] Cantalloube, F., Milli, J., Böhm, C. et al. The impact of climate change on astronomical observations. Nature Astronomy 4, 826–829 (2020).

How to cite: Haslebacher, C., Demory, M.-E., Demory, B.-O., Sarazin, M., and Vidale, P. L.: Climate change drives degradation of future observations with ground-based telescopes, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-791, https://doi.org/10.5194/epsc2022-791, 2022.

Ariel, the Atmospheric Remote-sensing Infrared Exoplanet Large-survey, was adopted as the fourth medium-class mission in ESA's Cosmic Vision programme to be launched in 2029. During its 4-year mission, Ariel will study what exoplanets are made of, how they formed and how they evolve, by surveying a diverse sample of about 1000 extrasolar planets, simultaneously in visible and infrared wavelengths. It is the first mission dedicated to measuring the chemical composition and thermal structures of hundreds of transiting exoplanets, enabling planetary science far beyond the boundaries of the Solar System. The payload consists of an off-axis Cassegrain telescope (primary mirror 1100 mm x 730 mm ellipse) and two separate instruments (FGS and AIRS) covering simultaneously 0.5-7.8 micron spectral range. The satellite is best placed into an L2 orbit to maximise the thermal stability and the field of regard. The payload module is passively cooled via a series of V-Groove radiators; the detectors for the AIRS are the only items that require active cooling via an active Ne JT cooler. The Ariel payload is developed by a consortium of more than 50 institutes from 16 ESA countries, which include the UK, France, Italy, Belgium, Poland, Spain, Austria, Denmark, Ireland, Portugal, Czech Republic, Hungary, the Netherlands, Sweden, Norway, Estonia, and a NASA contribution.

This presentation provides an overall summary of the science and instrument design for Ariel and presents the many activities that the Ariel team have planned to engage the science community at large and the public prior to launch. These include the Ariel Dry-Run program and citizen-science programs such as ExoClock and the Ariel Data Challenges.

How to cite: Tinetti, G., Eccleston, P., Lueftinger, T., Salvignol, J.-C., Fahmy, S., and Alves de Oliveira, C. and the Ariel team: Ariel: Enabling planetary science across light-years, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-1114, https://doi.org/10.5194/epsc2022-1114, 2022.

Tartu Observatory telescopes offer unique guaranteed access to objects in the Northern hemisphere. The observational facilities include a 1.5- m and 0.6-m classic Cassegrain reflectors, and 0.31-m remotely controllable telescope .

 The 1.5 m telescope is currently equipped with a long-slit Cassegrain spectrograph used for stellar characterisation. Historically, the objects of interest have been massive stars but we are now developing new research direction and expanding the list of targets to exoplanet- and disk-hosting stars.

We have started evaluating our capabilities to characterise host stars spectroscopically to determine their parameters and composition. In 2020, we carried out a pilot study of a TESS candidate planet host, which we found to have a rare, strong chemical peculiarity [1]. This also allowed us to prepare our tools, workflow, and end-to-end analysis. We are also contributing to the European Space Agency Ariel space mission by offering stellar activity monitoring.

The 0.6-m and 0.31-m telescopes are utilised for photometric measurements and the 0.31-m one in particular has been a workhorse for exoplanet transit monitoring. Since 2020, we have made significant preparations to develop and prove our transit observation capabilities: we have observed more than 70 transit light curves. About  half of them have been submitted to ExoClock to contribute to Ariel mission planning.

Concerning future upgrades, Tartu Observatory will have new instruments by the middle of 2023. The upgrades include procuring a medium resolution echelle spectrograph (projected bandwidth 390 nm to  750 nm, R= 25 000) and new photometer (Johnson-Cousins BVRI and SDSS filters) for the 1.5-m telescope, which will not only enhance our capabilities in both spectroscopic and photometric data retrieval of host stars. In addition, a new remote control system of the telescope will be installed and improvements on instrumentation for the 0.6-m and 0.31-m photometric telescopes will be made. 

This presentation will give an overview of our facilities, and of current and future spectroscopic and photometric capabilities.

References:

• “A rare phosphorus-rich star in an eclipsing binary from TESS”, Colin P. et al., A&A 658 A105 (2022), DOI: 10.1051/0004-6361/202142124

How to cite: Ramler, H., Kama, M., Folsom, C., Aret, A., and Eenmäe, T.: Observational Facilities and Stellar Characterization Capabilities at Tartu Observatory, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-1149, https://doi.org/10.5194/epsc2022-1149, 2022.

With the swift advance in exoplanet sciences it is now possible to characterize not only the fundamental parameters (mass and radius) of planets but also their interior structure and bulk composition. The former is known to influence on the habitability conditions of terrestrial planets, and the latter in itself is a key aspect to understand planet formation processes and the origin of their diversity.

In order to accurately assess planetary internal composition, the derivation of the chemical abundances of the host stars is of extreme importance. In particualr, stellar abundances of Fe, Si, Mg are proposed as principal constraints to reduce degeneracy in exoplanet interior structure models under assumption of identical composition of these elements in the rocky planets and their host stars.

This regularly used assumption is based on our knowledge that stars and planets form from the same primordial gas and dust cloud. It is also supported by our Solar System observations for which we know that the composition of major rock forming elements (such as Mg, Si, and Fe) in the meteorites and telluric planets (with the exception of Mercury) is similar to that of the Sun. However, direct observational evidence for the aforementioned assumption for exoplanets is absent.

By using the largest possible sample of precisely characterized low-mass planets and their host stars, we show that the composition of the planet building blocks indeed correlates with the properties of the rocky planets (see Fig. 1). We also find that on average the iron-mass fraction of planets is higher than that of the primordial values, owing to the disk-chemistry and planet formation processes. Additionally, we show that super-Earths and super-Mercuries appear to be distinct populations with differing compositions, implying differences in their formation processes. We suggest that giant impact alone is not responsible for the high-densities of super-Mercuries.

I propose an oral contribution to speak about these very recent results published in Scinece.

Fig. 1 The iron-mass fraction of the planets inferred from the planets' mass and radius as a function of the iron-mass fraction of the protoplanetary disk, estimated from the host star abundances. Super-Mercuries (in brown) and super-Earths (in blue) appear as two distinct groups.

How to cite: Adibekyan, V., Dorn, C., Sousa, S., Santos, N., Bitsch, B., Israelian, G., Mordasini, C., Barros, S., Delgado Mena, E., Demangeon, O., Faria, J., Figueira, P., Hakobyan, A., Osagh, M., Soares, B., Kunitomo, M., Takeda, Y., Jofré, E., Petrucc, R., and Martioli, E.: Diversity of terrestrial planets: a link to the chemical makeup of their host stars, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-74, https://doi.org/10.5194/epsc2022-74, 2022.

Planets smaller than Neptune are ubiquitous in the Galaxy and those around M stars constitute the bulk of warm and temperate worlds amenable for detailed atmospheric characterization. In this talk, we present a re-analysis of all the available data on small transiting planets around M dwarfs, refining their masses and radii (Luque & Pallé 2022, in press). Our precisely characterized sample reveals that this population is well described by only three discrete planet density populations, with bulk densities centered at 1.0, 0.5 and 0.24 relatively to Earth's. The first are rocky planets, the second are water worlds, and the third are puffy planets with Neptune-like densities. This density classification offers a much better insight to disentangle planet formation and evolution mechanisms, which are degenerate when using a radius-based classification. Our results are at odds with atmospheric mass loss models aiming to explain the bimodal radius distribution and suggest that the gap separates dry from water worlds rather than rocky planets with or without H/He envelopes. Formation models including type I migration explain naturally the observations independently of the accretion mechanism: rocky planets form within the snow line, water worlds form beyond and later migrate inwards. These results are to be published in Science and are currently under embargo.

How to cite: Luque, R. and Pallé, E.: On the nature of small planets orbiting low-mass stars, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-89, https://doi.org/10.5194/epsc2022-89, 2022.

With a sample of 5000 objects at hand, exoplanet demographics is beginning to grasp key aspects of the physical mechanisms lurking beneath the multifaceted hues of the observed exoplanetary architectures. Ascertaining the dependence of planetary properties on stellar mass, and whether their very formation is possible even within the short-lived protoplanetary disks surrounding massive stars, compulsorily requires a complete and unbiased census of the exoplanet population. However, most exoplanet surveys have so far focused on stars not larger than the Sun, and 90% of known exoplanets are closer to their star than the Earth is to the Sun. This strong observational bias, connected to the preference of transits and radial velocities for close-in planets and low-mass stars, has recently started being alleviated by direct imaging, a technique that is instead preferentially sensitive to young giant planets in wide orbits. Radial velocity studies have found that the occurrence of giant planets is higher around more massive stars up to about 2 M_sun; an abrupt turnover is then observed, with the occurrence eventually falling to zero at M>3 M_sun. To clarify if this trend is real, or if a wide-orbit population of giant planets is escaping detection, we have started the B-star exoplanet abundance study (BEAST), a direct-imaging study based on the high-contrast capabilities of SPHERE@VLT. BEAST is looking for exoplanets around 85 B stars belonging to the young (5-30 Myr) Scorpius-Centaurus association. While the survey is still in progress, its early results -that I will show here- are already intriguing: even binary systems such as b Centauri (Janson et al. 2021), or stars doomed to explode as supernovae such as μ² Scorpii (Squicciarini et al. 2022), can possess their planetary systems, challenging the predictions of conventional formation models.

How to cite: Squicciarini, V.: The B-star exoplanet abundance study (BEAST): at the frontier of planet formation, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-158, https://doi.org/10.5194/epsc2022-158, 2022.

A central question in exoplanetary research is the characterisation of the composition and internal structure of exoplanets. However, the observable parameters of an exoplanet are scarce and generally limited to the planet’s mass and radius and the properties of its host star. This means that it is not possible to fully constrain the internal structure parameters of an exoplanet, such as the iron core mass fraction, the presence of a water layer or the amount of gas, from these observations: The problem is intrinsically degenerate [1,2].

To overcome this difficulty, a Bayesian inference scheme is used, which is an inverse method based on Bayes’ theorem. It updates the previously assumed probability of the internal structure parameters (the prior) based on the probability of the observation given the same parameters (the likelihood), returning the posterior distribution of these parameters.

In our case, the likelihood is determined based on an internal structure model, which calculates the radius of a planet with a given mass and composition based on the planetary structure equations as described in [6]. This calculated radius and the transit depth it implies are then compared to the observed transit depth of the real planet. For the internal structure model, we use the BICEPS code as described in [4] and based on [2,3] to model the core, mantle and water layers of the planet; the atmosphere is modelled separately according to [5]. For the composition, we assume that the planetary composition matches the one of the star exactly [7].

We developed a full grid approach that has multiple advantages over the traditionally used scheme based on Markov chain Monte Carlo methods. To compensate for the higher number of sampling points that such a brute force approach requires, we trained a deep neural network to replace the internal structure model, which significantly reduces the computation time of the model. Additionally, we take into account that the measured masses and radii of the planets in the same system are correlated, since they were measured relative to the same star. This allows for an increase in computation time that is only linear when adding an additional planet. The full approach including the internal structure model is described in more detail in [8].

This method has already been used to characterise the internal structure of various exoplanets observed by the CHEOPS mission, e.g. [8] and [9] (and more submitted). As an example, Figures 1 – 4 show the internal structure of TOI-561 b, c, d and e, calculated using the planetary and stellar parameters published in [9]. Note that the corresponding figures in [9] showing the posteriors of the internal structure parameters unfortunately do not use the published stellar parameters, see [10] for more details.

Figure 1. Posterior distribution of the most important internal structure parameters of TOI-561 b using the planetary and stellar parameters published in [9]. The shown parameters are the core and water mass fractions of the solid planet, the molar fractions of Si and Mg in the mantle and Fe in the core and the gas mass of the planet in Earth masses in a logarithmic scale. The dashed lines show the 5 and 95% quantiles, while in the titles the median and the 5 and 95% quantiles are shown.

Figure 2. Same as Figure 1 but for planet TOI-561 c.

Figure 3. Same as Figure 1 but for planet TOI-561 d.

Figure 4. Same as Figure 1 but for planet TOI-561 e.

References:

[1] Rogers, L. & Seager, S. 2010, The Astrophysical Journal, 712, 974

[2] Dorn, C., Khan, A., Heng, K., et al. 2015, A&A, 577, A83

[3] Dorn, C., Venturini, J., Khan, A., et al. 2017b, A&A, 597, A37

[4] Haldemann, J., et al. (in prep.)

[5] Lopez, E. D. & Fortney, J. J. 2014, ApJ, 792, 1

[6] Kippenhahn, R., Weigert, A. & Weiss, A. 2012, Stellar Structure and Evolution, 2nd edn., Astronomy and Astrophysics Library (Berlin Heidelberg: SpringerVerlag)

[7] Thiabaud, A., Marboeuf, U., Alibert, Y., Leya, I., & Mezger, K. 2015, A&A, 580, A30

[8] Leleu, A., Alibert, Y., Hara, N.C., et al. 2021, A&A, 649, A26

[9] Lacedelli, G., Wilson, T.G., Malavolta, L., et al. 2022, MNRAS, 511, 4551–4571

[10] Piotto, G., et al. (in prep.)

How to cite: Egger, J. A., Alibert, Y., Haldemann, J., and Venturini, J.: A Neural Network Based Approach to Modelling the Internal Structure of Transiting Exoplanets and Its Application to Planets Observed by the CHEOPS Mission, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-320, https://doi.org/10.5194/epsc2022-320, 2022.

Warm Jupiters provide a unique opportunity to better understand the formation and evolution of planetary systems. Their atmospheric properties remain largely unaltered by the impact of the host star, and their orbital arrangement reflects a different, and less extreme, migrational history compared to close-in objects. Warm Jupiters are known to cover a wide range of eccentricities but it is unclear which are the dominant formation pathways to explain this observation. Increasing the sample of long-period exoplanets with known radii is thus crucial. In this talk, I report the results of a survey set out to find transiting giants with orbital periods between 20 and 200 days. We selected 50 stars which show a single transit in one TESS sector (27 day baseline) and followed them with ground-based photometric and radial velocity facilities (e.g. NGTS, HARPS). After one year of observations, we report the detection and characterization of ten new transiting warm Jupiters, increasing by 50% the number of known warm Jupiters with precise masses and radii. We infer the metal enrichment of the newly discovered warm Jupiters and explore their influence on the mass-metallicity correlation of giant planets. The growing sample of warm Jupiters allows us to interpret these systems in terms of planet formation models. Finally, these targets orbit bright stars and thus are ideal for follow-up studies of the planetary atmosphere and the system' spin-orbit alignment. This work is a stepping stone for PLATO, as identification and follow up of single transit events will be key in order to detect transiting Earth-sized planets in the habitable zone of Sun-like stars.

How to cite: Ulmer-Moll, S., Lendl, M., Gill, S., Villanueva, S., Hobson, M., Mordasini, C., and Bouchy, F.: From TESS single transits to well-characterized warm Jupiters, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-403, https://doi.org/10.5194/epsc2022-403, 2022.

Detecting exoplanets via the transit method is inherently biased towards short-period planets. Due to the nature of its observing strategy, the Transiting Exoplanet Survey Satellite (TESS) is particularly susceptible to this detection bias; only 12% of planets confirmed by TESS have orbital periods longer than 20 days. It’s crucial that we expand this sample of long-period planets to gain a more complete view of the exoplanet population. One way to do this is using duotransits - planet candidates with two observed transits separated by a large gap, typically two years. The true period of the duotransit is unknown, instead they have a discrete set of possible period aliases. We use these aliases to perform targeted follow-up of the duotransit with the CHaracterising ExOPlanets Satellite (CHEOPS), to recover the true period and ultimately confirm the planet. This allows us to find longer-period planets than are typically found by the TESS mission alone. To select the optimal targets for our CHEOPS follow-up we have developed a specialised pipeline that searches for duotransits in the TESS data. We will present this duotransit pipeline and the results from our CHEOPS follow-up program so far. We have discovered 10 long-period exoplanets, including two planets in the TOI-2076 system, all of which have P > 21 days, R_P < 5 R_Earth and Gaia magnitude < 12. Previously there were only 8 exoplanets discovered by TESS in this exciting parameter space, so our work has more than doubled the sample. These small, long-period transiting exoplanets are amenable to radial velocity follow-up and future atmospheric characterisation with the recently launched James Webb Space Telescope (JWST).

How to cite: Tuson, A. and the CHEOPS Consortium: A Search for Long-Period Transiting Exoplanets with TESS and CHEOPS, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-499, https://doi.org/10.5194/epsc2022-499, 2022.

In this talk I will present our project that is dedicated to the search for transiting planets around hot subdwarfs (sdOB). These peculiar bodies are evolved stars that lost most of their envelope at the tip of the Red-Giant-Branch (RGB). They are small, hot and short-lived stars which have the interesting particularity to have no confirmed planets around them. In this project we perform a wide analysis of all the sdOB observed by the missions Kepler, K2, TESS and CHEOPS in order to, firstly, find transiting planets and compute their occurrence rates and secondly, bring observational constraints for the survival of close-in planets while their host star goes through the RGB. With our current technological means it is often impossible to reach Earth-sized bodies around post-RGB stars, but thanks to the small size of sdOB stars, we are able to do it here. Moreover, the short lifetime of sdOB would most likely not allow for planetary migration or the formation of second-generation planets, which means that short-period planets around them would correspond to planets that were engulfed during the RGB phase. This make them pristine candidates to understand the fate of close-orbiting exoplanets after the RGB phase of their host. In this talk I will present the method we set to analyse the data, from the initial search run to the confirmation steps of interesting signals. I will put an emphasis on the analysis of the 792 sdOB observed during the cycle 1 of the mission TESS as this part is now finished and is the topic of a submitted paper (Thuillier et al. 2022).

How to cite: Thuillier, A., Van Grootel, V., Pozuelos, F., Devora-Pajares, M., Siess, L., and Charpinet, S.: A search for transiting planets around hot subdwarfs - Results from TESS Cycle I, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-514, https://doi.org/10.5194/epsc2022-514, 2022.

In the age of JWST, temperate terrestrial exoplanets transiting nearby late-type M dwarfs provide unique opportunities for characterizing their atmospheres, as well as searching for biosignature gases. In this context, the benchmark TRAPPIST-1 planetary system has garnered the interest of a broad scientific community.

The SPECULOOS (Search for habitable Planets EClipsing ULtra-cOOl Stars) project, an exoplanet transit survey targeting a volume-limited (40 pc) sample of about 1700 late-type (M6 and later) dwarfs using a network of 1m-class robotic telescopes, began its scientific operations three years ago. In this talk, I will present an update on the current status of the survey and an overview of recent results.

In particular, I will describe how an efficient synergy with the TESS mission and other ground-based facilities led to the exciting new discovery of two temperate super-Earths transiting a nearby M6 dwarf, with the outer one orbiting in the habitable zone. In terms of potential for atmospheric characterization, we estimate that this planet is the second-most favorable habitable-zone terrestrial planet found so far after the TRAPPIST-1 planets. The discovery of this remarkable system offers another rare opportunity to study temperate terrestrial planets around our smallest and coolest neighbours.

How to cite: Delrez, L. and the SPECULOOS team: An update on the SPECULOOS project and new results, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-529, https://doi.org/10.5194/epsc2022-529, 2022.

The successful Kepler and TESS missions have discovered thousands of exoplanets and let the community focus on the characterisation of these bodies. One area of research utilises ultra-high-precision photometric and spectroscopic follow-up observations in order to accurately constrain the bulk densities of terrestrial exoplanets. Combining these observables with Bayesian internal structure modelling that uses geological equations of state, we can start to learn about the compositions of planets around main-sequence stars for the first time. Importantly, by studying multi-planet systems we can conduct comparative planetology that can reveal important aspects that challenge our knowledge of planet formation and evolution via the contrastment of the observational and modelling results of a planet against its neighbours.

In this talk, I will present observational studies characterising multi-planet systems initially discovered with TESS and followed-up with ultra-high precision photometry from the recently launched CHEOPS satellite and ground-based RV instruments, such as HARPS and HARPS-N. Additionally, I will discuss our Bayesian internal structure and atmospheric escape analyses, and present the results of utilising such models on several key, multi-planet systems observed with CHEOPS, such as TOI-1064 and TOI-561, that are expected to become cornerstones of exoplanet characterisation due to the questions they raise about planet formation, the system multiplicity, or the amenability to atmospheric observations. Important knowledge about these new systems was uncovered via the refined radii, masses, and densities, a combination of precise observations using a new generation of instruments across different techniques, and cutting-edge planetary internal structure modelling. Therefore, utilising these resources we are at the beginning of a new era in characterising terrestrial bodies outside of our Solar System that will be strengthened with JWST.

How to cite: Wilson, T.: Characterising the internal structures of small exoplanets with CHEOPS, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-944, https://doi.org/10.5194/epsc2022-944, 2022.

In this porter, we present SHERLOCK, an end-to-end pipeline that allows the users to explore the data from space-based missions such as TESS and Kepler/K2 to search for planetary candidates. It can be used to recover alerted candidates by the automatic pipelines such as the Science Processing Operations Center (SPOC) and the Quick Look Pipeline (QLP), the so-called Kepler objects of interest (KOIs) and TESS objects of interest (TOIs), and to search for candidates that remain unnoticed due to detection thresholds, lack of data exploration or poor photometric quality. To this end, SHERLOCK has six different modules to (1) acquire and prepare the light curves from their repositories, (2) search for planetary candidates, (3) vet the interesting signals, (4) perform a statistical validation, (5) model the signals to refine their ephemerides, and (6) compute the observational windows from ground-based observatories to trigger a follow-up campaign. To execute all these modules, the user only needs to fill in an initial yaml file with some basic information, such as the star ID, the cadence to be used, etc., and use sequentially a few lines of code to pass from one step to the next. Alternatively, the user may provide SHERLOCK with the light curve in a csv file, where the time, the normalized flux, and the flux error need to be given in columns comma-separated format. SHERLOCK is being used in the SPECULOOS project, which is searching for transiting Earth-sized planet orbiting ultra-cool stars in the habitable zone. These planets provide the best opportunities for future atmospheric characterization of temperate small rocky worlds. In addition, SHERLOCK is used in the FATE project, a survey that aims to find transiting planets orbiting hot subdwarfs. Thanks to their small sizes, these stars represent excellent opportunities for addressing the question of the evolution of planetary systems once their host stars left the main sequence and passed through the red giant branch phase. SHERLOCK is an open-source friendly-user package available at https://github.com/franpoz/SHERLOCK

How to cite: Pozuelos, F. J., Dévora-Pajares, M., Thuillier, A., Van Grootel, V., and Suarez Yanes, J. C.: SHERLOCK: A python pipeline to explore space-based observations in the search for planets, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-970, https://doi.org/10.5194/epsc2022-970, 2022.

Planet-star interactions are considered to have a Janus-faced character. Most of the known forms belong to star-to-planet interactions, for which well-known examples are the stellar irradiation, rotation and stellar activity affecting the planet. We can only rarely see planet-to-star scenarios, mostly because of the smaller planets can less affect the stellar physics. In this talk, we review three examples for such scenarios, including commensurabilities between the stellar spin and the planetary orbit, excitation of stellar activity, and stellar oscillations suffering planetary perturbations. The observational basis of our examples, Kepler-13A, AU Mic and WASP-33 also cover the three major exoplanet missions: Kepler, CHEOPS and TESS, nicely showing how the space-based exoplanet photometry started revealing the (almost) hidden face of Janus.

How to cite: Szabó, G.: Examples for planet-to-star interactions, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-1059, https://doi.org/10.5194/epsc2022-1059, 2022.

The orbits and dynamics of exoplanet systems can unveil their tales of formation, migration, star-planet interactions, and atmospheric properties. Kepler, TESS, and soon PLATO deliver an unprecedented wealth of new photometric data on this matter, while ground-based follow-up and radial velocity instruments add valuable insights. Here, I will present how we can unite and untangle all this data on exoplanets' orbits and dynamics using allesfitter. This open-source python software enables flexible and robust inference of stars and exoplanets from photometric and radial velocity data. Allesfitter offers a rich selection of orbital and transit/eclipse models, accommodating multiple exoplanets, multi-star systems, transit-timing variations, and phase curves. It can also help mitigate and/or study stellar variability, starspots, and stellar flares. I will highlight some of allesfitter's science output on examples of exoplanet dynamics (e.g., TOI-270 and TOI-216) and orbital phase curves (e.g., WASP-18 and WASP-121). With TESS' extended mission and PLATO on the horizon, a wealth of new data soon face us, allowing TTV and phase curve studies of dozens of such systems over many years.

How to cite: Günther, M. N.: Studying exoplanet orbits & dynamics with allesfitter, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-1180, https://doi.org/10.5194/epsc2022-1180, 2022.

The composition of several exoplanet atmospheres has been largely debated with contrasting results in the literature. Low- and high-resolution spectroscopy offer complementary views, although sometimes appear to be in sparkling contrast. We present a new approach to simultaneously model low- and high-resolution observation and apply this method to resolve known controversies in the literature. We show that the synergy between different techniques of observations is significantly more informative than the separate analyses. We recommend the joint analysis of low- and high-resolution exoplanet spectra to fully exploit the potential of upcoming space missions, such as JWST, Twinkle and Ariel.

How to cite: Morello, G., Pallé, E., Orell-Miquel, J., Masseron, T., and Esparza-Borges, E.: Synergies between low- and high-resolution spectroscopy of exoplanet atmospheres, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-1233, https://doi.org/10.5194/epsc2022-1233, 2022.

Introduction

One of the main topics of astrobiology research is the study of life’s limits in stressful environments. The study of organisms in extreme environments might give an indication about their potential adaptive plasticity, in the view of a climate change perspective, the terrestrial geological past and future scenarios, as well as extra-terrestrial habitats such as Mars’ surface. Lichens - with their excellent adaptive abilities - represents an extremely interesting case study. Several astrobiological studies involving lichens - that are symbiotic association between a fungus and an alga and/or acyanobacterium - proved the ability of these organisms to resist and thrive in extreme environments such as space and Mars’ surface simulated conditions [1, 2]. We have already tested the lichen species Xanthoria parietina (L.) Th. Fr. in simulated space conditions, that was able to survive and to reactivate after exposure [3]. X. parietina is a cosmopolitan foliose lichen that grows on barks and rocks [4]. This species shows high tolerance to air pollutants, heavy metals, and resistance to UV-radiation thanks to the shielding properties of the secondary metabolite parietin [5, 6]. Here we present a new study on the survival of X. parietina under simulated Mars conditions performed at the Mars Simulation Facility of the DLR Institute of Planetary Research in Berlin (Fig.1).

Figure 1 - Mars Simulation Facility at DLR with the opened experiment chamber.

Methods

The aim of the study was to assess the survivability of Xanthoria parietina under simulated Mars conditions for 30 days [7, 8]. Inside the Mars simulation chamber, eight samples (Fig.2) were exposed to the simulated atmospheric conditions of Mars of which four were fully UV-irradiated with day-night cycles (FM, Full-Mars) and the other four kept in darkness (DM, Dark-Mars). A three-gas mixture of 95% CO₂, 4% N₂ and 1% O₂ was used as best approximation of Mars-like atmospheric conditions, with a constant pressure of 600Pa. Temperature and humidity were subjected to day-night cycles, reaching during daytime 15°C and 0% RH, and during night -55°C and 100% RH (Fig.3) according to Martian thermophysical conditions at mid-latitudes. UV-radiation for FM samples was simulated using a Xenon UV-lamp (spectral range 200 nm – 2200 nm) that was automatically turned on for 16 h (day) and turned off for 8 h (night) daily. The total average radiation dose for FM was 2452.32 J/cm² and the average instantaneous irradiance on the sample spots was 14,2 W/m² [9]. Four other samples (Fig.2) were kept in control conditions during the experiment, at the constant temperature of 25°C, daily wetted and 12h dark and 12h light (ca. 50 μmol m^-2 s^-1 PAR photons). Several analyses were carried out to study all the samples before, during and after the exposure to the extreme Mars conditions. In detail, this experiment was performed aiming:

• to monitor the lichen vitality through chlorophyll a fluorescence (F_V/F_M) as photosynthetic efficiency parameter, carrying out in situ and after treatment analyses,
• to evaluate the oxidative stress due to the extreme conditions, highlighting eventual changes in the lichen carotenoids’ Raman signatures,
• to verify eventual modifications in the infrared features (peak shifting) in the lichen FTIR reflectance spectrum possibly related to UV-photodegradation effects,
• to highlight possible variations in the lichen ultrastructure through TEM analysis.

Figure 2 - Xanthoria parietina samples ready for the experiment. First row (from above): full Mars samples, second row: dark Mars samples, third row: control samples.

Figure 3 - Detail of the day-night cycles of the simulated Mars conditions (temperature, red thick line; humidity, blue thin line) and fluorescence variation values for both the treatments (FM and DM).

Results

The results showed significant differences between FM and DM photosynthetic efficiency parameter during exposure to Mars environment, exhibiting F_V/F_M values correlated with temperature and humidity day-night cycles (Fig.3). The F_V/F_M recovery values showed significant differences between the treatments too, highlighting that FM conditions caused stronger effects on fluorescence values. Additional analyses show possible changes in the Raman and FTIR spectra of the irradiated samples with several features involved. Overall, Xanthoria parietina was able to survive to FM conditions, and for this reason it may be considered a candidate for long exposure in space and evaluations on the photodegradability of parietin in extreme conditions.

Reference

[1] Onofri, S., de la Torre, R., de Vera, J. P., Ott, S., Zucconi, L., Selbmann, L., Scalzi, G., Venkateswaran, K. J., Rabbow, E., Sánchez Iñigo, F. J., and Horneck, G. (2012). Survival of rock-colonizing organisms after 1.5 years in outer space. Astrobiology, 12(5), 508-516.

[2] De Vera, J. P., Möhlmann, D., Butina, F., Lorek, A., Wernecke, R., and Ott, S. (2010). Survival potential and photosynthetic activity of lichens under Mars-like conditions: a laboratory study. Astrobiology, 10(2), 215-227.

[3] Lorenz, C., Bianchi, E., Benesperi, R., Loppi, S., Papini, A., Poggiali, G., & Brucato, J. R. (2022). Survival of Xanthoria parietina in simulated space conditions: vitality assessment and spectroscopic analysis. International Journal of Astrobiology, 1-17.

[4] Nimis P.L., 2016. ITALIC - The Information System on Italian Lichens. Version 5.0. University of Trieste, Dept. of Biology, (http://dryades.units.it/italic), accessed on 2022, 05, 09. for all data contained in the taxon pages, including notes, descriptions, and ecological indicator values. 

[5] Silberstein, L., Siegel, B., Siegel, S., Mukhtar, A., and Galun, M. (1996). Comparative Studies on Xanthoria parietina, a Pollution Resistant Lichen, and Ramalina duriaei, a Sensitive Species. I. Effects of Air Pollution on Physiological Processes. The Lichenologist, 28:355-365.

[6] Solhaug, K. A., and Gauslaa, Y. (1996). Parietin, a photoprotective secondary product of the lichen Xanthoria parietina. Oecologia, 108:412-418.

[7] Lorek, A., and Koncz, A. (2013). Simulation and measurement of extraterrestrial conditions for experiments on habitability with respect to Mars. In Habitability of Other Planets and Satellites (pp. 145-162). Springer, Dordrecht.

[8] De Vera, J. P., Schulze-Makuch, D., Khan, A., Lorek, A., Koncz, A., Möhlmann, D., and Spohn, T. (2014). Adaptation of an Antarctic lichen to Martian niche conditions can occur within 34 days. Planetary and Space Science, 98, 182-190.

[9] Cockell, C. S., Catling, D. C., Davis, W. L., Snook, K., Kepner, R. L., Lee, P., and McKay, C. P. (2000). The ultraviolet environment of Mars: biological implications past, present, and future. Icarus, 146(2), 343-359.

How to cite: Lorenz, C., Bianchi, E., Poggiali, G., Alemanno, G., Benesperi, R., Brucato, J. R., Garland, S., Helbert, J., Lorek, A., Maturilli, A., Papini, A., de Vera, J.-P., and Baqué, M.: Survivability of Xanthoria parietina in simulated Mars conditions for 30 days, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-189, https://doi.org/10.5194/epsc2022-189, 2022.

Some organisms have shown to be able to naturally survive environments which we consider extreme, including the Low Earth Orbit, or even Outer Space. These microorganisms have natural mechanisms to repair severe DNA damage, such as the caused by ionizing and non-ionizing radiation or extreme temperatures and pressures. Some examples are Deinococcus radiodurans, which proved to be capable of surviving in the Exposure Facility of the International Space Station (ISS) for up to three years, and tardigrade species, such as Ramazzottius varieornatus, which are some of the most resilient known organisms. In this study, performed at the Barcelona Biomedical Research Park in collaboration with Hospital del Mar, survival under simulated Low Earth Orbit environmental conditions was tested in engineered and wild-type Escherichia coli strains. Ionizing radiation resistance was enhanced by transforming the Dsup gene from R. varieornatus and two genes from D. radiodurans involved in DNA damage repair, RecA and uvrD. This enhancement, together with a directed evolution process, resulted in a significant increase in the surviving fraction of the E. coli strain protected with the Dsup gene after a high dose, up to 3000 Gy, of ionizing radiation exposure in the form of a continuous spectrum of X-ray photons. Additionally, the survival to wide ranges of temperatures and low pressures was tested for the same strains, revealing a lack of relevance of cell aggregation for survival under the mentioned conditions in contrast with the case of D. radiodurans. However, survival rates showed no enhancement for any of the new E. coli strains. In a new collaboration with the Subterranean Laboratory of Canfranc, both the absence of radiation and extreme levels of radiation will be further studied. Additionally, an extreme environments analogue for several environmental conditions will be built, allowing for more specific testing on a controlled environment. This research represents a first step in the creation of new bacterial strains engineered to survive severe conditions and adapting existing species for their survival in remote environments, like extra-terrestrial habitats. These species could pave the road for future human expeditions, helping develop environments hospitable to life. In addition, studying the efficacy and the functioning of the genetic mechanisms used in this study could be beneficial for fields such as ecological restoration and medical and life sciences engineering, addressing treatments and/or diseases caused or related to radiation and DNA damage. Space is believed to be the last frontier, but the truth is, we are still a frontier to ourselves.

How to cite: Puig, J., Knödlseder, N., Quera, J., Algara, M., and Güell, M.: DNA Damage Protection for Enhanced Bacterial Survival Under Simulated Low Earth Orbit Environmental Conditions in Escherichia coli, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-378, https://doi.org/10.5194/epsc2022-378, 2022.

Martian regolithic soil is considered an inhospitable environment to life as we know it with low availability of nutrients and the presence of powerful oxidants, namely perchlorate salts. Extreme microorganisms such as cyanobacteria of the genus Chroococcidiopsis dominate rock-dwelling communities in extreme deserts resembling the actual Martian environment. The strain Chroococcidiopsis 029, extremely tolerant to desiccation, ionizing, and UV radiation, can thrive in Mars-like conditions in a dried state. In the present work, we investigated the response of Chroococcidiopsis 029 when grown for a 3-week period using Martian regolith simulant containing 2.4 mM perchlorate anions. The growth either in the planktonic cells or biofilm life style was monitored following the in chlorophyll a content. The cellular and molecular responses to 2.4 mM perchlorate anions was studied following cell viability according to: i) PCR-PMA assay, ii) changes in gene expression of three SOD-coding genes (soda 2.1, soda.2, and sodC), and iii) production of intracellular ROS as revealed by CLSM. Results suggested that perchlorate did not compromise cell viability and that a significant over-expression of three SOD isoforms occurred after the one-week exposure with a greater expression of the membrane-bound MnSOD (sodA 2.1) in comparison to the cytoplasmic isoforms MnSOD (sodA 2.2) and Cu/ZnSOD (sodC). The accumulation of ROS within the cells was observed after 1-day exposure to perchlorate. Future investigations on the effect of Mars-like conditions in hydrated biofilms with 2.4 mM ClO4- and Martian regolith simulant will be carried out supported by the Europlanet scholarship 2024. These results are relevant for the habitability of Mars and the development of In-situ Resource Utilization.

How to cite: Gallego Fernandez, B., Mosca, C., Fagliarone, C., and Billi, D.: Responses of a desert cyanobacterium to prolonged exposure to perchlorate: implications for the habitability of Mars and In-Situ Resource Utilization, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-537, https://doi.org/10.5194/epsc2022-537, 2022.

Introduction. The harsh oxidative and radiative conditions of the Martian environment influence the fate of organic molecules present on its surface. Formation of radical species was suggested to transform organic macromolecules into carboxylic acid through Fenton chemistry (1, 2) or irradiation semiconductor surfaces (3). Aromatic carboxylic acids such as phthalic acid or benzoic acid are thought to be abundant on the Martian surface as they are in stable intermediate oxidation states and can be formed from the oxidation of Polycyclic Aromatic Hydrocarbons (PAHs) (1, 4) or alkylbenzene compounds (4) coming from endogenous or exogenous sources. Because benzene carboxylates are metastable, they should not be entirely oxidized into volatile molecules such as CO₂ or O₂, but instead, ionized by solar radiation to form organic salts (2, 4, 5). Benner et al. (2000) suggested that the low volatility of these salts could compromise their in situ detection through thermal extraction analyses as performed by analytic chemistry laboratories onboard Martian surface probes, such as the Sample Analyzer at Mars (SAM) experiment onboard Curiosity rover or the Mars Organic Molecular Analyzer (MOMA) instrument of the Rosalind Franklin Exomars rover (4-6). To determine the possibility to identify these molecules through direct or indirect detection on Mars, we examined laboratory results from SAM and MOMA-like Gas Chromatography-Mass Spectrometry (GC-MS) analyses of two acid/salt couples (phthalic acid/calcium phthalate and benzoic acid/calcium benzoate). We analyzed the difference in behavior and signatures of both molecular forms when using pyrolysis and wet chemistry experiments used in SAM and MOMA, and the relevance of these results in the search of organic molecules on Mars.

Method. Synthetic samples were made by mixing the carboxylic acid molecules or their organic salts standards at 1wt.% in fused silica, to simulate a relatively inert mineral matrix. The samples were pyrolyzed in SAM-like conditions with a ramp of 35°C.min^-1 and in MOMA-like conditions in flash pyrolysis at 500°C and 800°C.  The volatiles released from each sample were analyzed by Evolved Gas Analysis (EGA) and Gas Chromatography-Mass Spectrometry (GC-MS). We also performed derivatization experiments to help detect refractory organic compounds, with N,N-methyl-tert-butyl-dimethylsilyltrifluoroacetamide (MTBSTFA), used for wet chemistry experiments in SAM, and N,N-Dimethylformamide dimethyl acetal (DMF-DMA), to be used in the MOMA experiment of the ExoMars mission.

Organic acid/salt behavior under pyrolysis conditions. As predicted by Benner et al. (4), when analyzed through pyrolysis-GC-MS, the organic salts species did not produce the organic parent molecule (phthalic acid or benzoic acid (Fig. 1 (a)). However, we have identified two by-products characteristic of the degradation of the organic salts, diphenylmethane (Fig. 1 (b)) and triphenylmethane (Fig.1 (b)) which were absent of the chromatograms of the acid species. These results show that for both carboxylic acid couples studied, the acid and the salt don’t follow the same degradation pathway resulting in differences in the species detected as well as major differences in the abundance of products observed in the chromatograms. This means that if carboxylic acids are present on Mars in their saline form linked to calcium cations, we would not be able to identify it through the detection of its acid form with the SAM nor MOMA pyrolysis set-ups, but rather through the detection of characteristic by-products that would serve as indirect clues for identification.

Figure 1. Chromatograms obtained under the same analytical conditions as the pyrolysis in SAM. (a) benzoic acid mixed at 1 wt. % in fused silica and (b) calcium benzoate mixed at 1 wt. % in fused silica.

Organic acid/salt derivatized with MTBSTFA and DMFDMA.

Figure 2. Bar chart representing the abundance of derivatized benzoic acid obtained with calcium benzoate and benzoic acid. The derivatization reagent used was DMFDMA (a) and MTBSTFA (b).

When derivatized with DMFDMA or MTBSTFA, both the acid and the organic salt produced the derivatized product of the carboxylic acid. Both the phthalic acid and benzoic acids have a higher derivatization yield than their salt counterpart with both derivatization reagents. This is likely due to a better availability of the hydrogen on the carboxylic acid function. Moreover, we obtained a higher yield of both the acid and the salt with MTBSTFA than with DMF-DMA, with the loss of detection of calcium phthalate derivative with the latter. In conclusion, if present in the Martian soil, aromatic organic salts could be directly detected through wet chemistry experiments, showing the complementarity of this technique with pyrolysis.

References. (1) Oró et al. (1979) Life Sciences and Space Research, 77-86. (2) Donald et al. (2013) Science. (3) Fox et al. (2019) Journal of Geophysical Research: Planets 124, 3257-3266. (4) Benner et al. (2000) Proceedings of the National Academy of Sciences 97, 2425-2430. (5) Lasne et al. (2016) Astrobiology 16, 977-996. (6) Hakkinen et al. (2014) Environ Sci Technol 48, 13718-13726.

How to cite: Mcintosh, O., Szopa, C., Freissinet, C., Buch, A., and Boulesteix, D.: Analysis of aromatic organic salts with gas chromatography-mass spectrometry and implications for their detection at Mars surface with in situ experiments , Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-590, https://doi.org/10.5194/epsc2022-590, 2022.

Energy from active serpentinization processes potentially fuelled the origin of life on Earth, thus, if serpentinite-impacted sites facilitate microbial habitability, it is important to understand the source and retention of biological signatures in serpentine rocks. Investigating biological signatures in terrestrial analogues of serpentinite-impacted environments is also essential for interpreting molecular signature preservation on extra-terrestrial bodies.

To expand knowledge on the types of biological signatures directly derived from living microorganisms (intact polar lipids, IPLs), and both living and dead microorganisms (core lipids), mass spectrometry analysis was performed on Chimaera serpentinite rocks from Antalya Province, Turkey. Brucite rocks were dominated by IPLs from fungal, eukaryotic origin but in contrast, travertine samples had IPL profiles consistent with a mixed fungal, archaeal and bacterial community. The abundance and diversity of archaeal IPLs was significantly higher in the travertine compared to the brucite, and the abundance of archaeal IPLs inside the travertine rock was highest. Archaeal specific core lipids identified inside the brucite rock were not observed as IPL counterparts, suggesting the presence of a non-viable or fossil archaeal community. Comparing IPL profiles with core lipids can discriminate between living microbial communities, necromass, and fossils to combine as a promising molecular tool for identification and interpretation of bio-signatures in serpentinite-impacted sites. Continuing survey of serpentinization samples on Earth can act as analogue environments and provide valuable insight into microbial habitability on Mars and other planetary objects.

How to cite: Zetterlind, A., Rattray, J. E., Smittenberg, R. H., Potiszil, C., ten Kate, I. L., and Neubeck, A.: Lipidomics Based Microbial Ecology Snapshot of Ophiolitic Rocks, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-952, https://doi.org/10.5194/epsc2022-952, 2022.