EXO7

How to cite: Edwards, B., Tessenyi, M., Stotesbury, I., Archer, R., Joshua, M., and Wilcock, B.: Twinkle: Update on the international, collaborative exoplanet survey, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-572, https://doi.org/10.5194/epsc2021-572, 2021.

The James Webb Space Telescope (JWST), currently scheduled to launch in 2021, will dramatically advance our understanding of exoplanetary systems with its ability to directly image and characterise planetary-mass companions at wide separations through coronagraphy. Using state-of-the-art simulations of JWST performance, in combination with the latest evolutionary models, we present the most sophisticated simulated mass sensitivity limits of JWST coronagraphy to date. In particular, we focus our efforts towards observations of members within the nearby young moving groups 𝛽 Pictoris and TW Hya. These limits indicate that whilst JWST will provide little improvement towards imaging exoplanets at short separations, at wide separations the increase in sensitivity is dramatic. We predict JWST will be capable of imaging sub-Jupiter mass objects beyond ∼30 au, sub-Saturn mass objects beyond ∼50 au, and that beyond ∼100 au, JWST will be capable of directly imaging companions as small as 0.1 𝑀_J − at least an order of magnitude improvement over the leading ground-based instruments. Probing this unexplored parameter space will be of immediate value to modelling efforts focused on planetary formation and population synthesis. JWST will also serve as an excellent complement to ground based observatories through its unique ability to characterise previously detected companions across the near- to mid-infrared for the first time.

How to cite: Carter, A.: Direct imaging of sub-Jupiter mass exoplanets with James Webb Space Telescope coronagraphy, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-415, https://doi.org/10.5194/epsc2021-415, 2021.

How to cite: Ygouf, M., Beichman, C. A., Rocha, G. M., Green, J. J., Jeffrey B, J., Roudier, G. M., Greenbaum, A., Leisenring, J., Girard, J., Pueyo, L., Perrin, M., Meyer, M., De Furio, M., and Uyama, T.: Realizing the Potential of JWST High Contrast Imaging with Coronagraphic Phase-Retrieval, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-822, https://doi.org/10.5194/epsc2021-822, 2021.

Introduction

The discovery of the first extrasolar planets demonstrated that planets can form around other stars and be detected with current instrumentation. Since more than 200 moons exist in the Solar System, it is expected that they orbit exoplanets as well. Detecting an exomoon could set the next milestone in observations of exoplanetary systems.   

Tidal interactions between planets and their satellites can heat a satellite’s interior. The most evident example is Io, which is the most tidally active body in the Solar System. Since tidal dissipation depends on the orbital and physical properties of the system, if tidal heating is vigorous enough in exoplanetary systems, there is a chance that Tidally Heated Exomoons (THEMs; Peters and Turner 2015) are detectable with current instrumentation and/or the JWST in infrared (IR) wavelengths. As a direct result of tidal heating, spectral signatures of volcanic activity could also be a method of detecting THEMs (Oza et al. 2019). 

Two of the gas giant planet moon systems are in long-lived mean motion resonances (MMR) and it is expected that the latter would prevail in extrasolar systems as well. Taking the Jovian satellites as an archetype for an exomoon system around β Pictoris b, this would mean that an MMR between two or more exomoons would make them detectable for larger timescales, maintaining tidal activity over the lifetime of the system.

β Pictoris is a 23 Myr old star with a distance of 19.44 pc. A ≃10 Mj directly imaged planet is orbiting the star at 9.8 AU (Lagrange et al. 2020). The system is almost edge-on to our line of sight, making β Pictoris b a plausible candidate for the search of THEMs in the IR, through photocenter astrometry of the combined planet and moon (Agol 2015) or by looking for primary and secondary transits of the exomoon.

Methods

We scale up a Galilean satellite system around β Pictoris b in order to investigate which properties make a putative exomoon detectable. We use orbital-thermal coupled models that assume a layered, radially symmetric moon, consisting of a silicate mantle and a liquid core. We assume that heat is transferred via melt advection (Moore 2003) and mantle convection from the interior to the surface and we obtain equilibrium temperatures. We explore the parameter space of orbital and physical properties of an exomoon around β Pictoris b by using different rheological models (Maxwell, Andrade).

Results

Given a semi-major axis and eccentricity for an 8M_Io mass exomoon, we obtain the corresponding interior structure and heat flow through the moon, resulting in a calculated effective temperature at the surface. We present our results for our Andrade rheology model and heat transfer mechanisms (Figure 1) and place constraints on the feasible interior models and orbital parameters for a putative surface heat flux of an exomoon around β Pictoris b. At Io’s orbital eccentricity a 2R_Io exomoon would need to be close to the Roche radius of β Pictoris b to reach 600 K and be observed with the JWST (Figure 2), however this limit relaxes for higher eccentricities and bigger moons. We find that the Andrade rheology results in higher surface temperatures when compared to the basic Maxwell viscoelastic model.

Figure 1: Equilibrium surface temperatures of a 2R_Io exomoon (Super-Io) around β Pictoris b using Andrade rheology and melt advection. The horizontal line shows Io’s orbital eccentricity.

Figure 2: Fluxes at the β Pictoris system. The grey continuous line shows the modeled spectrum of a planet with similar parameters as β Pictoris b (Morley et al. 2015), the dashed black line the blackbody curve of the star and the purple line the one of a Super-Io (2R_Io). The horizontal lines are the 5σ and 10,000s integration time detection limits of MIRI/JWST for various bands (Glasse 2010)).

References

Agol et al. (2015) The Astrophysical Journal, 812(1), p.5.

Glasse (2010) SPIE, 7731, 77310K.

Lagrange et al. (2020) Astronomy & Astrophysics, 642, p.A18.

Moore  (2003) Journal of Geophysical Research, 108(E8).

Morley et al. (2015) The Astrophysical Journal, 815(2), p.110.

Oza et al. (2019) The Astrophysical Journal, 885(2), p.168.

Peters and Turner (2013) The Astrophysical Journal, 769(2), p.98.

How to cite: Kleisioti, E., Dirkx, D., Rovira-Navarro, M., and Kenworthy, M.: Could we observe exomoons around β Pictoris b?, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-546, https://doi.org/10.5194/epsc2021-546, 2021.

PLATO is an ESA mission dedicated to the study of exoplanets and stars, with a planned launch date in 2026. By performing photometric monitoring of about 250 000 bright stars (m_V < 13), PLATO will be able to discover and characterise hundreds of exoplanets, including small planets orbiting up to the habitable zone of solar-like stars. PLATO’s precision will also allow for a precise characterisation of the host stars through asteroseismology. These objectives require both a wide field of view and high sensitivity, which are achieved with a payload comprising 24 cameras with partially overlapping fields of view. They are complemented by 2 more cameras optimised for brighter stars that will also be used as fine guidance sensor. The PLATO development phase started after the mission adoption in July 2017. The Mission Preliminary Design Review (PDR) was declared successful in October 2020. The implementation and delivery to ESA of the flight model CCDs for all cameras (4 CCDs per camera) has been completed. Currently the Structural Thermal Model (STM) of the payload optical bench is being manufactured, while the STM of a single camera has already been successfully tested. In parallel, a first engineering model of a complete, fully functional camera is being integrated, to verify its performance under operational conditions, and the qualification models of the different payload units are being built.

We will present the status of the PLATO payload implementation in the context of the satellite development. In particular, we will describe the payload manufacturing, integration, and tests that will be reviewed at the Critical Milestone in the second half of 2021. We will also summarise the progress made in the science preparation activities, as well as on the ground segment.

How to cite: Rauer, H., Pagano, I., Mas-Hesse, M., Aerts, C., Deleuil, M., Gizon, L., Goupil, M.-J., Heras, A. M., Piotto, G., Pollacco, D., Ragazzoni, R., Ramsay, G., and Udry, S.: The PLATO mission: Overview and status, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-90, https://doi.org/10.5194/epsc2021-90, 2021.

Ariel, the atmospheric remote-sensing infrared exoplanet large-survey, is the recently adopted M4 mission within the Cosmic Vision science programme of ESA. The goal of Ariel is to investigate the atmospheres of planets orbiting distant stars in order to address the fundamental questions on how planetary systems form and evolve and to investigate in unprecedented detail the composition of a large number of exoplanetary atmospheres. During its 4-year mission, Ariel will observe hundreds of exoplanets ranging from Jupiter- and Neptune-size down to super-Earth size, in a wide variety of environments, in the visible and the infrared. The main focus of the mission will be on warm and hot planets in orbits close to their star. Some of the planets may be in the habitable zones of their stars, however. The analysis of Ariel spectra and photometric data will allow to extract the chemical fingerprints of gases and condensates in the planets’ atmospheres, including the elemental composition for the most favourable targets. The Ariel mission has been developed by a consortium of more than 60 institutes from 15 ESA member state countries, including UK, France, Italy, Poland, Spain, the Netherlands, Belgium, Austria, Denmark, Ireland, Hungary, Sweden, Czech Republic, Germany, Portugal, with an additional contribution from NASA. In this talk, we will review the science goals of the mission and give insight into the current status, both from the ESA and the Ariel Mission Consortium point of view.  

How to cite: Lueftinger, T., Tinetti, G., Ecclestone, P., Salvignol, J.-C., Fahmy, S., Lagage, P.-O., Micela, G., Pallé, E., Panic, O., Pascale, E., Vandenbussche, B., and Venot, O.: Ariel - The ESA M4 Space Mission to Focus on the Nature Of Exoplanets, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-610, https://doi.org/10.5194/epsc2021-610, 2021.

Since the very early phases of designing and developing space instruments, we need fast and reliable tools to validate and optimise the projects. In the framework of the Ariel Space Mission, we developed novel, versatile tools to estimate space instruments performance. 

ExoSim, a transiting exoplanet observation simulator, is a time domain simulator for space telescopes, that has been developed inside the Ariel framework, but already adapted to both HST and JWST, proving its versatility and its capability to accurately predict science products. It can be used to develop the data reduction pipeline, and to optimise systematics removal techniques.

ArielRad, the Ariel radiometric model, is a simulator able to accurately predict the telescope performance in observing a candidate target for all the mission photometric and spectroscopic channels. The software inputs are a target description and a parameterization of the payload, allowing the investigation of different design performance. The software is also able to simulate entire target lists, predicting the observing time and the resulting SNR vs wavelength. Analysing 1000 candidate targets in a 20 minutes time scale, it allows the validation of different observational strategies. The software architecture is based on ExoRad 2, that is publicly available and can be easily adapted to perform the same tasks for other future space missions.

How to cite: Mugnai, L. V., Pascale, E., Edwards, B., Papageorgiou, A., and Sarkar, S.: Performance simulations tools for Space Telescopes applied to Ariel space mission., Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-182, https://doi.org/10.5194/epsc2021-182, 2021.

In the next decade, the Ariel Space Telescope will provide the first statistical data set of exoplanet spectra, performing spectroscopic observations of about 1000 exoplanets in the wavelength range 0.5 - 7.8 micron during its Reconnaissance Survey. The Ariel Reconnaissance Survey has been designed specifically to identify planets without molecular features in their atmosphere, and select targets (about 500) for accurate chemical characterisation with higher SNR spectroscopic observations.

In this work, we investigate the information content of Ariel's Reconnaissance Survey low resolution transmission spectra. We produce different planetary populations using the Ariel candidate target list, randomizing the planetary atmospheres, and simulating the Ariel observations using the Alfnoor software. Then we analyse the dataset, getting three different results:

(1) We present a solid strategy that will allow selecting candidate planets to be reobserved in an Ariel's higher resolution, using a chi-squared based metric to identify the flat spectra.

(2) Because the reconnaissance survey is not optimised for spectral retrieval, we propose a novel model-independent metric to preliminary classify exoplanets by their atmospheric composition. Without any other planetary information than the spectrum, our metric proves capable of indicating the presence of a molecule when its abundance in the atmosphere is in excess of 10^-4 in mixing ratio.

(3) We introduce the possibility of finding other methods to better exploit the data scientific content. We report as an example of possible strategies, a preliminary study involving Deep and Machine Learning algorithms. We show that their performance in identifying the presence of a certain molecule in the spectra is marginally better than our metric for some of these algorithms, while others outperform the metric. 

We conclude that the the Ariel reconnaissance survey is effective in detecting exoplanets manifesting featureless spectra, and we further show that the data collected in this observing mode have a rich scientific content, allowing for a first chemical classification of the observed targets.

How to cite: Mugnai, L. V., Al-Refaie, A., Bocchieri, A., Changeat, Q., Pascale, E., and Tinetti, G.: Alfnoor: a population study on Ariel's low resolution transmission spectra., Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-185, https://doi.org/10.5194/epsc2021-185, 2021.

Ariel, the Atmospheric Remote-sensing Infrared Exoplanet Large-survey, is a medium-class space mission part of ESA's Cosmic Vision programme, due for launch in 2029. Ariel will survey a diverse sample of about 1000 extrasolar planets in the visible and infrared spectrum to answer questions about their composition, formation and evolution. Ariel mounts an off-axis Cassegrain telescope with an 1100 mm x 730 mm elliptical mirror and has two separate instruments (FGS and AIRS) that cover the 0.5-7.8 micron spectral range. To study the Ariel optical performance and related systematics, we developed PAOS, the Physical Ariel Optics Simulator, an End-to-End physical optics propagation model of the Ariel Telescope and subsystems. PAOS is a Python code that consists of a series of functions and procedures that reproduces the Ariel optical design. Using PAOS, we can investigate how diffraction affects the electromagnetic wavefront as it travels through the Ariel optical systems and the resulting PSFs in the photometric and spectroscopic channels of the mission. This enables to perform a large number of detailed analyses, both on the instrument side and on the optimisation of the Ariel mission. In particular, PAOS can be used to support the requirement on the maximum amplitude of the aberrations for the manufacturing of the Ariel primary mirror, as well as to develop strategies for in-flight calibration, e.g. focussing procedures for the FGS and AIRS focal planes, and to tackle systematics such as pointing jitter and vignetting. With the Ariel mission now in the process of finalizing the instrument design and the data analysis techniques, PAOS will greatly contribute in evaluating the Ariel payload performance with models to be included in the existing Ariel simulators such as ArielRad, the Ariel Radiometric model, and ExoSim, the Exoplanet Observation simulator, for the purpose of studying and optimising the science return from Ariel.

How to cite: Bocchieri, A. and Pascale, E.: PAOS, the Physical Optics Propagation model of the Ariel optical system, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-241, https://doi.org/10.5194/epsc2021-241, 2021.

After JWST, NASA’s next flagship astrophysics mission is the ambitious Nancy Grace Roman Space Telescope. Roman will include the Coronagraph Instrument (CGI) will be the first high-performance stellar coronagraph using active wavefront control for deep starlight suppression in space, providing unprecedented levels of contrast, spatial resolution, and sensitivity for astronomical observations in the optical. During its Technology Demonstration phase, CGI will resolve the signal of an exoplanet via photometry and spectroscopy and directly image and measure the polarization of disks. Future flagship mission concepts (e.g., HabEx and LUVOIR) aim to characterize Earth analogues with visible light flux ratios of ~10^-10, and CGI is a critical intermediate step toward that goal, with predicted capability of ~10^-9. Here, we present CGI’s design and capability as well as some anticipated results from its technology demonstration.

How to cite: Zellem, R.: Overview of the Nancy Grace Roman Space Telescope Coronagraph Instrument and Its Technology Demonstration, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-421, https://doi.org/10.5194/epsc2021-421, 2021.

As the Kepler mission has done for hot exoplanets, the ESA Euclid and NASA Roman missions have the potential to create a breakthrough in our understanding of the demographics of cool exoplanets, including planets on very wide orbits, unbound, or "free-floating", planets (FFPs). Current ground-based microlensing observations have provided preliminary evidence for a potentially significant population of Super-Earth FFPs. Roman will dedicate part of its core survey program to the detection of cool exoplanets via microlensing, while Euclid may undertake a microlensing program as an ancillary science goal. We argue that simultaneous observations of short-duration microlensing events by Roman and Euclid will enable not just the verification of FFPs, but also a direct measurement of their masses, distances and transverse motions, via the detection of microlens parallax between Euclid and Roman. We use simulations of the joint-mission detection capabilities to show that parallax detections will be possible down to Earth-mass FFPs. The mass and phase-space measurements from a joint survey could thus provide strong clues to the primary mode of FFP formation.

We also demonstrate that an early brief Euclid survey (∼5 h) of the Roman fields shortly after the Euclid launch would be also very valuable. It would allow the measurement of at least 10% of the events’  relative proper motions and 35% of the lens magnitudes very early on the life of the Roman Survey. We further discuss additional valuable science that will be facilitated by a joint Roman-Euclid microlensing campaign.

How to cite: Beaulieu, J.-P. and Bachelet, E.: Microlensing survey combining  Roman and Euclid Space Telescopes, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-298, https://doi.org/10.5194/epsc2021-298, 2021.

Abstract

The coronagraph instrument aboard the Nancy Grace Roman Space Telescope is a technology demonstrator that will perform the first reflected-starlight direct imaging observations of exoplanets. This instrument will pave the way for future missions such as LUVOIR or HabEx, which have the goal of characterizing the atmospheres of Earth-like exoplanets. In this work we develop a statistical method to compute which of the confirmed exoplanets in the NASA Exoplanet Archive would be accessible in reflected starlight to a direct-imaging telescope. By applying our method to the Roman Telescope’s coronagraph, we show that an eventual science phase of the Roman Telescope’s coronagraph has a remarkable potential to study cold and temperate exoplanets and initiate their atmospheric characterization.

Introduction

The years until the expected launch of the Roman Telescope^[1] in 2025 should be used to improve the orbital characterization of the most interesting targets through radial velocity or astrometry campaigns. For this, a target list of known exoplanets that could be observed with the Roman Telescope’s coronagraph is needed. Additional figures describing the detectability and scientific interest of each accessible exoplanet are useful to prioritize the observations of the targets.

Statistical method

We use the NASA Exoplanet Archive^[2] as the main source of information for the planetary and stellar properties of each of the about 4300 confirmed exoplanets. For each exoplanet, we compute 10,000 orbital realizations letting each of the parameters involved vary within its reported upper and lower uncertainties. When the orbital inclination (i), the eccentricity (e) or the argument of periastron of the planet (ω_p) are unconstrained, we randomly draw their value at each orbital realization from uniform distributions. When the planet radius is unknown, we compute it by means of published mass-radius relationships^[3][4]. By discretizing each orbital realization into 360 positions, we compute at each position the angular separation between the planet and the star (Δθ) and the planet-to-star contrast ratio (F_p/F_*). We define a planet as Roman-accessible if at a certain orbital position its angular separation is within the inner and the outer working angles (IWA, OWA) of the coronagraph and, additionally, the planet-to-star contrast is brighter than the minimum contrast (C_min) that the coronagraph can detect.

Our main outputs are the probability of a planet to be Roman-accessible (P_access), the range of observable phase angles (α_obs), the number of days per orbit in which the planet is accessible (t_obs) and its transit probability. Due to its interest for atmospheric modelling, we also compute the equilibrium temperature (T_eq) at each orbital position. This allows us to compute the mean value of T_eq throughout the orbit, its variation due to orbital eccentricity and the variation of T_eq that takes place while the planet is accessible, which could result in detectable atmospheric variability.

With this method, we computed the accessibility of each planet at wavelengths 575, 730 and 825 nm, consistent with the coronagraph filters that are currently commissioned. We repeated this study for three plausible configurations of the coronagraph because its final design is not yet completed. We label these configurations as optimistic (IWA=3λ/D, OWA=9λ/D, C_min=1×10⁻⁹), intermediate (IWA=3.5λ/D, OWA=8.5λ/D, C_min=3×10⁻⁹) and pessimistic (IWA=4λ/D, OWA=8λ/D, C_min=5×10⁻⁹).

Results

We find up to 26 exoplanets Roman-accessible exoplanets in the optimistic scenario with P_access>25% and orbiting stars brighter than V=7 mag^[5]. We apply the latter two vetting criteria throughout our work due to the particular constraints of the Roman Telescope mission timeline and the sensitivity of its coronagraph instrument. This number of Roman-accessible exoplanets is reduced to 10 and 3 in the intermediate and pessimistic scenarios, respectively.

For the Roman-accessible exoplanets in the optimistic scenario we carried out a population study and found that this set of planets is dominated by giant exoplanets more massive than Jupiter. Interestingly, it also includes the low-mass planets tau Cet e and f, which orbit near the habitable zone of their host star. These two planets are however barely accessible in the intermediate or pessimistic coronagraph scenarios (Fig. 1). Thirteen of the 26 Roman-accessible exoplanets are part of multi-planet systems and three of them have inner companions observed in transit, which would enable the simultaneous characterization of the inner and the outer regions of these planetary systems. The mean equilibrium temperatures of the Roman-accessible planets range from values in the order of that of Uranus to values above 400 K, including some targets at ~300 K (Fig. 2).

For a selection of particularly interesting targets, we analysed in more detail the prospects for observing and eventually characterizing these planets. For instance, we discussed how the detectability prospects may change if additional constraints on the orbital inclination are set e.g. with astrometry (Fig. 1).

We find some exoplanets with remarkably wide ranges of observable phase angles, which makes them interesting for atmospheric characterization with reflected-starlight phase curves^[6]. In this regard, we also discussed the importance of consistently reporting the planet and stellar parameters in exoplanet catalogues such as the NASA Archive and the misleading detectability results that might be achieved if an A standardization process is not performed.

Overall, we find that a science phase of the Roman Telescope’s coronagraph would have an extraordinary potential to perform one-of-a-kind observations before next-generation missions that are not expected at least until the mid-2030s.

References

[1] Spergel et al. (2013), https://arxiv.org/abs/1305.5422
[2] Akeson et al. (2013), PASP, 125, 989
[3] Hatzes & Rauer (2015), ApJL, 810, L25
[4] Otegi et al. (2020), A&A, 634, A43
[5] Carrión-González et al. (2021), A&A accepted
[6] Carrión-González et al. (2021), in prep.

How to cite: Carrión-González, Ó., García Muñoz, A., Santos, N. C., Cabrera, J., Csizmadia, S., and Rauer, H.: A catalogue of up to 26 known exoplanets accessible to reflected-starlight observations with the Roman Space Telescope, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-772, https://doi.org/10.5194/epsc2021-772, 2021.

Summary

The Large Interferometer For Exoplanets (LIFE) mission concept is a project initiated in Europe with the goal to consolidate various efforts and define a road map that eventually leads to the launch of a large, space-based mid-infrared (MIR) nulling interferometer observatory. This mission will be able to investigate the atmospheric properties of a large sample of  terrestrial, potentially habitable exoplanets. In this contribution we present a status report and summarize new results from the LIFE Mission initiative. 

Context

One of the major goals of exoplanetary science and possibly the most challenging question in 21st century exoplanet research is the investigation of the atmospheric properties for a large number (~100) of terrestrial exoplanets. This is only partially driven by the idea to search for habitable conditions and identify potential biosignatures, since such a statistically significant data-set is - in a more general sense - invaluable for understanding the diversity of planetary bodies. First steps in this direction will be taken in the coming 10-15 years with funded or selected ground- and space-based projects and missions. And while exoplanet science is omnipresent on the road maps of all major space agencies, none of them will be able to deliver such a comprehensive and consistent, big data set. An alternative to the mainly discussed large space-based coronographic missions or the starshade concept is to separate the light emitted by the planet from that of its host star by means of an interferometer.
In this contribution we summarize new results from the LIFE Mission initiative, which addresses this issue by investigating the scientific potential and technological challenges of an ambitious mission employing a formation-flying nulling interferometer in space working at mid-infrared wavelengths [1,2,3]. Centered around clear and ambitious scientific objectives the project will define the relevant science and technical requirements. The status of key technologies will be re-assessed and further technology development will be coordinated. LIFE is based on the heritage of ESA/Darwin and NASA/TPF-I, but significant advances in our understanding of exoplanets and newly available technologies will be taken into account in the LIFE mission concept. Advances in our knowledge of the exoplanet population as well as significant progress in relevant technologies justify the need, but also the feasibility for a future mission like LIFE to investigate one of the most fundamental questions of mankind: How unique is the phenomenon we call life in the universe?

Artist's impression of the LIFE concept.

New Results and Progress

Over the past year the LIFE community grew significantly into an initiative with more than 100 collaborators from all over the world. We will present the current structure of teams and working groups and the lead personnel in these.

Furthermore we will summarize a number of new science results (other LIFE contributions to this conference in brackets):

• an updated yield estimate for the LIFE mission ([4], see also Kammerer et al. 2021, this conference), where we used simulations based on Kepler statistics to demonstrate that a MIR space-based nulling interferometer like LIFE could yield at least as many exoplanet detections as a large, single aperture optical/NIR telescope.
• the release of our simulator software LIFEsim that incorporates various telescope sizes and a new noise model that takes into account all astrophysical noise sources. This enables us to systematically study our mission requirements in order to optimize our observing strategy ([5], Dannert et al 2021, this conference).
• in two other submission (Alei et al. 2021, Konrad et al. 2021, this conference) we discuss  how our spectral retrieval routine performs when attempting retrievals of terrestrial exoplanets, using case scenarios like the Earth in Time and Venus.
• a study on the search for phosphine in various exoplanetary contexts [6], that also serves guidance for  the community by providing easy-to-scale first estimates for a large part of detection space of such a mission

Outlook

Besides various activities on the technology side, defining the auxiliary science and in other working groups we are currently focusing on a detailed simulation of the impact on scheduling for the survey and characterisation phases of the LIFE mission. In this context we are also investigating modern machine learning methods that are crucial to scale up front to end simulations of the full LIFE survey. This in turn will not only inform the aforementioned scheduling consideration but also help to define sensitivity, wavelength coverage and spectral resolution requirements on the technology side.

References

[1] Quanz, S. P., Kammerer, J., Defrère, D., et al. 2018, Optical and Infrared Interferometry and Imaging VI,10701,107011I.

[2] Defrère, D., Léger, A., Absil, O., et al. 2018, Experimental Astronomy, 46, 543.

[3] Quanz,S.P., et al.2019.,arXive-printsarXiv:1908.01316.

[4] Quanz, S.P., Ottiger, M., Fontanet, E., et al. 2021,arXiv:2101.07500

[5] Ottiger, M., et al. : Large Interferometer For Exo-planets (LIFE):II. Signal simulation, signal extraction andfundamental exoplanet parameters from single epoch ob-servations, 2021 (in prep.)

[6] Angerhausen, D., et al. : Large Interferometer ForExoplanets (LIFE): IV. Where is the phosphine?Observing exoplanetary PH3 with a space based MIRnulling interferometer, 2021 (in prep.)

How to cite: Angerhausen, D. and Quanz, S. and the LIFE collaboration: The Large Interferometer For Exoplanets (LIFE) mission: status and progress report, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-284, https://doi.org/10.5194/epsc2021-284, 2021.

Context: Warm, terrestrial exoplanets represent a key component in the exoplanet population when exploring the diversity of planets and investigating the properties of potentially habitable worlds [1]. Subsequently, the LIFE Collaboration is presenting a mission concept for the Large Interferometer for Exoplanets (LIFE) capable of directly imaging the thermal emission of terrestrial exoplanets in the mid-infrared using the technique of nulling interferometry [2]. Since LIFE will explore the previously disfavored parameter-space of mature planets close to their host stars, it needs to spend 2.5 yrs of its 5 yrs mission on detecting previously inaccessible planets. This so-called search phase will provide the sample of exoplanets from which suitable targets for in-depth follow-up observations will be selected. The scientific success of the mission hinges on its capacity to observe a sufficiently large sample of potentially habitable worlds to allow for the formulation of statistically significant results regarding the existence of life in the Universe. These kinds of results are further needed to constrain exoplanet populations and make results comparable to theoretical predictions.

Aim: We aim to predict the exoplanet yield of the LIFE mission search phase in total numbers of detected planets and properties of the planetary sample. Our predictions are based on the assumption of the measurement principle of LIFE and all pertinent astrophysical sources of noise (stellar leakage, local zodiacal, and exozodiacal dust) degrading the quality of the measurements. While our current simulations only account for random background noise, we aim to include an implementation of instrumental noise sources once a preliminary mission design has been developed.

Methods: The prediction of the search phase yield can be subdivided into three steps. First, a catalog of nearby stars [2] is populated with synthetic planets drawn based on Kepler statistics [3]. For each of these planets, a nulling inteferometric observation with LIFE is simulated under the assumption of the astrophysical noise contributions mentioned above. Lastly, the time available in the search phase is distributed among the targets such that the total number of detected planets is maximised.

Results: We predict that LIFE will be able to detect roughly 230 terrestrial exoplanets within the 2.5 yrs search phase. Figure 1 shows the distribution of this sample in the planet radius and insolation plane. LIFE will be most efficient in finding warm, super-Earth-sized planets (as defined in [4]), but enables detections ranging from 0.5-6 R_⊕ in radius and 10^-1-10³ S_⊕. We find that the exoplanet yield is a strong function of the mirror size and that the uncertainties are dominated by uncertainties in the underlying planet population.

We show that the properties of the exoplanet sample do not only depend on the characteristics of the instrument, but furthermore on the distribution of the available observing time among stellar targets. Figure 2 demonstrates that a distribution optimized towards detecting planets in the habitable zone of their parent star (scenario 2) can increase the total number of these potentially habitable planets by ~60%. However, such optimizations come at the cost of a reduced number of detections in other planet categories.

Depending on the optimization scenario, 27-43 of the detected planets will reside in the empirical habitable zone [5] of their host stars. This is thought to be a sufficient number of planets to effectively constrain the ratio of terrestrial planets in the habitable zone which provide conditions for liquid water to exist on their surface [6]. Since a significant fraction of these planets will be around M-type stars, a discussion of the habitability potential in those conditions [7] needs to be revised with the help of JWST observations.

The value that the LIFE mission will add to the sample of known exoplanets is significant. Figure 3 demonstrates how the detection capability of LIFE for terrestrial exoplanets reaches to significantly smaller planets, covering the region in parameters space occupied by the four terrestrial planets in the Solar System. We are able to demonstrate that in terms of number of detections, LIFE will provide a potential similar to that of the LUVOIR concept and superior to that of the HabEx concept. Lastly, we raise the following discussion point: We have shown that the number of predicted detections depends not only on the instrument performance, but also on the underlying synthetic exoplanet sample and the distribution of the observing time. Since the assumptions for the latter two points likely deviate between mission concepts, we reiterate a performance measure which can decouple and display the instrument performance.

References:
[1] Committee on Exoplanet Science Strategy: NASA Exoplanet Science Strategy, The National Academy of Sciences, 2018
[2] LIFE Collaboration et al.: Large Interferometer For Exoplanets (LIFE): I. Improved exoplanet detection yield estimates for a large mid-infrared space-interferometer mission, arXiv, 2021
[3] Kammerer, Jens, and Quanz, Sascha P.: Simulating the Exoplanet Yield of a Space-Based Mid-Infrared Interferometer Based on Kepler Statistics, Astronomy and Astrophysics, Vol. 609, 2018
[4] Kopparapu, Ravi Kumar, et al.: Exoplanet Classification and Yield Estimates for Direct Imaging Missions, The Astrophysical Journal, Vol. 856, 2018
[5] Kopparapu, Ravi Kumar, et al.: Habitable Zones around Main-Sequence Stars: Dependence on Planetary Mass, The Astrophysical Journal Letters, Vol. 787, 2014
[6] Quanz, Sascha P., et al.: Atmospheric Characterization of Terrestrial Exoplanets in the Mid-Infrared: Biosignatures, Habitability & Diversity, ESA Voyage 2050 White Paper, arXiv, 2019
[7] Shields, Aomawa L., et al.: The habitability of planets orbiting M-dwarf stars, Physics Reports, Vol. 663, 2016

How to cite: Kammerer, J., Dannert, F., Quanz, S., and Angerhausen, D. and the LIFE Collaboration: Exoplanet yield predictions for the future LIFE mission, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-328, https://doi.org/10.5194/epsc2021-328, 2021.

Context

The Large Interferometer for Exoplanets (LIFE) is a proposed future space mission enabling mid-infrared direct imaging observations of a large number of temperate terrestrial exoplanets. LIFE will be developed to answer a specific set of science objectives¹ concerning the atmospheres and habitability of exoplanets. To have a successful mission, it is vital that these scientific requirements are sufficiently well translated into technical requirements based on which the instrument can be designed. Similarly, technical constraints might impact the scientific capabilities of the mission. 

LIFEsim² is a custom-built science simulator software for LIFE which aids in exactly this communication between the scientific and technical aspects of the mission design.

Aim

We aim to present the simulation pipeline as well as the technical and physical assumptions used in the current generation of the LIFE simulator. In its current development state, LIFEsim is capable of simulating nulling interferometric spectral observations of single targets accounting for all relevant astrophysical noise terms as well as predicting the total number and properties of exoplanet detections expected given a pre-defined optimization strategy (e.g., maximizing the yield of Earth-like exoplanets).

Simulator Pipeline

Artificial Planet Population

LIFE will discover many planets in a radius and insolation parameter space which is inaccessible by current instruments. To correctly predict the number of detections in this region of parameter space, it is necessary to create a sample of artificial exoplanets. We start with a star catalog containing real single and wide (>20 au) binary main-sequence stars within the next 20 pc. These stars are then populated with synthetic exoplanets based on occurrence rates from the Kepler mission. This step is facilitated using P-Pop (Kammerer et al., 2018). In a Monte-Carlo approach, we simulate 500 different universes.

Instrument Simulation

A nulling interferometer aims to achieve two goals. It blocks the light of the central star by placing it in a destructive interferometric fringe and, by rotation of the instrument, it dissociates between symmetric and asymmetric signals around the star. To simulate this behaviour, we calculate the interferometric fringe pattern (the transmission map, see Figure 1) of a double Bracewell interferometer capturing the response of the instrument to on-sky signals (Ottiger et al., 2021).

Noise Sources

Several astrophysical noise sources complicate the detection of exoplanets with LIFE. The non-zero apparent extend of the host star contributes photons under the sinusoidal shape of the transmission map. Zodiacal dust in the target system extends even further out from the star. It is heated by the star and therefore contributes to the measurement at wavelengths similar to the thermal emission of terrestrial exoplanets. Lastly, because LIFE will be located at the Earth-Sun L2-point, targets have to be viewed through the thermal emission of the local-zodiacal dust cloud in the solar system. These noise contributions are modeled and propagated in LIFEsim. In the current state, LIFEsim does not account for instrumental noise. This implies that the current simulations treat LIFE as operating in the background-limited case. While the goal for LIFE is to operate in this regime, future work will aim to include instrumental noise effects in the simulation.

Observation Time Optimization

The LIFE mission will allocate a specific amount of time (2.5 yrs) to the detection of previously unknown exoplanets. This time needs to be distributed among the star systems. We present observing sequences optimized for either the maximum number of detected exoplanets or for the maximum number of detected terrestrial exoplanets which reside in the empirical habitable zone (Kaltenegger, 2017) of their respective host star. Improving on Lawson et al. (2007), we present an optimization method in which the systems are ranked according to their efficiency measured in number of detected planets per observation time spend on the system. Additionally, we present a trade-off between the total number of observed exoplanets and the completeness to which the individual systems are observed using a method suggested in Stark et al. (2014).

Results

We report that LIFEsim is able to simulate exoplanet detection yields and single spectral observations for the LIFE mission in the background limited case. 
The scientific implications of the predicted exoplanet yield (Kammerer et al. 2021, this conference) and the spectral retrieval of planetary atmospheres (Alei et al. 2021, Konrad et al. 2021, this conference) are discussed in separate talk submissions to this conference.

____________________

¹ https://www.life-space-mission.com/the-project/science/

² The LIFEsim tool is publicly available at https://github.com/fdannert/LIFEsim

References

Kammerer, Jens, and Quanz, Sascha P. : "Simulating the Exoplanet Yield of a Space-Based Mid-Infrared Interferometer Based on Kepler Statistics", Astronomy and Astrophysics, vol. 609, 2018

Ottiger, Maurice, et al. : "Large Interferometer For Exoplanets(LIFE):II. Signal simulation, signal extraction and fundamental exoplanet parameters from single epoch observations", 2021 (in prep.)

Kaltenegger, Lisa. "How to Characterize Habitable Worlds and Signs of Life." Annual Review of Astronomy and Astrophysics, vol. 55, 2017

Lawson, P. R., et al. "Terrestrial Planet Finder Interferometer: 2006-2007 Progress and Plans." Techniques and Instrumentation for Detection of Exoplanets III, vol. 6693, March, 2007

Stark, Christopher C., et al. "Maximizing the ExoEarth Candidate Yield from a Future Direct Imaging Mission." Astrophysical Journal, vol. 795, no. 2, 2014

How to cite: Dannert, F., Kammerer, J., Angerhausen, D., and Quanz, S. P. and the LIFE collaboration: LIFEsim: Methods for predicting the capability of the future LIFE mission, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-326, https://doi.org/10.5194/epsc2021-326, 2021.

EXCITE is a balloon-borne near-infrared spectrometer designed to observe from 0.6 to 4 micron and to perform phase-resolved spectroscopy of hot Jupiters during a Long-Duration Balloon (LDB) flight from Antarctica in 2024.  These spectral measurements probe varying depths in exoplanets atmospheres thus contributing to our understanding into atmospheric physics, chemistry and circulation.  

EXCITE uses a commercially available 0.5 m diameter telescope, coupled to a cooled spectrometer, and pointed with high accuracy and stability using the successful Balloon Imaging Testbed (BIT) pointing platform.  The combination of these elements results in a unique instrument for exoplanet atmospheric characterization. 

EXCITE will measure spectroscopic phase curves of bright, short-period extrasolar giant planets over full orbital. Hot Jupiters provide an ideal laboratory for understanding atmospheric dynamics and the resulting phase-resolved spectroscopy maps the temperature profile and chemical composition of the planet as a function of planetary longitude. The wavelength range covers the peak in the planet’s spectral energy distribution  and H2, CO2 , CO, CH4 , TiO and VO spectral features. These data, combined with state-of-the-art 3D general circulation models (GCMs), will be used to study the atmospheric dynamics and chemistry in these strongly-irradiated planets. This  will allow us to refine these models and improve their predictive power. Ultimately, the spectroscopic phase curves obtained from EXCITE can be used to study the links between the atmospheric properties of hot Jupiters and their formation, bulk properties, orbital dynamics and environment. The LDB flight of EXCITE will fulfill a critical need as the first dedicated instrument for exoplanet atmospheric characterization in the current decade.

EXCITE will use mostly off-the-shelf components. A schematic of the optics layout is shown in the diagram below (credit L. Mugnai). Ambient temperature optics include the telescope, which has a diameter of 0.5 m. One dichroic filter (D1) transmits wavelengths shorter than 1 micron and reflects longer wavelengths. The transmitted light is used to feed a fine pointing photometric camera (FGS) that provides the telescope attitude error. Infrared light propagates through the cold optics (< 120K) inside a long duration cryostat and it is dispersed by a prism.  Light is further split into two channels. Channel 1, covering the  1 to 2.5 micron region of the electromagnetic spectrum, and Channel 2 from 2.5 to 4 micron. A single, cold field-stop (slit) is placed at the prime focus to limit radiative backgrounds.

The two spectrometric channels are designed to achieve a spectral resolving power larger than 50.  Both spectrometers are imaged onto a single Teledyne H1RG detector , read through the ASIC for Control And Digitization of Imagers for Astronomy (ACADIA) detector controller that was developed for the Nancy Grace Roman Space Telescope (NGRST).. Detector and cold optics are operated at cryogenic temperatures using two mechanical cryocoolers. EXCITE will use a pointing system similar to that previously flown on Super-BIT. The achieved stability of the line-of-sight is better than 100 milli-arcsec. 

In this presentation I will review the instrument design and the status of the project which schedules a test flight from North America in 2023, and a science LDB flight in December 2024. 

How to cite: Pascale, E., Butler, N., Nagler, P., Netterfield, C. B., Tucker, G., and EXCITE collaboration, T.: The EXoplanet Climate Infrared TElescope - EXCITE, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-98, https://doi.org/10.5194/epsc2021-98, 2021.

Observing planetary auroral radio emission is the most promising method to detect exoplanetary magnetic fields, the knowledge of which will provide valuable insights into the planet's interior structure, atmospheric escape, and habitability. We present LOFAR-LBA circularly polarized beamformed observations of the exoplanetary systems 55 Cancri, υ Andromedae, and τ Boötis. We tentatively detect circularly polarized bursty emission from the τ Boötis system in the range 14-21 MHz with a flux density of ∼890 mJy and with a significance of ∼3σ. For this detection, no signal is seen in the OFF-beams, and we do not find any potential causes which might cause false positives. We also tentatively detect slowly variable circularly polarized emission from τ Boötis in the range 21-30 MHz with a flux density of ∼400 mJy and with a statistical significance of >8σ. The slow emission is structured in the time-frequency plane and shows an excess in the ON-beam with respect to the two simultaneous OFF-beams. Close examination casts some doubts on the reality of the slowly varying signal. We discuss in detail all the arguments for and against an actual detection. Furthermore, a ∼2σ marginal signal is found from the υ Andromedae system and no signal is detected from the 55 Cancri system. Assuming the detected signals are real, we discuss their potential origin. Their source probably is the τ Bootis planetary system, and a possible explanation is radio emission from the exoplanet τ Bootis b via the cyclotron maser mechanism. Assuming a planetary origin, we derived limits for the planetary polar surface magnetic field strength, finding values compatible with theoretical predictions. Further low-frequency observations are required to confirm this possible first detection of an exoplanetary radio signal.

How to cite: Turner, J., Zarka, P., Griessmeier, J.-M., Lazio, J., Cecconi, B., Enriquez, J. E., Girard, J., Jayawardhana, R., Lamy, L., Nichols, J., and de Pater, I.: The search for radio emission from the exoplanetary systems 55 Cancri, Upsilon Andromedae, and Tau Bootis using LOFAR beam-formed observations, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-430, https://doi.org/10.5194/epsc2021-430, 2021.

ABSTRACT

GIARPS (GIAno & haRPS) is an observing mode that allows having on the same focal station of the Telescopio Nazionale Galileo (TNG) both the high-resolution spectrographs, HARPS–N (visible, VIS) and GIANO–B (near-Infrared, NIR), working simultaneously. To date, GIARPS is the first and unique worldwide instrument providing cross-dispersed echelle spectroscopy at R= 50,000 in the NIR and 115,000 in the VIS over a wide spectral range (0.383−2.45 μm) in a single exposure. GIARPS is online since 2017 and it is used in a wide range of science cases, especially for the search of exoplanets around young and active stars and the characterization of their atmosphere. In the next future, it will be equipped with NIR absorbing cells to obtain high precision radial velocity (RV). Furthermore, a solar telescope (LOCNES, D=10 cm) will allow the use of GIANO-B to study NIR spectra of the Sun-like-a-star to have more hints on the influence of activity on RV and transmission spectroscopy.

1. GIARPS

GIARPS (Claudi et al 2017) is a TNG observing allowing the simultaneous use of the HARPS-N and GIANO-B spectrographs, exploiting a wide wavelength range (0.383 - 2.45 µm) with high-resolution (115,000 in the visible, 50,000 in the NIR) in a single exposure. GIARPS is the result of the refurbishment of GIANO from a fiber-fed spectrograph to GIANO-B directly fed by the same Nasmyth-B focus feeding HARPS-N, by means of a preslit.

The light coming from the Nasmyth-B focus meets a dichroic that reflects the visible toward HARPS-N and transmits the NIR to GIANO-B. The dichroic is mounted on a motorized slide to select the preferred observing mode.

GIANO-B dewar is rigidly connected to the fork of the TNG and does not add vibration modes to those generated by the telescope (jitter, tracking etc.). For the time being, GIARPS uses both the instruments for high precision radial velocity measurements exploiting the simultaneous reference technique with HARPS-N (Th–lamps) and GIANO-B (telluric lines) reaching in the NIR about 10 m\s for bright stars (H≤5 mag) and 70 m\s (H~9 mag). In future, it will be equipped with absorption cells (acethylene, ammonia and methane) to reach the better precision of 3 m/s.

2. SCIENTIFIC RESULTS

2.1 EXOPLANETARY SCIENCE

In the last few years, several works reported the contribution of GIARPS in the field of the search and characterization of extrasolar planets.

The simultaneous RV collection in the VIS and NIR band allows discriminating between planetary and stellar signals, being the latter wavelength-dependent.

Carleo et al. (2018) made use of several NIR RVs to rule-out the hot Jupiter around the 150 Myr old star BD+201790. With a similar method, in the framework of the GAPS2 program, Carleo et al. (2020) confirmed the presence of a hot Jupiter around the Hyades member HD285507 and demonstrated that the previously detected RV signal around AD Leo has stellar origin.

GIARPS also provides suitable data for the atmospheric characterization of exoplanets. Guilluy et al. (2020) performed high-resolution transmission spectroscopy of the transiting hot Jupiter HD189733b aiming to detect the absorption signal of the helium triplet at 1083.3 nm, an useful diagnostic for extended and escaping atmospheres. They confirmed the result by comparing the helium feature with the one of the Halpha in the VIS to evaluate the stellar activity impact on the planetary absorption.

Finally, Baratella et al. (2020) analysed a sample of intermediate-age stars (<700 Myr) to evaluate their atmospheric parameters and chemical composition both in VIS and NIR bands, by using a new spectroscopic method that uses titanium lines to overcome issues related to the young ages of the stars.

2.2 OTHER SCIENCE

Massi et al. (2019) combining GIARPS spectra with the high spatial resolution of GRAVITY, obtained a view of the innermost regions of circumstellar discs in YSOs modelling the accretion and ejection mechanisms.

The characterization of the star–disk interaction region of CTT in the Taurus-Auriga star-forming region is the main target of GHOsT project (Giannini et al 2019; Gangi et al. 2020). They analyzed the kinematic statistical properties of the [O I] 630 nm and H₂ 2.12 μm lines and their mutual relationship. The results suggest that molecular and neutral atomic emission in disk winds originate from regions that might overlap, with the survival of molecular winds in disks depending on the gas exposure to the star irradiation.

SPA (Origlia et al 2019) is an ongoing GIARPS large program with the aim to perform an age-resolved chemical map of the solar neighborhood and the Galactic thin disk. More than 500 stars, covering different distances, ages and evolutionary stages, will be observed. Frasca et al. (2019) for the ASCC 123 cluster, and D’Orazi et al. (2020) for Hyades and Praesepe derived the stellar parameters, extinction, radial, and projected rotational velocities, and chemical abundances. They found that Praesepe ([Fe/H]=+0.21±0.01 dex ) is more metal-rich than the Hyades (Δ[Fe/H]=+0.05±0.01 dex).

3. CONCLUSION

Since Fall 2017, GIARPS works routinely at the TNG. Thanks to its wide wavelength range it is unique in the northern hemisphere and up to the commissioning of NIRPS at the 3.6m ESO Telescope, the unique in this world. The search for extrasolar planets and the study of stellar populations are the major science cases. Furthermore, the range of GIARPS partially overlap the range of ARIEL suggesting a possible synergy with this space mission dedicated to the study of exoplanetary atmospheres.

REFERENCES

• Baratella et al. 2020, A&A, 640, A123
• Carleo et al. 2018, A&A, 613, A50
• Carleo et al. 2020, A&A 638, A5
• Claudi et al 2017, EPJP, 132, 364
• D'Orazi et al., 2020, A&A, 633, A38
• Frasca et al 2019,  A&A, 632, A16
• Gangi et al. 2020, A&A, 634, A32
• Giannini et al., 2019, A&A, 631, A44
• Guilluy et al. 2020, A&A, 639, A49
• Massi et al. 2019 in “JET Simulations, Experiments, and Theory: Ten Years After JETSET. What Is Next?” Ed. C. Sauty, p.133, Doi: K55-7873
• Origlia et al., 2019, A&A, 629, A117

How to cite: Benatti, S., Claudi, R., and Ghedina, A.: The first four years of GIARPS@TNG Observations, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-486, https://doi.org/10.5194/epsc2021-486, 2021.

The Near-InfraRed Planet Searcher (NIRPS) is designed to be an ultra-stable infrared spectrograph to be installed on ESO’s 3.6 m Telescope in La Silla, Chile. NIRPS is an adaptive optics (AO) fiber-fed spectrograph operating from 0.98 to 1.8 μm and will be operated simultaneously with the optical high-resolution spectrograph HARPS. NIRPS can operate in two modes fed by two different fiber links permanently mounted at the Cassegrain focus that use either 0.4 arcsecond-fibers for the High Accuracy Mode (HAM) or 0.9 arcsecond-fibers for the High Efficiency Mode (HEM). The wavelength range of NIRPS is optimal for low-mass M dwarfs and the simultaneous NIRPS and HARPS observations will improve stellar activity filtering methods given their different wavelength coverages. The NIRPS front-end and AO system were already tested on-sky at La Silla. The spectrograph and back-end is being shipped to La Silla and installed in Summer/Fall 2021. Already we have adapted the state-of-the-art ESPRESSO data reduction pipeline for NIRPS, obtained accurate wavelength solutions with a Uranium Neon lamp, and obtained drift stability results below 50 cm/s with a Fabry–Pérot etalon. We discuss the current and expected instrument performance and the expected results of NIRPS.

How to cite: Grieves, N., Bouchy, F., Doyon, R., Artigau, E., Malo, L., Sosnowska, D., Wildi, F., Blind, N., Sordet, M., and Segovia, A.: NIRPS: the Near-InfraRed Planet Searcher joining HARPS on the 3.6-m, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-555, https://doi.org/10.5194/epsc2021-555, 2021.

Over the last decade, the use of ground-based high-resolution spectrographs has tremendously increased. Such instruments can resolve individual atomic and molecular lines. Therefore, molecular bands observed at low resolution are seen as a forest of millions of lines at high resolution. The advantages of high spectral resolution for atmospheric characterization are multiple. Firstly, it is possible to easily distinguish between different species thanks to their unique spectral fingerprint. Secondly, it is possible to determine the rest frame (e.g., planetary, stellar, Earth) where the lines are formed. The differences in Doppler shifts between planetary, stellar, and telluric lines allow high-resolution observations to achieve robust atmospheric detections. Moreover, as the planetary motion is often known from radial velocity campaigns, it is possible to stack the observed signature in the planet rest frame with high precision. For hot Jupiters, an offset between the expected line positions and the measured line positions can be detected and attributed to wind patterns in the exoplanet atmosphere (e.g., Snellen et al. 2010; Wyttenbach et al. 2015; Brogi et al. 2016; Allart et al. 2018; Ehrenreich et al. 2020). Therefore, high-resolution datasets provide key information on atmospheric dynamics. Finally, as the lines are resolved and well sampled, the line cores probe higher in the atmosphere and they can be used to measure the change of temperature with altitude in the atmosphere (e.g., Wyttenbach et al. 2015; Seidel et al. 2020).

The first keystone in the detection of exoplanet atmospheres at high spectral resolution was done at infrared wavelength using the CRIRES instrument (Snellen et al. 2010). The second keystone was the use of the HARPS spectrograph to detect and resolve the sodium doublet of HD189733b (Wyttenbach et al. 2015). HARPS is a stable fiber-fed visible high-resolution spectrograph installed on the 3.6m ESO telescope at LaSilla. Since 2015, tens of studies using stable high-resolution spectrographs, both at visible and near-infrared wavelengths, installed on medium class telescope revolutionized the exoplanet atmospheric field. Among them, the first detection of metastable helium linking the thermosphere to the exosphere (Allart et al. 2018, Nortmann et al. 2018), of metals exhibiting the peculiar chemistry of ultra-hot Jupiters (Hoejmakers et al. 2018), of condensation at the terminator providing an access to the 3D structure of exoplanets (Ehrenreich 2020) or even the multiple detections of molecules providing a robust understanding of the atmospheric chemistry (Pelletier et al. 2021).

At the end of 2021, the Near-InfraRed Planet Searcher (NIRPS) will join HARPS on the 3.6m ESO telescope at LaSilla. NIRPS is an ultra-stable fiber-fed near-infrared (0.98-1.8 microns) high-resolution spectrograph that can work simultaneously or not to HARPS. The NIRPS consortium was granted by ESO of 720 nights in exchange for the instrument. A third of this time is foreseen to study the exoplanet atmosphere. In this talk, I will describe how we aim at splitting this unparalleled allocation including a transit survey of 100 exoplanets, an emission survey of 40 exoplanets, and in-depth studies of few key systems in transmission.

NIRPS will excel by detecting and retrieving multiple molecules (H₂O, CH₄, O₂, CO) providing crucial information on the presence of clouds, C/O ratio, and thus on the formation of exoplanets. Moreover, NIRPS has access to the helium triplet providing crucial constraints of the dynamic and physical processes at play in the upper atmosphere and even in the exosphere. Finally, NIRPS has the unique opportunity to do all of this simultaneously and is the sole instrument in the southern hemisphere to do it.

The simultaneous observations of HARPS will complement the NIRPS observations by studying the presence of metals in the hottest Jupiter-like exoplanet but also by studying multiple atmospheric tracers such as the Na doublet, the Li, or H-alpha line. Finally, both HARPS and NIRPS will deliver precise radial velocity that can be used to constrain the orbital architecture through the Rossiter McLaughlin effect.

By the end of its guarantee time observations, the NIRPS consortium will be able to draw statistical conclusions that could help explain how exoplanets formed and evolved, why the evaporation desert exists, what are the interactions between stars and planets, what is the composition of exoplanet atmospheres, what are the properties of clouds and hazes and what is the dynamics of exoplanet atmospheres.

References:

Allart, R., Bourrier, V., Lovis, C., et al. 2018, Science, 362, 1384

Brogi, M., de Kok, R. J., Albrecht, S., et al. 2016, The Astrophysical Journal, 817, 106

Ehrenreich, D., Lovis, C., Allart, R., et al. 2020, Nature, 580, 597

Hoeijmakers, H. J., Ehrenreich, D., Heng, K., et al. 2018, Nature, 560, 453

Nortmann, L., Pallé, E., Salz, M., et al. 2018, Science, 362, 1388

Pelletier, S., Benneke, B., Darveau-Bernier, A., et al. 2021 accepted in AJ, arXiv:2105.10513

Seidel, J. V., Ehrenreich, D., Pino, L., et al. 2020b, Astronomy and Astrophysics, 633, A86

Snellen, I. A. G., de Kok, R. J., de Mooij, E. J. W., & Albrecht, S. 2010, Nature, 465, 1049

Wyttenbach, A., Ehrenreich, D., Lovis, C., Udry, S., & Pepe, F. 2015, Astronomy and Astrophysics, 577, A62

How to cite: Allart, R. and the The NIRPS consortium: Atmospheric characterization by combining HARPS and NIRPS, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-437, https://doi.org/10.5194/epsc2021-437, 2021.

In the last decade, laser frequency combs (LFCs) have been established as the ideal wavelength calibration source for high-resolution, high-precision astronomical spectroscopy. LFCs provide a dense train of equally spaced and extremely narrow lines which frequencies are directly linked to the fundamental time reference of the SI second. This – at least in principle – allows to derive wavelength solutions orders of magnitude more precise and accurate than possible with conventional calibration schemes, essential in particular within the context of radial velocity studies of exoplanets and the hunt for habitable planets around solar-type stars. In addition, the great number and narrow width of LFC lines allows a precise characterization of astronomical spectrographs, e.g. of the line-spread function, relevant for atmospheric characterization by transit spectroscopy. Also, LFCs are the only type of calibration source that can provide the extreme accuracy needed for tests of fundamental physics on cosmological scales, e.g. the variation of the fine-structure constant or the direct observation of the expansion of the Universe (Sandage test). Therefore, future high-resolution spectrographs like ELT/HIRES will rely entirely, or at least predominantly, on LFCs for wavelength calibration. 

However, the LFCs currently in operation with e.g. HARPS or Espresso do not cover the blue spectral range. They only provide flux to slightly bluewards of 500nm. This leaves a very significant part of the spectrographs spectral range (e.g. 43% for Espresso) without LFC coverage and does not permit the LFC to be used as primary wavelength reference. The reason behind this is that suitable laser gain media are all located in the near-IR and 'spectral broadening' by non-linear optical effects is necessary to bring the light into the visible domain. Therefore, covering the blue and near-UV range of the spectrum with astronomical LFCs is an intrinsically hard problem that has so far not been mastered in practice. 

To overcome this issue, BLUVES (BLue to UV Extreme precision astronomical Spectroscopy) is an interdisciplinary collaboration between the Observatory of Geneva, the Swiss Center for Electronics and Microtechnology (CSEM), the Deutsches Elektronen-Synchrotron (DESY), ESO and others with the aim of developing a laser frequency comb covering the blue and near-UV spectral range down to the atmospheric cut-off at 350nm. 

To achieve this challenging goal, a set of novel and innovative technologies have to be developed over the next years. 
One key aspects here is the use of an electro-optic modulation comb which can directly produce the large required line separation of 15 to 20GHz without the need for mode-filtering in Fabry-Perot cavities (E. Obrzud et al. 2018). 
Even more important will be the approach for harmonic driven supercontinuum generation. This will involve the development of an integrated optical chip containing a lithium-niobate waveguide that facilitates second- and third-harmonic generation as well as spectral broadening (E. Obrzud et al. 2019).

In parallel to this, we are investigating novel wavelength-calibration methods and algorithms needed to actually make use of the precision and accuracy provided by the LFC. A careful study of the Espresso wavelength solution revealed multiple types of systematics that had not been seen before (T. Schmidt et al. 2021). Pushing to higher accuracy and precision will unavoidably require improved techniques to eliminate or correct for the observed effects. This does not only involve new software but also requires a tunable LFC to accurately characterize the instrument properties in detail, which again highlights the importance of an LFC system that covers the full spectral range of the spectrograph.

We will present the current status of the BLUVES project, its key aspects and the expected development over the next years.

How to cite: Schmidt, T., Bouchy, F., Brasch, V., Herr, T., Pepe, F., and Lovis, C.: BLUVES: A Blue Laser Frequency Comb for VLT/Espresso, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-323, https://doi.org/10.5194/epsc2021-323, 2021.

SPHERE, the high contrast imaging facility at the VLT has contributed significantly to the exploration of planetary systems, by revealing many details in proto-planetary and debris disks, by measuring the atmospheric properties of young giant planets and by deriving constraints on the giant planet population in long orbital periods. Such achievements allow us to provide a better understanding of planetary formation and evolution. The versatility of SPHERE also enables various secondary and sometimes unexpected science cases owing to a large spectral coverage from the visible to the near IR, and the availability of several observing modes as imaging, spectroscopy and polarimetry. Yet the access to the region where planets are expected to form, is not complete and still represents a challenge. To overcome this limitation larger contrasts at shorter separations are definitely required. 

The SPHERE+ concept precisely aims to provide the capabilities to primarily access the bulk of the young giant planet population down to the snowline  in order to bridge the gap with complementary techniques. As a second objective, SPHERE+ should be able to observe an increased sample of targets, fainter and redder than those observed in the first survey. Finally, SPHERE+ will provide a higher level of characterization of planet’s atmospheres. To achieve these goals, SPHERE should be upgraded with a faster Adaptive Optics system to reach  high contrasts at closer angular separations, together with a more sensitive wavefront sensor in the infrared to observe redder targets. Medium and high spectral resolution in the near infrared will be brought by a dedicated IFU spectrograph or taking advantage of the HiRISE project to combined SPHERE and CRIRES+. We will present the science cases and the technical solutions that are foreseen to reach the appropriate performances, and provide potential ways for such an upgrade.  

How to cite: Boccaletti, A. and the SPHERE+ consortium: SPHERE+, Imaging young planets down to the snow line, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-24, https://doi.org/10.5194/epsc2021-24, 2021.

Direct imaging is a powerful exoplanet discovery technique that is complimentary to other techniques with great promise in the era of 30-meter class telescopes. Space-based transit surveys have revolutionized our understanding of the frequency of planets at small orbital radii around sun-like stars. The next generation of extremely large ground-based telescopes will have the angular resolution and sensitivity to directly image planets with R < 4 Earth radii around the very nearest stars. Here we predict yields from a direct imaging survey of a volume-limited sample of sun-like stars with the Mid-Infrared ELT Imager and Spectrograph (METIS) instrument, planned for the 39-m European Southern Observatory (ESO) Extremely Large Telescope (ELT) that is expected to be operational towards the end of the decade. Using Kepler occurrence rates, a sample of stars with spectral types A-K within 6.5 pc, and simulated contrast curves based on an advanced model of what is achievable from coronagraphic imaging with adaptive optics, we estimate the expected yield from METIS using Monte Carlo simulations. We find the METIS expected yield of small planets in the N2 band (10.10 - 12.40 μm) is 1.15 planets which is greater than similar observations in the L (3.70 - 3.95 μm) and M (4.70 - 4.90 μm) bands. We also determine a 42% chance of detecting at least one Jovian planet in the background limited regime assuming a 1-hour integration. We calculate the yield per star and estimate optimal observing revisit times to increase the yield. We also analyze this survey if performed in the northern hemisphere and find there are additional targets worth considering. Finally, we present an observing strategy in order to maximize the possible yield for limited telescope time, resulting in 1.52 expected planets in the N2 band.

How to cite: Bowens, R., Meyer, M., Delacroix, C., Absil, O., van Boekel, R., Quanz, S., Shinde, M., Kenworthy, M., Carlomagno, B., Orban de Xivry, G., Cantalloube, F., and Pathak, P.: Exoplanets with ELT-METIS I: Estimating the Direct Imaging Exoplanet Yield Around Nearby Stars within 6.5 Parsecs, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-79, https://doi.org/10.5194/epsc2021-79, 2021.

Combining high-contrast imaging with medium-resolution spectroscopy has recently been shown to significantly boost the direct detection of exoplanets. In this optic, HARMONI, one of the first-light instruments to be mounted on ESO's ELT, will be equipped with a single-conjugated adaptive optics system to reach the diffraction limit of the ELT in H and K bands, a high-contrast module dedicated to exoplanet imaging, and a medium-resolution (up to R = 17 000) optical and near-infrared integral field spectrograph. When combined, these systems will provide unprecedented contrast limits at separations between 50 and 400 mas. We will present in this talk the results of extensive simulations of exoplanet observations with the HARMONI high-contrast module. We used an end-to-end model of the instrument to simulate observations based on realistic observing scenarios and conditions. We then analyzed these observations with the so-called "molecule mapping" technique, which has shown in recent studies its efficiency to disentangle planetary companions from their host star and boost their signal. Although HARMONI has not been fully designed for high-contrast imaging, we will show that it should greatly outperform the current dedicated instruments, such as SPHERE on the VLT. We detect planets above 5σ in 2 hours at contrasts up to 16 mag and separations down to 75 mas in several spectral configurations of the instrument. Simulating planets from population synthesis models, we could image in this amount of time companions as close as 1 AU from a host star at 30 pc and as light as 2 M_Jup. We show that taking advantage of the combination of high-contrast imaging and medium-resolution spectroscopy through molecule mapping allows us to access much fainter planets (up to 2.5 mag) than the standard high-contrast imaging techniques. We also demonstrate that HARMONI should be available for near-critical exoplanet observations with this method during 60 to 70% of telescope time at the ELT.

How to cite: Houllé, M., Vigan, A., Carlotti, A., Choquet, É., Cantalloube, F., Phillips, M. W., Sauvage, J.-F., Schwartz, N., Otten, G. P. P. L., Baraffe, I., Emsenhuber, A., and Mordasini, C.: Direct imaging and spectroscopy of exoplanets with the ELT/HARMONI high-contrast module, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-817, https://doi.org/10.5194/epsc2021-817, 2021.

Multilayer optical coatings are widely used on the surface of optical components to enhance the transmittance of light in certain spectral regions while reducing it in other regions. Discrepancies between the measured and predicted spectral performance of optical components with such coatings can primarily be attributed to deposition errors and uncertainties in the refractive indices of the materials used for these coatings. Our simulation uses two-dimensional transmission line modelling to evaluate the transmittance of light at a given angle of incidence through multilayer coatings deposited on a substrate material. We perform a number of Monte Carlo simulations to obtain statistical information about the tolerance of the coating performance to systematic and random uncertainties in deposition thickness, refractive index and operating temperature. We present the posterior distributions of the deviations from the nominal performance that result from the propagation of each of these uncertainties for a number of hypothetical scenarios. We find that these uncertainties have the potential to cause significant differences between the designed and achieved performance. Our results indicate that the sensitivity of each layer to the various sources of uncertainties can vary on a case-by-case basis. With the aid of accurate manufacturing recipes and uncertainty amplitudes from commercial manufacturers, this simulation can provide a proficient tool to predict variations in the performance of multilayer optical coatings used in exoplanet spectroscopy.

How to cite: Thurairethinam, V. and Savini, G.: Monte Carlo transmission line modelling of multilayer optical coatings for performance sensitivity of exoplanet spectroscopy, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-716, https://doi.org/10.5194/epsc2021-716, 2021.