Hundreds of planetary systems are currently known. A deep understanding of the architecture of both RV-detected systems and transit-detected systems is essential to probe planetary system formation.

In this session we address the question of the formation, dynamical evolution and stability of planetary systems in a broad sense, including the effects of planet-disc interactions, resonances, high eccentricity migration, binary stars, chaotic dynamics,...

The spatially resolved characterization of planet-forming disks carried out over the last decade suggests that massive planets form very soon after a star is born. Nonetheless, newly born planets remain very elusive and up to date, we only have one confirmed young exoplanet system embedded in the natal disk.

On the one hand, the census of planet-forming disks depicted by ALMA revealed a number of substructures that are ascribed to the disk interaction with forming planets. The exquisite data quality achieved by some datasets even enabled the prediction of the mass and location of the putative planets. On the other hand, the most promising technique aimed at detecting such planets, that is the direct imaging in the near-infrared, has so far yielded limited results.

In this session, we bring together experts from different disciplines of the planet formation in order to review what are the reasons to believe (or not) that planets embedded in disks are common but elusive as well as what is the best strategy to reveal their existence in the near future.

Atmospheric aerosols and cloud particles are found in every atmosphere of the solar system, as well as, in exoplanets. Depending on their size, shape, chemical composition, latent heat, and distribution, their effect on the radiation budget varies drastically and is difficult to predict. When organic, aerosols also carry a strong prebiotic interest reinforced by the presence of heavy atoms such as nitrogen, oxygen or sulfur.

The aim of the session is to gather presentations on these complex objects for both terrestrial and giant planet atmospheres, including the special cases of Titan’s, Pluto's and Triton's hazy atmospheres. All research aspects from their production and evolution processes, their observation/detection, to their fate and atmospheric impact are welcomed, including laboratory investigations and modeling.

Planetary accretion, giant collisions, core formation, magma-ocean crystallization, catastrophic ougassing and other important processes during the early days of planet formation set the stage for the long-term evolution of terrestrial planets and their surface habitability. These early processes can happen simultaneously or in recurring stages, and are ultimately followed by progressive melting and outgassing processes, long-term mantle mixing/differentiation, core-mantle interaction, as well as inner-core crystallization.
In addition, atmosphere characterisation of rocky exoplanets is becoming a reality thanks to emerging advanced space and ground-based observatories. Mass-radius measurements and observations of stellar spectra suggest that rocky exoplanets exhibit considerable chemical and physical diversity relative to the rocky planets of the Solar System.
In order to better characterise and interpret this diversity, we invite a wide range of abstracts focusing on the formation and evolution of terrestrial bodies, the potential of a planet to become habitable, but also observations and retrievals of exoplanetary atmospheres, modelling of atmospheric composition and structure, photochemistry, radiative transfer, magma ocean/interior-atmosphere coupling and geochemical cycling in rocky exoplanets. We also welcome studies on planetary habitability and studies that use Earth and Solar System telluric bodies as analogues to investigate planetary diversity.

A star and its surrounding planets are born from the same molecular cloud, meaning they share a common origin. However, compositional deviations of (particularly rocky) planets from stars are commonplace, and may occur by gas-dust fractionation in the protoplanetary disk and/or over the course of their subsequent dynamical evolution. Using our Solar System as an example, the Earth and the other terrestrial planets are known to be depleted with respect to the Sun in atmosphere-forming elements (H, C, N and O). This depletion also extends, to a lesser degree, to rock-forming elements such as Mg and Si. Observations of polluted white dwarf atmospheres suggest that such a volatile depletion process – i.e. devolatilization – may also take place in rocky exoplanetary materials. However, the mechanisms that lead to devolatilization are yet to be fully understood and are not considered in most (if not all) existing planet formation models.

This session welcomes submissions focusing on either nebular (e.g. dust formation, condensation, and evaporation/sublimation) or post-nebular (e.g. energetic accretion and impacts, hydrodynamic escape, and photoevaporation) processes that may lead to devolatilization in rocky (exo-)planets. Submissions about planet formation models that consider any devolatilization processes are particularly encouraged. Observations and simulations of polluted white dwarf atmospheres and of the properties of rocky exoplanets, for example by reflection/emission spectroscopy, are also invited.

We hope to develop synergies between cosmochemistry, astrochemistry, planet formation dynamics, and exoplanet observations for developing quantitative predictions for the elemental composition of rocky exoplanets. Such information is crucial, together with the current exoplanet observables (i.e. mass, radius and orbital properties), to constrain rocky exoplanetary interiors, surfaces, and atmospheres. Eventually, these will lead to a new level of predictive statistical understanding of the detailed properties of rocky exoplanets in the solar neighbourhood, guiding the future exoplanet-dedicated missions or mission concepts, such as, PLATO, Ariel, HabEx, LUVOIR, and LIFE.

The field of extrasolar planets is one of the most rapidly changing areas of astrophysics and planetary science. Ground-based surveys and dedicated space missions will have soon discovered 5000 planets with many more detections expected in the near future. A key challenge is now the characterisation of their atmospheres in order to answer to the questions: what are the properties of these worlds and what processes govern their formation and evolution?

To answer these questions, a broad range of skills and expertise are required, stretching from Solar System science to statistical astrophysics, from ground-based observations to spacecraft measurements, and atmospheric/interior/orbital modelling. The numerous studies conducted in the past twenty years have unveiled a large diversity of atmospheres, from ultra-hot Jupiters to temperate super-Earths.
Current as well as future ground and space based facilities (e.g. ESPRESSO, E-ELT, JWST, ARIEL, ...) will characterise this multifarious population in stunning detail and challenge our current understanding. Both theoretical works and experimental measurements are required to prepare for such a change of scale.

This session will focus on the atmospheric characterisation of exoplanets and the conveners welcome any abstract related to this subject.

Exoplanets are being discovered in large numbers thanks to recent and ongoing surveys using state-of-the-art instrumentation from the ground and from space. In the next years, new astronomical instruments will further scout our Galaxy to overcome the current observational biases in the search of alien worlds, to gain a deeper understanding of the chemical and physical properties of both exoplanets and their environments, and to unveil the processes of formation and evolution of planets and their atmospheres.

The goal of this session is to bring together the instrumentation and observational communities that are underpinning the future of this field. Contributions are invited to review ongoing programmes of exoplanet and circumstellar discs discovery and characterisation, to update on the progress of planned instrumentation programmes, and to present innovative ideas for future instrumentation.

Next-generation missions such as JWST (Webb), Ariel, ELT and PLATO will characterise the atmospheres of exoplanets. The thermal and chemical structure of the upper atmospheres of exoplanets are affected by high-energy phenomena such as stellar X-rays, UV photons, flares, coronal mass ejections (CMEs) and energetic particles. The aim of this session is to understand the impact of high-energy phenomena on exoplanet atmospheres and the expected observable signatures from these phenomena.

HST and ground-based spectrograph observations have shown that continuous stellar high-energy radiation leaves an imprint in Lyman-alpha, H-alpha and helium transits. These signatures are also observed for heavier elements such as oxygen and ionized carbon. These observable signatures are expected to vary with stellar age and spectral type. X-rays and UV photons can affect atmospheric evolution over the planet's lifetime. At the same time, energetic particles from the star and the Galaxy can affect atmospheric chemistry that may be observable using transmission spectroscopy with Webb.

TESS and Kepler have provided vital information about flare energies and frequencies for Sun-like and M dwarfs, which is incorporated into chemical modelling of exoplanet atmospheres. Models of star-planet interaction have found that transient high-energy events, such as flares and CMEs, can enhance, or alter, transit signatures. Moreover, these models predict X-ray emission from the shocks of interacting stellar winds and exoplanet atmospheres. Finally, current theoretical models show that exoplanetary magnetic fields play an enormous role in transit signatures. The complexity and methodology used for these models vary greatly and affect predicted atmospheric mass-loss rates and transit signatures by orders of magnitudes. More detailed observations with future missions are important to constrain the impact of transient high-energy events and magnetic fields on these observations.

This session will focus on observations and modelling efforts relating to high-energy phenomena and exoplanet atmospheres and the conveners welcome any abstract related to this subject.

Almost 5000 exoplanets are now confirmed, a number rising almost daily. This impressive rate of discoveries, impulsed by the synergies between different observational techniques and space-based missions, reveals a great variety of planets and planetary systems that challenge our understanding of planetary occurrences, physical-chemistry properties, and system architectures. Since each technique and method provide only a part of the bigger picture, the confluence of different perspectives is a must.
Hence, in this session, we aim to bring together recent results and studies performed by observers, modelers, and experimentalists, and a combination of them to open discussions about the pathways that the community needs to follow to understand the exoplanetary variety fully and promote and inspire the collaboration between teams with different expertise. In particular, this session welcomes any abstract related to the following topics:

(1) groundbreaking discoveries of planets and systems of special interest (due to peculiar physical properties/orbital architectures, amenable targets for atmospheric investigations, etc.)
(2) cutting edge measurements of exoplanet properties (tidal distortions, spin rates and angles) and first tentative detections of satellite or rings;
(3) deep characterization of planetary systems and their global picture (precise measurements of radii, masses and internal planetary compositions, observed/theoretical populations, occurrences, etc.);
(4) synergies between different techniques for comprehensive exoplanet characterization (photometry, spectroscopy, radial velocities, transit timing variations, radio observations, etc.);
(5) hunting surveys from the ground- and/or space-based observatories in the search for new planets and systems.

Astrobiology is the study of whether present or past life exists elsewhere in the universe. To understand how life can begin in space, it is essential to know what organic compounds were likely available, and how they interacted with the planetary environment. This session seeks papers that offer existing/novel theoretical models or computational works that address the chemical and environmental conditions relevant to astrobiology on terrestrial planets/moons or ocean worlds, along with other theoretical, experimental, and observational works related to the emergence and development of Life in the Universe. This includes work related to prebiotic chemistry, the chemistry of early life, the biogeochemistry of life’s interaction with its environment, chemistry associated with biosignatures and their false positives, and chemistry pertinent to conditions that could possibly harbor life (e.g. Titan, Enceladus, Europa, TRAPPIST-1, habitable exoplanets, etc.). Understanding how the planetary environment has influenced the evolution of life and how biological processes have changed the environment is an essential part of any study of the origin and search for signs of life. Earth analogues experiments/instruments test and/or simulation campaigns and limits of life studies are included as well as one of the main topics of this session. Major Space Agencies identified planetary habitability and the search for evidence of life as a key component of their scientific missions in the next two decades. The development of instrumentation and technology to support the search for complex organic molecules/sings of life/biosignatures and the endurance of life in space environments is critical to define unambiguous approaches to life detection over a broad range of planetary environments.

Our search for life on our neighboring planets and moons is guided by increasing our knowledge on terrestrial life’s survivability and adaptability and on our capacity to detect its traces. On one hand, extremophilic organisms of all domains of life have shown us extraordinary adaptations strategies in colonizing Earth’s most inhospitable environments and their study has far reaching implications not only for astrobiology research but also in different fields such as ecology, molecular and cellular biology, physiology, and biotechnology. On the other hand, each planetary target presents unique environments and conditions that could enhance or decrease biosignatures’ preservation and therefore their detectability by in situ, sample return, or remote measurements. Studies from field analogs, laboratory, simulation and space experiments or theoretical investigations can greatly support and guide current and future missions dedicated to search for life and its traces. Experiments on space platforms and missions, for instance, allow the exposure of biological and chemical samples to unique outer space conditions but require special hardware developments of high interest for astrobiology and related fields.