Although thousands of brown dwarfs and extrasolar planets have been discovered up to date, their formation and evolution models remains unknown. Hence, it is necessary to identify these objects in a wider range of effective temperature, gravity and metallicity to understand them. The main scientific objective of our project is to identify and characterise brown dwarfs and exoplanets with complementary techniques such as transit, radial velocity, and direct imaging to constrain models of formation and evolution.

In a first approach, we plan to detect a large number of ultracool dwarfs (UCDs) at different effective temperatures, ages and metallicities. The diversity in physical properties of UCDs provides a natural link between the very low-mass stars and giant planets. The study of UCDs provides constraints to the stellar and planet formation models and is a testbed for very cool atmospheric models. The study of their physical properties and atmospheric composition will serve as benchmarks to characterise exoplanet atmospheres. The Euclid survey will detect a huge number of UCDs, including the coolest and the nearest, and dozens of young and metal poor substellar companions. The determination of their dynamical masses will allow us to test theoretical evolutionary models. In a second approach, we plan to investigate the timescales of planet formation and constrain dynamical models of planet evolution, by performing a search for transiting exoplanets around young nearby stars using the TESS light curves. The advent of the Gaia mission will allow us to revise the census of members in open clusters, star- forming regions, and young moving groups to investigate their spatial distributions and kinematics. Clusters and young moving groups are ideal to investigate the stellar and substellar evolution because their members share the same distance, age, and metallicity.

In tight collaboration with the other nodes involved in this project, the IAC will focus on five particular objectives to better understand the similarities and differences between the substellar and planetary populations:

(1) Preparation and first light exploitation of the data from the Euclid mission on UCDs: multiplicity and detection of the coolest and nearest objects in the deepest (VIS, YJH ~ 24 mag AB) and widest survey (15000 square degrees) ever conducted from space with an unprecedented sensitivity, stability, and image quality. Our group is part of one of the two Independent Legacy Survey groups appointed by ESA with immediate access to the data.

(2) Determination of the dynamical masses of the substellar companions in a wide range of ages using complementary techniques (direct imaging, space missions and ground-based adaptive optic systems).
(3) Search for gaseous and rocky planets by transit and radial velocity techniques around members of young moving groups, open clusters, and star-forming regions to constrain dynamical models of stellar and planet formation.

(4) Investigate the spatial distribution and dynamics of the nearest (<= 500 pc) and youngest (<= 1 Gyr) clusters, star-forming regions, and young moving groups exploiting data from Gaia with Bayesian techniques complemented by deeper photometric surveys to reach the end of the initial mass function.
(5) Determination of the properties of substellar subdwarfs (isolated and as companions) and the halo mass function using current large scale surveys, such as Euclid, and adaptive optic systems.