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More than 5000 exoplanets have been discovered to date, yet the formation and early evolution of gas giant planets remains an unsolved puzzle. Taking advantage of the contrast gain obtained by combining adaptive optics with interferometric observations, we present a VLTI/GRAVITY survey of young, directly imaged gas giant planets to unveil their formation history. The observations provide astrometric data of unprecedented accuracy, being crucial for refining the planets' orbital parameters and illuminating their dynamical histories. Repetitive observations of the exoplanets at medium spectral resolution (R ~ 500) provide a catalogue of K-band for a number of our targets, revealing molecular signatures from e.g., CO, H2O, CH4, and CO2. With the help of self-consistent atmosphere models and atmospheric retrievals, the physical parameters and the C/O ratio of the planets can be constrained, kick-starting the difficult process of linking planetary formation with measured atomic abundances. In the near future, the GRAVITY+ upgrade will enable the observation of even fainter and closer-in exoplanets.
Kammerer et al. (Wed,) studied this question.