Constraining the Atmosphere and Interior of the Directly Imaged Planet AF Leporis b with VLTI/GRAVITY

The next era of giant planet characterization will be defined by studying planets discovered with Gaia and directly detected with interferometry. The formation history and interior structure of known directly imaged giant planets is uncertain, but dynamical masses from absolute astrometry constrain bulk and atmospheric properties. I will present novel VLTI/GRAVITY observations of AF Leporis b, the lowest mass imaged with a dynamical mass. I will reveal our spectrum showing an unambiguous methane detection, which constrains the C/O ratio and metallicity of the atmosphere. I will detail our analysis of the atmosphere, leveraging the dynamical mass, to constrain the temperature structure and luminosity of the planet. I will present the first constraint on the interior structure (bulk metallicity and core to envelope fraction) of a directly imaged planet, setting the stage for assessing core accretion formation of directly detectable giant planets in the era of Gaia and GRAVITY.