Combing the brown dwarf desert with Gaia DR3

Abstract

We have created an up-to-date catalogue of 214 brown dwarfs (BDs) in binaries with P < 10 4 d. This allows us to examine the population statistics of the BD desert. We searched Gaia third data release (DR3) non-single star (NSS) results for orbital inclinations of BD candidates, deriving 12 new masses. Three remain as desert BDs whereas nine candidates are found to be low-mass stars. We impro v ed the radial velocity (RV) solutions for three previously studied BD candidates. A further 19 BD masses with periods less than ∼1200 d were identified in the DR3 binary masses data base. We confirm a valley in the mass distribution with a minimum around 30-35 M jup, and find that periods < 100 d are still underpopulated in comparison with longer periods. The updated mass and eccentricity distribution of BDs still shows a marginally statistically significant split into high- and low-mass BD populations. This hints at two different parent distributions, and two potential origins -either akin to planetary formation, or stellar. There are no low-eccentricity BDs at periods around 100 d. The mass-metallicity distribution of BDs indicates that core accretion is not the dominant formation mechanism for BDs as they do not follow the same trends that giant exoplanets do with metallicity. We identify a diagonal envelope bounding the Gaia BDs in the mass-period plane due to the detection thresholds of the currently available NSS solutions from 34 months of data.