New ultracool dwarfs in Gaia DR2
Creators: name: Reylé Céline
Publisher: name: Zenodo
Year: 2019
Subjects: stars: low-mass
solar neighborhood
Galaxy: stellar content
surveys
catalogs

description: Detailed population studies of ultracool dwarfs are persistently plagued by incompleteness. While hundreds of VLM dwarfs have been uncovered in red and infrared sky surveys, this population remains incomplete, even in the solar neighborhood, due to their faint magnitudes. The Gaia mission has provided the means to uncover nearby VLM dwarfs through astrometric, rather than purely photometric, selection. This holds the promise of a truly volume-complete sample. Such a well-characterized and complete volume-limited sample will provide space density, luminosity, and mass functions free of biases contrarily to previous determinations. This is essential to put constraints on stellar and substellar formation theories.

We will present a study of the content of Gaia DR2 at the low-mass end. We will first investigate the known sample of late M, L, T and Y dwarfs retrieved in Gaia DR2, and compare it with the up-to-date BT-Settl atmosphere models. We will next show that thousands of new candidates are revealed by Gaia DR2. They are evenly distributed across the sky, filling in “missing” populations in the Southern hemisphere and Galactic plane. Over 160 candidates have measured distances of less than 30 parsec, showing that even the nearby census is not complete.
description: Contributed talk at the 53rd ESLAB symposium: the Gaia Universe.
Associated publication: Reylé, C. 2018, A&amp;A, 619, L8, doi: 10.1051/0004-6361/201834082
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