Federico Marocco (Caltech/IPAC): "The Substellar Neighborhood: A Stunningly Diverse Population of Brown Dwarfs within 20pc of the Sun"

Title: The Substellar Neighborhood: A Stunningly Diverse Population of Brown Dwarfs within 20pc of the Sun

Abstract: The census of the coldest constituents of the Solar Neighborhood, here defined as a 20pc-radius sphere around the Solar System, remains incomplete. Completing such census is one of the driving goals for the CatWISE and "Backyard Worlds: Planet Nine" teams, who have discovered hundreds of new nearby late-T and Y dwarfs using data from WISE/NEOWISE. In this talk I will present the results of a multi-telescope observing campaign to characterize some of these new discoveries. Photometric and astrometric follow-up is revealing a stunning diversity among the substellar population, a diversity that recent atmospheric models suggest is driven by metallicity. I will also highlight a handful of the most intriguing discoveries -- the first Y-type subdwarf, a.k.a. "The Accident"; CWISE J1935-1546 and CWISE J1446-2317, two of the coldest brown dwarfs ever observed; and Ross 19B, one of the lowest-mass, coldest substellar companions to a main-sequence star.