Unlocking the Secrets of our Coolest Neighbours: Distances and Atmospheres of the Y Brown Dwarf Population

Clémence Fontanive ( Université de Montréal )

Y brown dwarfs are extremely cold objects floating freely through space, with masses of few times that of Jupiter and similar temperatures to cold gas giants. The similarities they share with giant planets around stars make them excellent proxies to study the atmospheres of extra-solar planets, although their origins and properties remain poorly understood. Using a new method combining HST observations and Gaia, I am measuring highly-precise distances for these objects, which enables robust constraints on their demographics in space, offering unprecedented insights into their formation. Together with homogeneous sets of near-infrared fluxes, this allows me to perform crucial investigations of atmospheric characteristics for the coldest objects around us, from which I will obtain important new constraints for theoretical models at the lowest masses and temperatures.