Abstract
Probing the cloud properties of a benchmark variable T dwarf
Etienne Artigau (Université de Montréal/iREx)
SIMP0136 is one of the nearest isolated brown dwarfs to the Sun; this early-T dwarf lies in the temperature range where dust-bearing clouds, more typical of L dwarfs, sink below the photosphere. The inhomogeneous cloud coverage on its surface leads to rotation-induced variability at the 2-7% level over its 2.4 h rotation. Furthermore, the evolution of the cloud patterns leads to a modulation of the lightcurve over timescales of a few days. We propose GTO observations to obtain time-resolved SOSS spectroscopy of this benchmark variable brown dwarf over different rotations periods. These observations will detect variability at the 20-70 level for all resolution elements within a 10-min time bin. By probing different heights in the atmosphere, variability of di erent chemical species will trace the vertical extent of dust-clouds. Detection of out-of-equilibrium species, such as Cs, will provide insight into upwelling mechanisms in ultracool atmospheres. This work will have a strong bearing on the study of hot exoplanets; at a temperature of 1200 K, SIMP0136 is similar to numerous hot Jupiters. Proper description of dust behaviour is key in understanding transit spectroscopy data as dust clouds can readily mask the lower layers of an otherwise clear atmosphere.
Mode of presentation: poster