Fundamental Atmospheric Properties of Ultra Cool Brown Dwarfs
Abstract
Brown dwarfs occupy a unique realm between planets and stars. They are excellent laboratories for investigating the physics and chemistry of jovian-like worlds in the 200-2800K range as well as the transition from the stellar-to-planetary realms. The spectra of brown dwarfs are key to exploring the chemistry and physics that takes place in their atmospheres. Late T-dwarf (Teff<1000K) spectra are particularly diagnostic due to their relatively cloud free atmospheres and deep molecular bands. Combined with the use of powerful atmospheric retrieval tools, late T-dwarf spectra enable relatively precise constraints on the molecular/atomic abundances. Constraints on these properties can be used to derive the elemental abundances (metallicity, C/O), presence of chemical disequilibrium, and non-radiative-convective equilibrium temperature perturbations. Here we present an update to a long term program aimed at characterizing the fundamental atmospheric properties of brown dwarfs, starting with the late T-dwarfs. Specifically, we will present key chemical trends in H2O, CH4, NH3, Na, and K and elemental abundance ratios derived from ~60 late T and Y-dwarfs (400 - 900K) IRTF SpeX and HST WFC3 (more than triple past published works). We will also explore prospects for ultra-cool dwarf abundance determinations with the James Webb Space Telescope.
- Publication:
-
American Astronomical Society Meeting Abstracts #235
- Pub Date:
- January 2020
- Bibcode:
- 2020AAS...23527401L