Wednesday, June 11 - Plenary Session

Name:  Michael Line

Affiliation:  UCSC

Title:  Determination of Temperatures and Abundances in Brown Dwarf Atmospheres

Brown dwarf spectra contain a wealth of information about the temperature structure and molecular abundances. The standard approach to interpreting brown dwarf spectra has been through the use of self-consistent stellar grid models that attempt to fit basic stellar parameters such as the effective temperature and surface gravity and occasionally eddy diffusivity. We present a novel inverse approach based upon earth and solar system atmosphere remote sensing techniques to determine the detailed temperature profile, molecular gas abundances, surface gravity, and photometric radius (if distance is known) free from many of the underlying assumptions present in current grid-modeling. We apply our inverse approach to well studied cloud-free benchmark brown dwarf spectra (like Gl570D) and present retrieved abundances for H2O, CH4, CO, CO2, and NH3. From these abundance determinations it is possible to address the importance of vertical mixing as well as a determination of the elemental C/O ratio, which is indicative of the formation environment. Time permitting we will also present preliminary retrieval results on the high-resolution spectrum of Luhman 16A.