Spitzer Space Telescope - General Observer Proposal #20544


Metallicity and Gravity Diagnostics in the Coldest Brown Dwarf Spectra

Principal Investigator: Adam Burgasser
           Institution: Massachusetts Institute of Technology

Co-Investigators: 
J. Davy Kirkpatrick, IPAC/Caltech                                     
Chris Tinney, AAO                                                     
Adam Burrows, University of Arizona                                   

Science Category: brown dwarfs/very low mass stars 
 Observing Modes: IracMap IrsStare 
  Hours Approved: 20.7 

Abstract:
Brown dwarf spectra are rich in diagnostics of temperature, gravity
and metallicity.  However, in the coldest sources, these parameters
can be entangled with competing effects for a few major absorbers.  We
have identified three late-type T dwarfs that exhibit spectroscopic
and kinematic indications of being either old, metal poor or both.  We
propose IRAC photometry and IRS spectroscopy of these sources to
determine a means of breaking the so-called metallicity/gravity
degeneracy, and to test the first generation of cold brown dwarf
models exploring metallicity variations.