Spitzer Space Telescope - General Observer Proposal #80213


Weather on Substellar Worlds: Mapping the Atmospheres of Cool Brown Dwarfs

Principal Investigator: Jacqueline Radigan
           Institution: University of Toronto

     Technical Contact: Jacqueline Radigan, University of Toronto

Co-Investigators: 
Nicholas Cowan, Northwestern University                               
Ray Jayawardhana, University of Toronto                               
Daniel Apai, Space Telescope Science Institute                        
Stanimir Metchev, Stony Brook                                         
Adam Showman, University of Arizona                                   
Etienne Artigau, Universite de Montreal                               
Mark Marley, NASA Ames                                                
Bertrand Goldman, Heidelberg                                          
Adam Burgasser, UC San Diego                                          

Science Category: brown dwarfs/very low mass stars 
 Observing Modes: IRAC Post-Cryo Mapping
  Hours Approved: 130.0 

Abstract:
While Spitzer has already contributed significantly to the study of winds and
weather on highly irradiated extrasolar planets, the atmospheres of
free-floating brown dwarfs probe weather in an entirely different physical
regime, where global atmospheric flows arise primarily from a combination of
rapid rotation and internal convection, without external forcing. We propose to
use Warm Spitzer to monitor evolving weather patterns for a subset of brown
dwarfs displaying large-amplitude, quasi-periodic variability, indicative of
discrete and heterogeneous cloud features in their atmospheres. We plan to
obtain continuous light curves for our targets spanning several consecutive
rotations in order to map the evolution of cloud features over time and obtain
an empirical characterization of their atmospheric dynamics, including: the
spatial frequencies and timescales of cloud features, evidence for differential
rotation and wind speeds, and the dependence of weather patterns on rotation
period. In turn, the data can be used to inform atmospheric circulation models
in a mass/rotation regime never before probed, potentially shedding light on
competing circulation models for Solar System gas giant planets.