Spitzer Space Telescope - General Observer Proposal #80073


Life on the Edge: Planetary Atmospheres in Extreme Environments

Principal Investigator: Heather Knutson
           Institution: UC Berkeley

     Technical Contact: Heather Knutson, UC Berkeley

Co-Investigators: 
Drake Deming, NASA Goddard                                            
Kamen Todorov, Penn State University                                  
Jean-Michel Desert, Harvard University                                
Eric Agol, University of Washington                                   
Nicolas Cowan, Northwestern University                                
Adam Burrows, Princeton University                                    
Jonathan Fortney, University of California, Santa Cruz                
Andrew Howard, University of California, Berkeley                     
Gregory Laughlin, University of California, Santa Cruz                
Jonathan Langton, Principia College                                   
Adam Showman, University of Arizona                                   
Nikole Lewis, University of Arizona                                   

Science Category: extrasolar planets 
 Observing Modes: IRAC Post-Cryo Mapping
  Hours Approved: 596.4 

Abstract:
Studies of extrasolar planets have been moving at an ever-accelerating pace,
with more than one hundred known transiting planet systems and hundreds of new
planet candidates from missions such as Kepler and CoRoT waiting in the wings.
Ongoing efforts with the Hubble and Spitzer Space Telescopes, as well as from
the ground, have allowed us to characterize the atmospheres of these planets in
unprecedented detail and have revealed a surprisingly diverse array of
atmosphere properties. We propose to address some of the most hotly debated
questions in the field using a subset of bright, recently discovered transiting
planet systems, which provide the most optimal targets for detailed
characterization. These questions include: What is the mechanism responsible for
maintaining the large day-night temperature gradients observed for some tidally
locked hot Jupiters? Are MHD effects such as Lorentz braking and Ohmic
dissipation important in the hottest planetary atmospheres? What sets the
balance between methane and CO in cooler atmospheres, and how important is
photochemistry and other non-equilibrium processes? Although it would be natural
to extend these same studies down into the super-Earth (< 10 M_earth) mass
range, there is currently only one system (GJ 1214) that is suitable for
detailed characterization. We therefore propose to carry out a search for
transits of known, low-mass radial velocity planets orbiting bright stars, with
a 52% probability of finding a new transiting super-Earth. Because the vast
majority of Kepler- and CoRoT-detected planets in this mass range are too faint
for detailed atmosphere studies, such systems will be crucial in allowing us to
characterize the atmospheres of smaller and more earth-like worlds.