Spitzer Space Telescope - General Observer Proposal #40423


The Structure of the Lone Core-Dominated Exoplanet

Principal Investigator: David Charbonneau
           Institution: Harvard University

     Technical Contact: David Charbonneau, Harvard University

Co-Investigators: 
Heather Knutson, Harvard University                                   
Matthew Holman, Smithsonian Astrophysical Observatory                 
Joshua Winn, Massachusetts Institute of Technology                    
Eric Agol, University of Washington                                   
Jonathan Fortney, NASA Ames Research Center                           
Ronald Gilliland, Space Telescope Science Institute                   

Science Category: extrasolar planets 
 Observing Modes: IracMap 
  Hours Approved: 8.0 

Abstract:
Of all the known transiting exoplanets, one is unique in that its large density
implies the presence of a massive central core of heavy elements. Although this
conclusion would seem to support the core-accretion theory of planet formation
as opposed to coreless alternatives such as gravitational instability, the core
is much larger than expected. Many theoretical investigations have attempted to
explain why this planet did not accrete gas efficiently or, alternatively, how
it lost much of its gas envelope at a later stage. Surprisingly, these
conclusions hinge on an estimate of the planet radius that is only poorly
determined by current standards. We propose to fix this problem by obtaining an
ultra precise IRAC 8-micron light curve of a single planetary transit. We
simulate the expected data and conduct a complete end-to-end analysis. We
demonstrate that we will improve the estimate of the planetary radius to the
level required to conclude beyond the shadow of a doubt that a massive core lies
at the heart of this puzzling world.