Spitzer Space Telescope - Directors Discretionary Time Proposal #260


Infrared Photometry of the Very Hot Jupiter Orbiting HD 189733

Principal Investigator: Drake Deming
           Institution: NASA's Godddard Space Flight Center

Co-Investigators: 
Sara Seager, Carnegie DTM                                             
Joseph Harrington, Cornell U.                                         
L.Jeremy Richardson, Goddard Space Flight Center                      

Science Category: extrasolar planets 
 Observing Modes: IrsPeakupImage 
  Hours Approved: 6.0 

Abstract:
The recently announced transiting extrasolar planet orbiting HD 189733
is a very hot Jupiter with an orbital period of only 2.2 days.  It is
not only the brightest representative of this dynamical class of
extrasolar planets, it is the brightest of all known transiting
extrasolar planets in the infrared.  By comparing HD 189733b to
members of the hot Jupiter class with somewhat longer orbital periods,
Spitzer observations can provide true comparative exoplanetology.
This will ultimately allow new insights and raise new questions - into
the effect of initial mass on the planet's spectrum, on how it evolves
in the presence of stellar irradiation, and on the physical origin of
different dynamical classes of close-in giant planets.  We propose to
measure the planet's brightness temperature at 16 microns, by
detecting the secondary eclipse to very high S/N, using IRS peak-up
imaging photometry.  Our observations will measure the planet's
brightness temperature to a precision of ±13K, an order of magnitude
more precise than our MIPS measurement of HD 209458b.  Achieving this
precision will enable the best possible suite of detailed follow-up
studies (e.g., spectroscopy) to be planned for GO-3.