Spitzer Space Telescope - Theoretical Research Proposal #50107


Exploring Hot Neptune Atmospheres

Principal Investigator: Jonathan Fortney
           Institution: University of California, Santa Cruz

     Technical Contact: Jonathan Fortney, University of California, Santa Cruz

Co-Investigators: 
Mark Marley, NASA Ames Research Center                                
Didier Saumon, Los Alamos National Laboratory                         

Science Category: extrasolar planets 
Dollars Approved: 125000 

Abstract:
The first transiting "hot Neptune'' GJ 436b inhabits an entirely new region of
phase space for extrasolar planetary atmospheres. This relatively cool, low-mass
object should be the first transiting extrasolar planet to sport a methane-rich
atmosphere. Like Uranus and Neptune it may also have an atmosphere highly
enriched in heavy elements. Our experience with the complex atmospheres of the
known hot-Jupiters has demonstrated that insights are best gained through the
combination of Spitzer observations and atmospheric modeling . However, no
models have investigated the atmospheres of Neptune-class exoplanets, which may
well be super metal-enriched, and span a wider range in stellar insolation and
atmospheric composition than we have previously encountered. GJ 436b the coldest
transiting planet, is in entirely new irradiation and mass regimes and is also
the target of a barrage of planned Spitzer observations. Here we propose a new
generation of atmospheric modeling to understand Spitzer observations of this
new planet and others like it.