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Title: SPITZER TRANSITS OF THE SUPER-EARTH GJ1214b AND IMPLICATIONS FOR ITS ATMOSPHERE

We observed the transiting super-Earth exoplanet GJ1214b using warm Spitzer at 4.5 {mu}m wavelength during a 20 day quasi-continuous sequence in 2011 May. The goals of our long observation were to accurately define the infrared transit radius of this nearby super-Earth, to search for the secondary eclipse, and to search for other transiting planets in the habitable zone of GJ1214. We here report results from the transit monitoring of GJ1214b, including a reanalysis of previous transit observations by Desert et al. In total, we analyze 14 transits of GJ1214b at 4.5 {mu}m, 3 transits at 3.6 {mu}m, and 7 new ground-based transits in the I+z band. Our new Spitzer data by themselves eliminate cloudless solar composition atmospheres for GJ1214b, and methane-rich models from Howe and Burrows. Using our new Spitzer measurements to anchor the observed transit radii of GJ1214b at long wavelengths, and adding new measurements in I+z, we evaluate models from Benneke and Seager and Howe and Burrows using a {chi}{sup 2} analysis. We find that the best-fit model exhibits an increase in transit radius at short wavelengths due to Rayleigh scattering. Pure water atmospheres are also possible. However, a flat line (no atmosphere detected) remains among the bestmore » of the statistically acceptable models, and better than pure water atmospheres. We explore the effect of systematic differences among results from different observational groups, and we find that the Howe and Burrows tholin-haze model remains the best fit, even when systematic differences among observers are considered.« less
Authors:
;  [1] ; ;  [2] ; ; ;  [3] ;  [4] ;  [5] ;  [6]
  1. Department of Astronomy, University of Maryland, College Park, MD 20742 (United States)
  2. Institute d'Astrophysique et de Geophysique, Universite de Liege, Liege (Belgium)
  3. Department of Earth, Atmospheric and Planetary Sciences, and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)
  4. Department of Planetary Sciences and Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States)
  5. Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States)
  6. Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States)
Publication Date:
OSTI Identifier:
22126983
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 765; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTRONOMY; ASTROPHYSICS; ECLIPSE; INFRARED RADIATION; METHANE; MONITORING; PLANETARY ATMOSPHERES; PLANETS; RAYLEIGH SCATTERING; WATER; WAVELENGTHS