Extrasolar Planets

Search for habitable terrestrial planet transiting red dwarf GJ 1214

By Keith Cowing
July 25, 2013
Filed under
Search for habitable terrestrial planet transiting red dwarf GJ 1214

High-precision eclipse spectrophotometry of transiting terrestrial exoplanets represents a promising path for the first atmospheric characterizations of habitable worlds and the search for life outside our solar system.

The detection of terrestrial planets transiting nearby late-type M-dwarfs could make this approach applicable within the next decade, with near-to-come general facilities. In this context, we previously identified GJ 1214 as a high-priority target for a transit search, as the transit probability of a habitable planet orbiting this nearby M4.5 dwarf would be significantly enhanced by the transiting nature of GJ 1214 b, the super-Earth already known to orbit the star.

Basing on this observation, we have set-up an ambitious high-precision photometric monitoring of GJ 1214 with the Spitzer Space Telescope to probe its entire habitable zone in search of a transiting planet as small as Mars. We present here the results of this transit search. Unfortunately, we did not detect any second transiting planet. Assuming GJ 1214 hosts a habitable planet larger than Mars, our global analysis of the whole Spitzer dataset leads to a posterior no-transit probability >=97%.

Our analysis allows us to significantly improve the characterization of GJ 1214 b, to measure its occultation depth to be 70+-35 ppm at 4.5 microns, and to constrain it to be smaller than 205ppm (3-sigma upper limit) at 3.6 microns. In agreement with the plethora of transmission measurements published so far for GJ 1214 b, these emission measurements are consistent with both a metal-rich and a cloudy hydrogen-rich atmosphere.

M. Gillon, B.-O. Demory, N. Madhusudhan, D. Deming, S. Seager, H. A. Knutson, A. Lanotte, X. Bonfils, J.-M. Desert, L. Delrez, E. Jehin, J. D. Fraine, P. Magain, A. H. M. J. Triaud (Submitted on 25 Jul 2013)

Comments: 13 pages, 10 figures. Submitted to A&A

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

Cite as: arXiv:1307.6722 [astro-ph.EP]

(or arXiv:1307.6722v1 [astro-ph.EP] for this version) Submission history From: Michael Gillon [view email] [v1] Thu, 25 Jul 2013 12:42:18 GMT (1370kb)

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