Warm spitzer photometry of the transiting exoplanets CoRoT-1 and CoRoT-2 at secondary eclipse

Drake Deming, Heather Knutson, Eric Agol, Jean Michel Desert, Adam Burrows, Jonathan J. Fortney, David Charbonneau, Nicolas B. Cowan, Gregory Laughlin, Jonathan Langton, Adam P. Showman, Nikole K. Lewis

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Abstract

We measure secondary eclipses of the hot giant exoplanets CoRoT-1 at 3.6 and 4.5ìm, and CoRoT-2 at 3.6μm, both using Warm Spitzer. We find that the Warm Spitzer mission is working very well for exoplanet science. For consistency of our analysis we also re-analyze archival cryogenic Spitzer data for secondary eclipses of CoRoT-2 at 4.5 and 8μm.We compare the total data for both planets, including optical eclipse measurements by the CoRoT mission, and ground-based eclipse measurements at 2μm, to existingmodels. Both planets exhibit stronger eclipses at 4.5 than at 3.6μm, which is often indicative of an atmospheric temperature inversion. The spectrum of CoRoT-1 is best reproduced by a 2460 K blackbody, due either to a high altitude layer that strongly absorbs stellar irradiance, or an isothermal region in the planetary atmosphere. The spectrum of CoRoT-2 is unusual because the 8μm contrast is anomalously low. Non-inverted atmospheres could potentially produce the CoRoT-2 spectrum if the planet exhibits line emission from CO at 4.5μm, caused by tidal-induced mass loss. However, the viability of that hypothesis is questionable because the emitting region cannot be more than about 30% larger than the planet's transit radius, based on the ingress and egress times at eclipse. An alternative possibility to account for the spectrum of CoRoT-2 is an additional opacity source that acts strongly at wavelengths less than 5μm, heating the upper atmosphere while allowing the deeper atmosphere seen at 8μm to remain cooler. We obtain a similar result as Gillon et al. for the phase of the secondary eclipse of CoRoT-2, implying an eccentric orbit with e cos(ù) =.0.0030 ± 0.0004.

Original languageEnglish (US)
JournalAstrophysical Journal
Volume726
Issue number2
DOIs
StatePublished - Jan 10 2011

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Keywords

  • Eclipses
  • Planetary systems
  • Techniques: photometric

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Deming, D., Knutson, H., Agol, E., Desert, J. M., Burrows, A., Fortney, J. J., Charbonneau, D., Cowan, N. B., Laughlin, G., Langton, J., Showman, A. P., & Lewis, N. K. (2011). Warm spitzer photometry of the transiting exoplanets CoRoT-1 and CoRoT-2 at secondary eclipse. Astrophysical Journal, 726(2). https://doi.org/10.1088/0004-637X/726/2/95