A Systematic Retrieval Analysis of Secondary Eclipse Spectra. II. A Uniform Analysis of Nine Planets and their C to O Ratios
Abstract
Secondary eclipse spectroscopy provides invaluable insights into the temperatures and compositions of exoplanetary atmospheres. We carry out a systematic temperature and abundance retrieval analysis of nine exoplanets (HD 189733b, HD 209458b, HD 149026b, GJ436b, WASP-12b, WASP-19b, WASP-43b, TrES-2b, and TrES-3b) observed in secondary eclipse using a combination of space- and ground-based facilities. Our goal with this analysis is to provide a consistent set of temperatures and compositions from which self-consistent models can be compared and to probe the underlying processes that shape these atmospheres. This paper is the second in a three part series of papers exploring the retrievability of temperatures and abundances from secondary eclipse spectra and the implications of these results for the chemistry of exoplanet atmospheres. In this investigation we present a catalogue of temperatures and abundances for H2O, CH4, CO, and CO2. We find that our temperatures and abundances are generally consistent with those of previous studies, although we do not find any statistically convincing evidence for super-solar C to O ratios (e.g., solar C/O falls in the 1σ confidence intervals in eight of the nine planets in our sample). Furthermore, within our sample we find little evidence for thermal inversions over a wide range of effective temperatures (with the exception of HD 209458b), consistent with previous investigations. The lack of evidence for inversions for most planets in our sample over such a wide range of effective temperatures provides additional support for the hypothesis that TiO is unlikely to be the absorber responsible for the formation of these inversions.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 2014
- DOI:
- 10.1088/0004-637X/783/2/70
- arXiv:
- arXiv:1309.6663
- Bibcode:
- 2014ApJ...783...70L
- Keywords:
-
- methods: statistical;
- planets and satellites: atmospheres;
- planets and satellites: composition;
- planets and satellites: gaseous planets;
- planets and satellites: individual: HD 189733b HD 149026b GJ436b WASP-12b WASP-19b WASP-43b TrES-2b TrES-3b;
- Astrophysics - Earth and Planetary Astrophysics
- E-Print:
- Accepted to ApJ