Title

A High C/O Ratio And Weak Thermal Inversion In The Atmosphere Of Exoplanet Wasp-12B

Abstract

The carbon-to-oxygen ratio (C/O) in a planet provides critical information about its primordial origins and subsequent evolution. A primordial C/O greater than 0.8 causes a carbide-dominated interior, as opposed to the silicate-dominated composition found on Earth; the atmosphere can also differ from those in the Solar System. The solar C/O is 0.54 (ref. 3). Here we report an analysis of dayside multi-wavelength photometry of the transiting hot-Jupiter WASP-12b (ref. 6) that reveals C/O≥1 in its atmosphere. The atmosphere is abundant in CO. It is depleted in water vapour and enhanced in methane, each by more than two orders of magnitude compared to a solar-abundance chemical-equilibrium model at the expected temperatures. We also find that the extremely irradiated atmosphere (T<2,500K) of WASP-12b lacks a prominent thermal inversion (or stratosphere) and has very efficient day-night energy circulation. The absence of a strong thermal inversion is in stark contrast to theoretical predictions for the most highly irradiated hot-Jupiter atmospheres. © 2010 Macmillan Publishers Limited. All rights reserved.

Publication Date

1-6-2011

Publication Title

Nature

Volume

469

Issue

7328

Number of Pages

64-67

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1038/nature09602

Socpus ID

78650990935 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/78650990935

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