A high C/O ratio and weak thermal inversion in the atmosphere of exoplanet WASP-12b

Nikku Madhusudhan, Joseph Harrington, Kevin B. Stevenson, Sarah Nymeyer, Christopher J. Campo, Don Pollacco, Richard G. West

Research output: Contribution to journalArticlepeer-review

214 Citations (Scopus)

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.
Original languageEnglish
Pages (from-to)64-67
Number of pages4
JournalNature
Volume469
Issue number7328
DOIs
Publication statusPublished - 06 Jan 2011

ASJC Scopus subject areas

  • General

Fingerprint

Dive into the research topics of 'A high C/O ratio and weak thermal inversion in the atmosphere of exoplanet WASP-12b'. Together they form a unique fingerprint.

Cite this