The 3.6-8.0 μm broadband emission spectrum of HD 209458b: Evidence for an atmospheric temperature inversion

Heather A. Knutson, David Charbonneau, Lori E. Allen, Adam S. Burrows, S. Thomas Megeath

Research output: Contribution to journalArticle

315 Scopus citations

Abstract

We estimate the strength of the bandpass-integrated thermal emission from the extrasolar planet HD 209458b at 3.6, 4.5, 5.8, and 8.0 μm using the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. We observe a single secondary eclipse simultaneously in all four bandpasses and find relative eclipse depths of 0.00094 ± 0.00009, 0.00213 ± 0.00015, 0.00301 ± 0.00043, and 0.00240 ± 0.00026, respectively. These eclipse depths reveal that the shape of the inferred emission spectrum for the planet differs significantly from the predictions of standard atmosphere models; instead, the most plausible explanation would require the presence of an inversion layer high in the atmosphere leading to significant water emission in the 4.5 and 5.8 μm bandpasses. This is the first clear indication of such a temperature inversion in the atmosphere of a hot Jupiter, as previous observations of other planets appeared to be in reasonably good agreement with the predictions of models without such an inversion layer.

Original languageEnglish (US)
Pages (from-to)526-531
Number of pages6
JournalAstrophysical Journal
Volume673
Issue number1
DOIs
StatePublished - Jan 20 2008

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • Eclipses
  • Planetary systems
  • Stars: individual (HD 209458b)
  • Techniques: photometric

Fingerprint Dive into the research topics of 'The 3.6-8.0 μm broadband emission spectrum of HD 209458b: Evidence for an atmospheric temperature inversion'. Together they form a unique fingerprint.

  • Cite this