Re-evaluating WASP-12b: Strong emission at 2.315 μm, deeper occultations, and an isothermal atmosphere

Ian J.M. Crossfield, Travis Barman, Brad M.S. Hansen, Ichi Tanaka, Tadayuki Kodama

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93 Citations (Scopus)


We revisit the atmospheric properties of the extremely hot Jupiter WASP-12b in light of several new developments. First, we present new narrowband (2.315 μm) secondary eclipse photometry, which exhibits a planet/star flux ratio of 0.45% ± 0.06%, corresponding to a brightness temperature of 3640 ± 230 K; second, recent Spitzer/Infrared Array Camera and Hubble Space Telescope/Wide Field Camera 3 observations; and third, a recently observed star only 1″ from WASP-12, which has diluted previous observations and which we further characterize here. We correct past WASP-12b eclipse measurements for the presence of this object, and we revisit the interpretation of WASP-12b's dilution-corrected emission spectrum. The resulting planetary emission spectrum is well approximated by a blackbody, and consequently our primary conclusion is that the planet's infrared photosphere is nearly isothermal. Thus, secondary eclipse spectroscopy is relatively ill suited to constrain WASP-12b's atmospheric abundances, and transmission spectroscopy may be necessary to achieve this goal.

Original languageEnglish
Article number140
JournalAstrophysical Journal
Issue number2
Publication statusPublished - 2012 Dec 1


  • eclipses
  • infrared: planetary systems
  • stars: individual (WASP-12, Bergfors-6)
  • techniques: photometric
  • techniques: spectroscopic


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