Spitzer Secondary Eclipses of WASP-18b

Nymeyer Sarah, Harrington Joseph, A. Hardy Ryan, B. Stevenson Kevin, J. Campo Christopher, Madhusudhan Nikku, Collier-Cameron Andrew, J. Loredo Thomas, Blecic Jasmina, Blecic Jasmina, B.T. Britt Christopher, Cubillos Patricio, Gillon Michael, F.L. Maxted Pierre, Hebb Leslie, J. Wheatley Peter, Don Pollacco, R. Anderson David

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61 Citations (Scopus)


The transiting exoplanet WASP-18b was discovered in 2008 by the Wide Angle Search for Planets project. The Spitzer Exoplanet Target of Opportunity Program observed secondary eclipses of WASP-18b using Spitzer's Infrared Array Camera in the 3.6 µm and 5.8 µm bands on 2008 December 20, and in the 4.5 µm and 8.0 µm bands on 2008 December 24. We report eclipse depths of 0.30% ± 0.02%, 0.39% ± 0.02%, 0.37% ± 0.03%, 0.41% ± 0.02%, and brightness temperatures of 3100 ± 90, 3310 ± 130, 3080 ± 140, and 3120 ± 110 K in order of increasing wavelength. WASP-18b is one of the hottest planets yet discovered—as hot as an M-class star. The planet's pressure-temperature profile most likely features a thermal inversion. The observations also require WASP-18b to have near-zero albedo and almost no redistribution of energy from the day side to the night side of the planet.
Original languageEnglish
Article number35
JournalAstrophysical Journal
Issue number1
Publication statusPublished - 20 Nov 2011

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics


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