The transiting exoplanet WASP-18b was discovered in 2008 by the Wide Angle Search for Planets (WASP) project. The Spitzer Exoplanet Target of Opportunity Program observed secondary eclipses of WASP-18b using Spitzer's Infrared Array Camera (IRAC) in the 3.6 micron and 5.8 micron bands on 2008 December 20, and in the 4.5 micron and 8.0 micron 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.
@article{arxiv.1005.1017,
title = {Spitzer Secondary Eclipses of WASP-18b},
author = {Sarah Nymeyer and Joseph Harrington and Ryan A. Hardy and Kevin B. Stevenson and Christopher J. Campo and Nikku Madhusudhan and Andrew Collier-Cameron and Thomas J. Loredo and Jasmina Blecic and William C. Bowman and Christopher B. T. Britt and Patricio Cubillos and Coel Hellier and Michael Gillon and Pierre F. L. Maxted and Leslie Hebb and Peter J. Wheatley and Don Pollacco and David R. Anderson},
journal= {arXiv preprint arXiv:1005.1017},
year = {2015}
}
Comments
10 pages, 13 figures. Electronic supplements to appear with published paper