1112.5145 (D. R. Anderson et al.)

Thermal emission at 3.6-8 micron from WASP-19b: a hot Jupiter without a stratosphere orbiting an active star    [PDF]

D. R. Anderson, A. M. S. Smith, N. Madhusudhan, P. J. Wheatley, A. Collier Cameron, C. Hellier, C. Campo, M. Gillon, J. Harrington, P. F. L. Maxted, D. Pollacco, D. Queloz, B. Smalley, A. H. M. J. Triaud, R. G. West

We report detection of thermal emission from the exoplanet WASP-19b at 3.6, 4.5, 5.8 and 8.0 micron. We used the InfraRed Array Camera on the Spitzer Space Telescope to observe two occultations of WASP-19b by its host star. We combine our new detections with previous measurements of WASP-19b's emission at 1.6 and 2.09 micron to construct a spectral energy distribution of the planet's dayside atmosphere. By comparing this with model-atmosphere spectra, we find that the dayside atmosphere of WASP-19b lacks a strong temperature inversion. As WASP-19 is an active star (log RHK = -4.50 +/- 0.03), this finding supports the hypothesis of Knutson, Howard & Isaacson (2010) that inversions are suppressed in hot Jupiters orbiting active stars. The available data are unable to differentiate between a carbon-rich and an oxygen-rich atmosphere.

View original: http://arxiv.org/abs/1112.5145