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Thermal emission from WASP-24b at 3.6 and 4.5μm
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Smith, A. M. S., Anderson, D. R., Madhusudhan, N., Southworth, J., Collier Cameron, A., Blecic, J., Harrington, J., Hellier, C., Maxted, P. F. L., Pollacco, Don, Queloz, D., Smalley, B., Triaud, A. H. M . J. and Wheatley, P. J. (2012) Thermal emission from WASP-24b at 3.6 and 4.5μm. Astronomy & Astrophysics, Vol.545 . A93. doi:10.1051/0004-6361/201219294 ISSN 0004-6361.
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Official URL: http://dx.doi.org/10.1051/0004-6361/201219294
Abstract
Aims. We observe occultations of WASP-24b to measure brightness temperatures and to determine whether or not its atmosphere exhibits a thermal inversion (stratosphere). Methods. We observed occultations of WASP-24b at 3.6 and 4.5 μm using the Spitzer Space Telescope. It has been suggested that there is a correlation between stellar activity and the presence of inversions, so we analysed existing HARPS spectra in order to calculate log R′ HK for WASP-24 and thus determine whether or not the star is chromospherically active. We also observed a transit of WASP-24b in the Strömgren u and y bands, with the CAHA 2.2-m telescope. Results. We measure occultation depths of 0.159 ± 0.013 per cent at 3.6 μm and 0.202 ± 0.018 per cent at 4.5 μm. The corresponding planetary brightness temperatures are 1974 ± 71 K and 1944 ± 85 K respectively. Atmosphere models with and without a thermal inversion fit the data equally well; we are unable to constrain the presence of an inversion without additional occultation measurements in the near-IR. We find log R′ HK =-4.98 ± 0.12, indicating that WASP-24 is not a chromospherically active star. Our global analysis of new and previously-published data has refined the system parameters, and we find no evidence that the orbit of WASP-24b is non-circular. Conclusions. These results emphasise the importance of complementing Spitzer measurements with observations at shorter wavelengths to gain a full understanding of hot Jupiter atmospheres. © 2012 ESO.
Item Type: | Journal Article | ||||
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Divisions: | Faculty of Science, Engineering and Medicine > Science > Physics | ||||
Journal or Publication Title: | Astronomy & Astrophysics | ||||
Publisher: | EDP Sciences | ||||
ISSN: | 0004-6361 | ||||
Official Date: | 2012 | ||||
Dates: |
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Volume: | Vol.545 | ||||
Page Range: | A93 | ||||
DOI: | 10.1051/0004-6361/201219294 | ||||
Status: | Peer Reviewed | ||||
Publication Status: | Published | ||||
Access rights to Published version: | Restricted or Subscription Access |
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