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Title: Observations of exoplanet atmospheres
Author: Rostron, J. W.
ISNI:       0000 0004 5366 2219
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 2015
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In the past decade the field of extra-solar planetary science has moved beyond simple detections of planets outside of our Solar System into more detailed characterisations of these objects. One avenue that is at the forefront of current research is the study of extra-solar planet atmospheres. This work has focused on a subset of the current exoplanet population: transiting hot Jupiters. The large sizes, high temperatures and bright stellar hosts of these planets make them particularly amenable to atmospheric studies through techniques such as secondary eclipse observations, which can sample the planetary thermal and reflected light. Atmospheric detections have now been made for over 50 extra-solar planets. With such a population, we can begin to look for trends in the atmospheric properties of these planets, in order to shed more light on the physical processes that affect their atmospheres. It is in this context that I present the work in this thesis, which comprises secondary eclipse observations of five transiting hot Jupiter exoplanets. Secondary eclipses of WASP-3b were observed using the Spitzer Space Telescope, giving estimates of the planets thermally emitted flux at 3.6 μm, 4.5 μm and 8.0 μm. These estimates imply the planet is very hot (Teff = 2280+200−150 K) and that it may host an inverted vertical temperature profile. This system probes a cut-off in a proposed correlation between the vertical temperature structures of hot Jupiters and the chromospheric activity of their host stars. I find that my measurements for WASP-3b imply this cut-off is more complex than initial data has suggested. Secondary eclipses of the planets WASP-21b, WASP-28b and WASP-37b, all with low metallicity host stars, were also observed with the Spitzer Space Telescope, at 3.6 μm and 4.5 μm. These systems were studied to explore potential correlations between planetary spectral properties and host star metallicities. In existing data, a hint of a trend between the vertical temperature structures of planets and the metallicities of their host stars is found. However this trend is not supported by the planetary flux estimates derived for the three systems I have studied. Ground-based optical and near infra-red secondary eclipses were also observed for WASP-33b, using the ULTRACAM instrument on the William Herschel Telescope. The emission of WASP-33b, detected in the z’ band, confirms that the planet is extremely hot (Tz = 3170+90−190 K) and supports a trend found for highly irradiated planets to have systematically low albedos and poor heat redistribution properties.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QC Physics