The discovery and characterisation of the extrasolar planets of WASP-South

Abstract

SuperWASP is a ground-based survey for transiting extrasolar planets. I present some of my contributions to the project's infrastructure and operations, as well as the discovery and characterisation of seven short-period, giant, transiting extrasolar planets and a 51-Jupiter-mass, transiting brown dwarf. Of particular note is the planet WASP-l7b, which is the largest known planet (Rpl = 1.99 ± 0.08 RJup ) and was the first reported to be in a retrograde orbit. WASP-17b offers one of the most extreme tests of the mechanisms suggested as responsible for the observed bloating of a subset of 'hot Jupiters'. The planet's retrograde orbit indicates that at least some hot Jupiters arrived in their current short orbits via scattering processes rather than via migration by planet-disc tidal interaction. As transiting brown dwarfs are rare, WASP-30b should prove a useful test of models. For the exoplanets WASP-22b and WASP-26b, I present spectroscopic observations of their transits. WASP-22b was found to be in a prograde orbit, but the orientation of the orbit of WASP-26b was not determined with confidence, owing to observation noise and the predicted small amplitude of the signal. I present measurements, via observations of occultations of the planets by their host stars, of the infrared thermal emission of the atmospheres of WASP-19b and WASP-17b. The atmosphere of WASP-19b appears to lack a strong atmospheric temperature inversion and inefficiently transports energy from its day-side to its night-side. For WASP-17b, the data are consistent with a low-albedo atmosphere that efficiently redistributes heat from its day-side to its night-side. For both systems, the occultation timings provide a constraint on orbital eccentricity; this proved especially useful for the WASP-17b system, as it removed the previous large uncertainty on the stellar and planetary radii.