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dc.contributor.advisorCameron, A. C.
dc.contributor.authorBrown, David John Alexander
dc.description.abstractThanks to a range of discovery methods that are sensitive to different regions of parameter space, we now know of over 900 planets in over 700 planetary systems. This large population has allowed exoplanetary scientists to move away from a focus on simple discovery, and towards efforts to study the bigger pictures of planetary system formation and evolution. The interactions between planets and their host stars have proven to be varied in both mechanisms and scope. In particular, tidal interactions seem to affect both the physical and dynamical properties of planetary systems, but characterising the broader implications of this has proven challenging. In this thesis I present work that investigates different aspects of tidal interactions, in order to uncover the scope of their influence of planetary system evolution. I compare two different age calculation methods using a large sample of exoplanet and brown dwarf host stars, and find a tendency for stellar model fitting to supply older age estimates than gyrochronology, the evaluation of a star's age through its rotation (Barnes 2007). Investigating possible sources of this discrepancy suggests that angular momentum exchange through the action of tidal forces might be the cause. I then select two systems from my sample, and investigate the effect of tidal interactions on their planetary orbits and stellar spin using a forward integration scheme. By fitting the resulting evolutionary tracks to the observed eccentricity, semi-major axis and stellar rotation rate, and to the stellar age derived from isochronal fitting, I am able to place constraints on tidal dissipation in these systems. I find that the majority of evolutionary histories consistent with my results imply that the stars have been spun up through tidal interactions as the planets spiral towards their Roche limits. I also consider the influence of tidal interactions on the alignment between planetary orbits and stellar spin, presenting new measurements of the projected spin-orbit alignment angle, λ, for six hot Jupiters. I consider my results in the context of the full ensemble of measurements, and find that they support a previously identified trend in alignment angle with tidal timescale, implying that tidal realignment might be responsible for patterns observed in the λ distribution.en_US
dc.publisherUniversity of St Andrews
dc.relationBrown, D. J. A. et al. (2011), Monthly Notices of the Royal Astronomical Society, Issue 415, pp. 605-618en_US
dc.relationBrown, D. J. A. et al. (2012), Monthly Notices of the Royal Astronomical Society, Issue 423, pp. 1503-1520en_US
dc.relationBrown, D. J. A. et al. (2012), Astrophysical Journal, Issue 760, pp. 139en_US
dc.subjectExtra-solar planetsen_US
dc.subjectPlanetary systemsen_US
dc.subjectTidal interactionsen_US
dc.subjectRadial velocitiesen_US
dc.subjectStellar agesen_US
dc.subject.lcshExtrasolar planetsen_US
dc.titleThe effects of tidal interactions on the properties and evolution of hot-Jupiter planetary systems.en_US
dc.type.qualificationnamePhD Doctor of Philosophyen_US
dc.publisher.institutionThe University of St Andrewsen_US

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