Ultra-short-period Planets from Secular Chaos

Absence of a Metallicity Effect for Ultra-short-period Planets

Ultra-short-period (USP) planets are a newly recognized class of planets with periods shorter than one day, and radii smaller than about 2 R⊕. It has been proposed that USP planets are the solid cores of hot Jupiters that lost their gaseous envelopes due to photo-evaporation or Roche lobe overflow. We test this hypothesis by asking whether USP planets are associated with metal-rich stars, as ha...

Ultra-Short Period Double-Degenerate Binaries

We review the current observational status of the ROSAT sources RX J1914.4+2456 and RX J0806.3+1527, and the evidence that these are ultra-short period (< 10 min) binary systems. We argue that an Intermediate Polar interpretation can be ruled out, that they are indeed compact binaries with a degenerate secondary, and that the period seen in the X-ray and optical is the orbital period. A white d...

The Stability of Short-Period Extrasolar Giant Planets

A three-dimensional coupled thermosphere-ionosphere model for extrasolar giant planets (EXOTIM) has been developed. This is the first such model reported in the literature. This thesis contains an extensive description of the model and the methods adopted in modelling the different physical processes expected in the upper atmospheres and ionospheres of extrasolar giant planets. Modelling the up...

On the Tidal In ation of Short-Period Extrasolar Planets

Searching for Planets in the Hyades. Iii. the Quest for Short-period Planets

We have been using the Keck I High Resolution Spectrograph to search for planetary companions in the Hyades cluster. We selected four stars from this sample that showed significant radial velocity variability on short timescales to search for short-period planetary companions. The radial velocities of these four stars were monitored regularly with the Hobby-Eberly Telescope for approximately 2 ...