P D Dobbie

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Many sub-stellar companions (usually planets but also some brown dwarfs) orbit solar-type stars. These stars can engulf their sub-stellar companions when they become red giants. This interaction may explain several outstanding problems in astrophysics but it is unclear under what conditions a low mass companion will evaporate, survive the interaction(More)
  • T R Kendall, M Tamura, C G Tinney, E L Martín, M Ishii, D J Pinfield +28 others
  • 2007
Context. We report on the first ultracool dwarf discoveries from the UKIRT Infrared Deep Sky Survey (UKIDSS) Large Area Survey Early Data Release (LAS EDR), in particular the discovery of T dwarfs which are fainter and more distant than those found using the 2MASS and SDSS surveys. Aims. We aim to show that our methodologies for searching the ∼ 27 deg 2 of(More)
We argue on the basis of astrometric and spectroscopic data that the ultramassive white dwarf GD50 is associated with the star formation event that created the Pleiades and is possibly a former member of this cluster. Its cooling age (∼60Myrs) is consistent with it having evolved essentially as a single star from a progenitor with a mass M>6M ⊙ so we find(More)
  • R F Jameson, N Lodieu, S L Casewell, N P Bannister, P D Dobbie
  • 2008
We present a new method to derive the age of young (<0.7 Gyr) L dwarfs based on their near-infrared photometry, colours, and distances. The method is based on samples of L dwarfs belonging to the Upper Sco association (5 Myr), the Alpha Per (85 Myr) and Pleiades (125 Myr) clusters, and the Ursa Major (400 Myr) and Hyades (625 Myr) moving groups. We apply(More)
Optical time series photometry of the short period magnetic white dwarf + probable brown dwarf binary SDSS J121209.31 + 013627.7 reveals pulse-like variability in all bands from i ′ to u ′ , increasing towards bluer wavelengths and peaking at u ′. These modulations are most likely due to a self-eclipsing accretion hot spot on the white dwarf, rotating into(More)
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