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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)
We present heavy element abundance measurements for 16 DAO white dwarfs, determined from Far-Ultraviolet Spectroscopic Explorer (FUSE) spectra. Evidence of absorption by heavy elements was found in the spectra of all the objects. Measurements were made using models that adopted the temperatures, gravities and helium abundances determined from both optical(More)
The bright, soft X-ray spectrum Seyfert 1 galaxies Akn 564 and Ton S180 were monitored for 35 days and 12 days respectively with ASCA and RXTE (and EUVE for Ton S180). These represent the most intensive X-ray monitoring of any such soft spectrum Seyfert 1 to date. Light curves were constructed for Ton S180 in six bands spanning 0.1–10 keV and for Akn 564 in(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)
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 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)
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