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Old 04-08-2006, 08:05 AM
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sheeny (Al)
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Survival of a brown dwarf after engulfment by a red giant star

Found this first paragraph from a letter to nature in physics@nature this morning. Sounds bizarre! I'd like to read the whole thing!

Al.

Letter

Nature 442, 543-545(3 August 2006) | doi:10.1038/nature04987; Received 24 February 2006; Accepted 13 June 2006
Survival of a brown dwarf after engulfment by a red giant star

P. F. L. Maxted1, R. Napiwotzki2, P. D. Dobbie3 and M. R. Burleigh3
Top of page 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 astrophysics1,2,3,4,5 but it is unclear under what conditions a low mass companion will evaporate, survive the interaction unchanged or gain mass1,4,5. Observational tests of models for this interaction have been hampered by a lack of positively identified remnants—that is, white dwarf stars with close, sub-stellar companions. The companion to the pre-white dwarf AA Doradus may be a brown dwarf, but the uncertain history of this star and the extreme luminosity difference between the components make it difficult to interpret the observations or to put strong constraints on the models6,7. The magnetic white dwarf SDSS J121209.31 + 013627.7 may have a close brown dwarf companion8 but little is known about this binary at present. Here we report the discovery of a brown dwarf in a short period orbit around a white dwarf. The properties of both stars in this binary can be directly observed and show that the brown dwarf was engulfed by a red giant but that this had little effect on it.
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Old 04-08-2006, 10:59 AM
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Very interesting. It could make sense - if you think about it a red giant is a blown up main sequence star, so must have a pretty low density. Perhaps the outer envelope could be thin enough not to disrupt a relatively high density brow dwarf or planet, which could carry on orbiting under the surface as it were. Wouldn't like to be standing on said planet at the time however.
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