X-Ray and Infrared Observations of Two Externally Polluted White Dwarfs
- Creators
- Jura, M.
- Muno, M. P.
- Farihi, J.
- Zuckerman, B.
Abstract
With XMM-Newton and the Spitzer Space Telescope, we obtain upper bounds to the X-ray fluxes from G29-38 and GD 362, and the 70 μm flux from G29-38. These data provide indirect evidence that G29-38 is accreting from a tidally disrupted asteroid: it is neither accreting large amounts of hydrogen and helium nor is its surrounding dusty disk being replenished from a reservoir of cold grains experiencing Poynting-Robertson drag. The upper bound to the X-ray flux from GD 362 is consistent with the estimated rate of mass accretion required to explain its pollution by elements heavier than helium. GD 362 also possesses 0.01 M_⊕ of hydrogen, an anomalously large amount for a white dwarf with a helium-dominated atmosphere. One possibility is that before the current disk was formed, this hydrogen was accreted either from ~100 Ceres-like asteroids or one large object. An alternative scenario which simultaneously explains all of GD 362's distinctive properties is that we are witnessing the consequences of the tidal destruction of a single parent body that had internal water and was at least as massive as Callisto and probably as massive as Mars.
Additional Information
© 2009. The American Astronomical Society. Received 2009 January 13; accepted 2009 May 8; published 2009 June 23. This work has been partly supported by NASA and the NSF. We thank the referee, F. Mullally, for a careful reading of the manuscript and for asking helpful questions.Attached Files
Published - Jura2009p4713Astrophys_J.pdf
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Additional details
- Eprint ID
- 15633
- Resolver ID
- CaltechAUTHORS:20090904-142002270
- NASA
- NSF
- Created
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2009-09-15Created from EPrint's datestamp field
- Updated
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2021-11-08Created from EPrint's last_modified field