Jura, M. and Muno, M. P. and Farihi, J. and Zuckerman, B. (2009) X-Ray and Infrared Observations of Two Externally Polluted White Dwarfs. Astrophysical Journal, 699 (2). pp. 1473-1479. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20090904-142002270
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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.|
|Subject Keywords:||planetary systems; white dwarfs|
|Official Citation:||X-Ray and Infrared Observations of Two Externally Polluted White Dwarfs M. Jura, M. P. Muno, J. Farihi, and B. Zuckerman 2009 ApJ 699 1473-1479 doi: 10.1088/0004-637X/699/2/1473|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||15 Sep 2009 16:39|
|Last Modified:||26 Dec 2012 11:19|
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