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arXiv · 1109.4207

Spitzer Observations of White Dwarfs: the Missing Planetary Debris Around DZ Stars

S. Xu·M. Jura
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Abstract

We report a Spitzer/IRAC search for infrared excesses around white dwarfs, including 14 newly-observed targets and 16 unpublished archived stars. We find a substantial infrared excess around two warm white dwarfs --- J220934.84+122336.5 and WD 0843+516, the latter apparently being the hottest white dwarf known to display a close-in dust disk. Extending previous studies, we find that the fraction of white dwarfs with dust disks increases as the star's temperature increases; for stars cooler than 10,000 K, even the most heavily polluted ones do not have ~1000 K dust. There is tentative evidence that the dust disk occurrence is correlated with the volatility of the accreted material. In the Appendix, we modify a previous analysis to show that Poynting-Robertson drag might play an important role in transferring materials from a dust disk into a white dwarf's atmosphere.

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S. Xu, M. Jura. 2011-09-20. Spitzer Observations of White Dwarfs: the Missing Planetary Debris Around DZ Stars. https://doi.org/10.1088/0004-637x/745/1/88

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