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Constraints on the Lifetimes of Disks Resulting from Tidally Destroyed Rocky Planetary Bodies

Girven, J. and Brinkworth, C. S. and Farihi, J. and Gänsicke, B. T. and Hoard, D. W. and Marsh, T. R. and Koester, D. (2012) Constraints on the Lifetimes of Disks Resulting from Tidally Destroyed Rocky Planetary Bodies. Astrophysical Journal, 749 (2). Art. No. 154. ISSN 0004-637X. doi:10.1088/0004-637X/749/2/154.

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Spitzer IRAC observations of 15 metal-polluted white dwarfs reveal infrared excesses in the spectral energy distributions of HE 0110–5630, GD 61, and HE 1349–2305. All three of these stars have helium-dominated atmospheres, and their infrared emissions are consistent with warm dust produced by the tidal destruction of (minor) planetary bodies. This study brings the number of metal-polluted, helium and hydrogen atmosphere white dwarfs surveyed with IRAC to 53 and 38, respectively. It also nearly doubles the number of metal-polluted helium-rich white dwarfs found to have closely orbiting dust by Spitzer. From the increased statistics for both atmospheric types with circumstellar dust, we derive a typical disk lifetime of log [t disk(yr)] = 5.6 ± 1.1 (ranging from 3 × 10^4 to 5 × 10^6 yr). This assumes a relatively constant rate of accretion over the timescale where dust persists, which is uncertain. We find that the fraction of highly metal-polluted helium-rich white dwarfs that have an infrared excess detected by Spitzer is only 23%, compared to 48% for metal-polluted hydrogen-rich white dwarfs, and we conclude from this difference that the typical lifetime of dusty disks is somewhat shorter than the diffusion timescales of helium-rich white dwarf. We also find evidence for higher time-averaged accretion rates onto helium-rich stars compared to the instantaneous accretion rates onto hydrogen-rich stars; this is an indication that our picture of evolved star-planetary system interactions is incomplete. We discuss some speculative scenarios that can explain the observations.

Item Type:Article
Related URLs:
URLURL TypeDescription
Farihi, J.0000-0003-1748-602X
Gänsicke, B. T.0000-0002-2761-3005
Hoard, D. W.0000-0002-6800-6519
Marsh, T. R.0000-0002-2498-7589
Additional Information:© 2012 American Astronomical Society. Received 2012 January 12; accepted 2012 February 16; published 2012 April 3. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, Caltech, under NASA contracts 1407 and 960785. Some data presented herein are part of the Sloan Digital Sky Survey, which is managed by the Astrophysical Research Consortium for the Participating Institutions ( This work makes use of data products from the TwoMicron All Sky Survey, which is a joint project of the University of Massachusetts and IPAC/Caltech, funded by NASA and the NSF. A small part of the work uses data products from the Wide-field Infrared Survey Explorer, which is a joint project of the UCLA, and JPL/Caltech, funded by the NASA.
Funding AgencyGrant Number
Subject Keywords:circumstellar matter; minor planets, asteroids: general; planetary systems; stars: abundances; white dwarfs
Issue or Number:2
Record Number:CaltechAUTHORS:20120514-101340712
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Official Citation:Constraints on the Lifetimes of Disks Resulting from Tidally Destroyed Rocky Planetary Bodies. J. Girven et al. 2012 ApJ 749 154
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:31446
Deposited By: Ruth Sustaita
Deposited On:15 May 2012 15:05
Last Modified:09 Nov 2021 19:53

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