Girven, J;
Brinkworth, CS;
Farihi, J;
Gänsicke, BT;
Hoard, DW;
Marsh, TR;
Koester, D;
(2012)
Constraints on the lifetimes of disks resulting from tidally destroyed rocky planetary bodies.
Astrophysical Journal
, 749
(2)
, Article 154. 10.1088/0004-637X/749/2/154.
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Abstract
Spitzer IRAC observations of 15 metal-polluted white dwarfs reveal infrared excesses in the spectral energy distributions of HE0110-5630, GD61, and HE1349-2305. 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 [tdisk(yr)] = 5.6 ± 1.1 (ranging from 3 × 104 to 5 × 106yr). 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.
| Type: | Article |
|---|---|
| Title: | Constraints on the lifetimes of disks resulting from tidally destroyed rocky planetary bodies |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1088/0004-637X/749/2/154 |
| Publisher version: | http://dx.doi.org/10.1088/0004-637X/749/2/154 |
| Language: | English |
| Additional information: | Copyright © 2012 The American Astronomical Society. All rights reserved. |
| Keywords: | circumstellar matter; minor planets, asteroids: general; planetary systems; stars: abundances; white dwarfs |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1477434 |
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