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Detection of weak cirmcumstellar gas around the Daz White Dwarf WD 1124-293 : evidence for the accretion of multiple asteroids
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Debes, J. H., Kilic, M., Faedi, Francesca, Shkolnik, E. L., Lopez-Morales, M., Weinberger, A. J., Slesnick, C. and West, Richard G. (2012) Detection of weak cirmcumstellar gas around the Daz White Dwarf WD 1124-293 : evidence for the accretion of multiple asteroids. The Astrophysical Journal, Volume 754 (Number 1). Article number 59. doi:10.1088/0004-637X/754/1/59
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Official URL: http://dx.doi.org/10.1088/0004-637X/754/1/59
Abstract
Single metal-polluted white dwarfs with no dusty disks are believed to be actively accreting metals from a circumstellar disk of gas caused by the destruction of asteroids perturbed by planetary systems. We report, for the first time, the detection of circumstellar Ca II gas in absorption around the DAZ WD 1124-293, which lacks an infrared excess. We constrain the gas to >7 R WD and <32000 AU, and estimate it to be at ~54 R WD, well within WD 1124-293's tidal disruption radius. This detection is based on several epochs of spectroscopy around the Ca II H and K lines (λ = 3968 Å, 3933 Å) with the MIKE spectrograph on the Magellan/Clay Telescope at Las Campanas Observatory. We confirm the circumstellar nature of the gas by observing nearby sightlines and finding no evidence for gas from the local interstellar medium. Through archival data we have measured the equivalent width of the two photospheric Ca lines over a period of 11 years. We see <5%-7% epoch-to-epoch variation in equivalent widths over this time period, and no evidence for long term trends. The presence of a circumstellar gas implies a near edge-on inclination to the system, thus we place limits to short period transiting planetary companions with R > R ⊕ using the Wide Angle Search for Planets survey. The presence of gas in orbit around WD 1124-293 implies that most DAZs could harbor planetary systems. Since 25%-30% of white dwarfs show metal line absorption, the dynamical process for perturbing small bodies must be robust.
| Item Type: | Journal Article | ||||
|---|---|---|---|---|---|
| Divisions: | Faculty of Science, Engineering and Medicine > Science > Physics | ||||
| Journal or Publication Title: | The Astrophysical Journal | ||||
| Publisher: | Institute of Physics Publishing, Inc. | ||||
| ISSN: | 0004-637X | ||||
| Official Date: | July 2012 | ||||
| Dates: |
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| Volume: | Volume 754 | ||||
| Number: | Number 1 | ||||
| Article Number: | Article number 59 | ||||
| DOI: | 10.1088/0004-637X/754/1/59 | ||||
| Status: | Peer Reviewed | ||||
| Publication Status: | Published | ||||
| Access rights to Published version: | Restricted or Subscription Access |
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