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Solar abundances of rock-forming elements, extreme oxygen and hydrogen in a young polluted white dwarf
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Farihi, J., Koester, D., Zuckerman, B., Vican, L., Gänsicke, B. T. (Boris T.), Smith, N., Walth, G. and Breedt, E. (2016) Solar abundances of rock-forming elements, extreme oxygen and hydrogen in a young polluted white dwarf. Monthly Notices of the Royal Astronomical Society, 463 (3). pp. 3186-3192. doi:10.1093/mnras/stw2182
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Official URL: http://dx.doi.org/10.1093/mnras/stw2182
Abstract
The Teff = 20 800 K white dwarf WD 1536+520 is shown to have broadly solar abundances of the major rock-forming elements O, Mg, Al, Si, Ca, and Fe, together with a strong relative depletion in the volatile elements C and S. In addition to the highest metal abundances observed to date, including log (O/He) = −3.4, the helium-dominated atmosphere has an exceptional hydrogen abundance at log (H/He) = −1.7. Within the uncertainties, the metal-to-metal ratios are consistent with the accretion of an H2O-rich and rocky parent body, an interpretation supported by the anomalously high trace hydrogen. The mixed atmosphere yields unusually short diffusion time-scales for a helium atmosphere white dwarf, of no more than a few hundred years, and equivalent to those in a much cooler, hydrogen-rich star. The overall heavy element abundances of the disrupted parent body deviate modestly from a bulk Earth pattern, and suggest the deposition of some core-like material. The total inferred accretion rate is 4.2 × 109 g s−1, and at least four times higher than for any white dwarf with a comparable diffusion time-scale. Notably, when accretion is exhausted in this system, both metals and hydrogen will become undetectable within roughly 300 Myr, thus supporting a scenario where the trace hydrogen is related to the ongoing accretion of planetary debris.
| Item Type: | Journal Article | ||||||||
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| Subjects: | Q Science > QB Astronomy Q Science > QC Physics |
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| Divisions: | Faculty of Science > Physics | ||||||||
| Library of Congress Subject Headings (LCSH): | Astrophysics, White dwarf stars, Circumstellar matter, Planetary systems | ||||||||
| Journal or Publication Title: | Monthly Notices of the Royal Astronomical Society | ||||||||
| Publisher: | Oxford University Press | ||||||||
| ISSN: | 0035-8711 | ||||||||
| Official Date: | 2 September 2016 | ||||||||
| Dates: |
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| Date of first compliant deposit: | 13 March 2017 | ||||||||
| Volume: | 463 | ||||||||
| Number: | 3 | ||||||||
| Page Range: | pp. 3186-3192 | ||||||||
| DOI: | 10.1093/mnras/stw2182 | ||||||||
| Status: | Peer Reviewed | ||||||||
| Publication Status: | Published | ||||||||
| Access rights to Published version: | Restricted or Subscription Access | ||||||||
| Funder: | Science and Technology Facilities Council (Great Britain) (STFC), United States. National Aeronautics and Space Administration (NASA), National Science Foundation (U.S.) (NSF), European Research Council (ERC), Seventh Framework Programme (European Commission) (FP7) | ||||||||
| Grant number: | 320964 (ERC) |
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