Solar abundances of rock-forming elements, extreme oxygen and hydrogen in a young polluted white dwarf

J. Farini, D. Koester, B. Zuckerman, L. Vican, B. T. Gansicke, Nathan Smith, G. Waith, E. Breedt

Research output: Contribution to journalArticle

11 Citations (Scopus)

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 gs-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.

Original languageEnglish (US)
Pages (from-to)3186-3192
Number of pages7
JournalMonthly Notices of the Royal Astronomical Society
Volume463
Issue number3
DOIs
StatePublished - 2016

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hydrogen
rocks
oxygen
accretion
rock
metal
parent body
atmospheres
metals
helium
atmosphere
timescale
volatile element
heavy elements
coolers
debris
depletion
young
stars

Keywords

  • (WD 1536+520)
  • Circumstellar matter
  • Planetary systems
  • Stars: abundances
  • Stars: individual
  • White dwarfs

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Solar abundances of rock-forming elements, extreme oxygen and hydrogen in a young polluted white dwarf. / Farini, J.; Koester, D.; Zuckerman, B.; Vican, L.; Gansicke, B. T.; Smith, Nathan; Waith, G.; Breedt, E.

In: Monthly Notices of the Royal Astronomical Society, Vol. 463, No. 3, 2016, p. 3186-3192.

Research output: Contribution to journalArticle

Farini, J. ; Koester, D. ; Zuckerman, B. ; Vican, L. ; Gansicke, B. T. ; Smith, Nathan ; Waith, G. ; Breedt, E. / Solar abundances of rock-forming elements, extreme oxygen and hydrogen in a young polluted white dwarf. In: Monthly Notices of the Royal Astronomical Society. 2016 ; Vol. 463, No. 3. pp. 3186-3192.
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