Solar abundances of rock-forming elements, extreme oxygen and hydrogen in a young polluted white dwarf
AffiliationUniv Arizona, Steward Observ
stars: individual: (WD 1536+520)
MetadataShow full item record
PublisherOXFORD UNIV PRESS
CitationSolar abundances of rock-forming elements, extreme oxygen and hydrogen in a young polluted white dwarf 2016, 463 (3):3186 Monthly Notices of the Royal Astronomical Society
Rights© 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at firstname.lastname@example.org.
AbstractThe T-eff = 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 x 10(9) 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.
VersionFinal published version
SponsorsMMT; WHT [SW2014a39]; STFC via an Ernest Rutherford Fellowship; NASA grant; NSF pre-doctoral fellowship; ERC under the European Union's 7th Framework Programme