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Paper: Is the Oxygen-Rich White Dwarf SDSS J1242+5226 Accreting Water-Abundant Debris?
Volume: 493, 19th European Workshop on White Dwarfs
Page: 273
Authors: Raddi, R.; Gänsicke, B. T.; Koester, D.; Farihi, J.; Hermes, J. J.; Scaringi, S.; Breedt, E.; Girven, J.
Abstract: We identified a new strongly metal polluted white dwarf, and report the determination of hydrogen and traces of O, Na, Mg, Si, Ca, Ti, Cr, and Fe in a helium-dominated atmosphere. The four most common rock-forming elements, i.e. O, Mg, Si, and Fe embody almost entirely the 1024 g of metals that are mixed in the convection zone. Oxygen is the most abundant of these four elements and we estimate that about 50–60% of it is in excess with respect to the amount expected from the accretion of mineral oxides. We suggest that the parent body that of the planetary debris detected in this white dwarf was composed by 28–48% water. We also note that a handful of other known debris-polluted white dwarfs, like GD 61, GD 16, and GD 362 may be the actively accreting examples of a larger number of stars that previously accreted water-rich debris. We speculate that the hydrogen content of DBA and DZ white dwarfs could have a similar origin.
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