Hoskin, MJ;
Toloza, O;
Gansicke, BT;
Raddi, R;
Koester, D;
Pala, AF;
Manser, CJ;
... Swan, A; + view all
(2020)
White dwarf pollution by hydrated planetary remnants: hydrogen and metals in WDJ204713.76-125908.9.
Monthly Notices of the Royal Astronomical Society
, 499
(1)
pp. 171-182.
10.1093/mnras/staa2717.
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Abstract
WD J204713.76–125908.9 is a new addition to the small class of white dwarfs with helium-dominated photospheres that exhibit strong Balmer absorption lines and atmospheric metal pollution. The exceptional abundances of hydrogen observed in these stars may be the result of accretion of water-rich rocky bodies. We obtained far-ultraviolet and optical spectroscopy of WD J204713.76–125908.9 using the Cosmic Origin Spectrograph on-board the Hubble Space Telescope and X-shooter on the Very Large Telescope, and identify photospheric absorption lines of nine metals: C, O, Mg, Si, P, S, Ca, Fe, and Ni. The abundance ratios are consistent with the steady-state accretion of exo-planetesimal debris rich in the volatile elements carbon and oxygen, and the transitional element sulphur, by factors of 17, 2, and 4, respectively, compared to the bulk Earth. The parent body has a composition akin to Solar system carbonaceous chondrites, and the inferred minimum mass, 1.6 × 1020 g, is comparable to an asteroid 23 km in radius. We model the composition of the disrupted parent body, finding from our simulations a median water mass fraction of 8 per cent.
| Type: | Article |
|---|---|
| Title: | White dwarf pollution by hydrated planetary remnants: hydrogen and metals in WDJ204713.76-125908.9 |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1093/mnras/staa2717 |
| Publisher version: | https://doi.org/10.1093/mnras/staa2717 |
| Language: | English |
| Additional information: | This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | stars: abundances – stars: individual: WDJ204713.76-125908.94 – planetary systems – white dwarfs |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10117486 |
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