White dwarf pollution by hydrated planetary remnants: hydrogen and metals in WDJ204713.76-125908.9

Hoskin MJ, Toloza O, Gansicke BT, Raddi R, Koester D, Pala AF, Manser CJ, Farihi J, Belmonte MT, Hollands M, Fusillo NG, Swan A (2020)

Publication Type: Journal article

Publication year: 2020

Journal

Monthly Notices of the Royal Astronomical Society Oxford University Press

Book Volume: 499

Pages Range: 171-182

Journal Issue: 1

DOI: 10.1093/mnras/staa2717

Abstract

WDJ204713.76-125908.9 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 WDJ204713.76-125908.9 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 x 10(20) 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.

Authors with CRIS profile

Roberto Raddi Dr.Karl-Remeis-Sternwarte Bamberg, Astronomisches Institut

Involved external institutions

University of Warwick GB United Kingdom (GB) Christian-Albrechts-Universität zu Kiel DE Germany (DE) University College London (UCL) GB United Kingdom (GB) Imperial College London / The Imperial College of Science, Technology and Medicine GB United Kingdom (GB)

How to cite

APA:

Hoskin, M.J., Toloza, O., Gansicke, B.T., Raddi, R., Koester, D., Pala, A.F.,... Swan, A. (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), 171-182. https://doi.org/10.1093/mnras/staa2717

MLA:

Hoskin, Matthew J., et al. "White dwarf pollution by hydrated planetary remnants: hydrogen and metals in WDJ204713.76-125908.9." Monthly Notices of the Royal Astronomical Society 499.1 (2020): 171-182.

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