On the parallax of WD 0346++246: a halo white dwarf candidate |
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| Authors: | N. C. Hambly S. J. Smartt S. T. Hodgkin R. F. Jameson S. N. Kemp W. R. J. Rolleston I. A. Steele |
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| Affiliation: | Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ; Isaac Newton Group of Telescopes, Apartado de Correos 321, 38770 Santa Cruz de La Palma, La Palma, Islas Canarias, Spain; Astronomy Group, Department of Physics and Astronomy, Leicester University, University Road, Leicester LE1 7RH; Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Islas Canarias, Spain; Department of Pure and Applied Physics, Queen's University of Belfast, Belfast BT7 1NN; Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead L41 1LD |
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| Abstract: | We present a parallax measurement for the very cool degenerate WD 0346+246, the serendipitous discovery of which was reported by Hambly et al. We find an absolute parallax of 36±5 mas, yielding a distance estimate of 28±4 pc. The resulting absolute visual magnitude of the object is M V =16.8±0.3, making it the second-lowest luminosity white dwarf currently known. We use the distance estimate and measured proper motion to show that the object has kinematics consistent with membership of the Galactic halo. WD 0346+246 is therefore by far the coolest and least luminous of only a handful of plausible halo white dwarf candidates. As such, the object has relevance to the ongoing debate concerning the results of microlensing experiments and the nature of any baryonic dark matter component to the Galactic halo residing in stellar remnants. |
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| Keywords: | stars: individual: WD 0346+246 white dwarfs Galaxy: stellar content dark matter |
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