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Originally published in Science Express on 22 March 2001
Science 27 April 2001:
Vol. 292. no. 5517, pp. 698 - 702
DOI: 10.1126/science.1059954
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Research Articles

Direct Detection of Galactic Halo Dark Matter

B. R. Oppenheimer,1* N. C. Hambly,2 A. P. Digby,2 S. T. Hodgkin,3 D. Saumon4

The Milky Way galaxy contains a large, spherical component which is believed to harbor a substantial amount of unseen matter. Recent observations indirectly suggest that as much as half of this "dark matter" may be in the form of old, very cool white dwarfs, the remnants of an ancient population of stars as old as the galaxy itself. We conducted a survey to find faint, cool white dwarfs with large space velocities, indicative of their membership in the galaxy's spherical halo component. The survey reveals a substantial, directly observed population of old white dwarfs, too faint to be seen in previous surveys. This newly discovered population accounts for at least 2 percent of the halo dark matter. It provides a natural explanation for the indirect observations, and represents a direct detection of galactic halo dark matter.

1 Astronomy Department, University of California-Berkeley, Berkeley, CA 94720-3411, USA.
2 Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ, UK.
3 Institute of Astronomy, Cambridge University, Madingley Road, Cambridge, CB3 0HA, UK.
4 Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235, USA.
*   To whom correspondence should be addressed. E-mail: bro{at}astron.berkeley.edu

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
White Dwarfs and Dark Matter.
B. K. Gibson, C. Flynn, D. S. Graff, B. R. Oppenheimer, N. C. Hambly, A. P. Digby, S. T. Hodgkin, and D. Saumon (2001)
Science 292, 2211a-2211
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