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Two new hot white dwarfs in a region of exceptionally low hi density |
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| Authors: | M A Barstow F Wesemael J B Holberg K Werner D A H Buckley R S Stobie G Fontaine S R Rosen S Demers R Lamontagne M J Irwin P Bergeron S O Kepler S Vennes |
| Institution: | 1 Department of Physics and Astronomy, University of Leicester, UK 2 Université de Montréal, Canada 3 University of Arizona, Tucson, USA 4 University of Kiel, Germany 5 Astronomy Department, University of Cape Town, South Africa 6 Formerly at Royal Observatory, Edinburgh, UK 7 Royal Greenwich Observatory, UK 8 Universidade Federal do Rio Grande do Sul, Brazil 9 University of California at Berkeley, USA |
| Abstract: | We report the discovery of two hot white dwarfs which have the lowest line-of-sight neutral hydrogen column densities yet measured. The stars were found independently by the ROSAT EUV, Montreal-Cambridge-Tololo, and Edinburgh-Cape surveys. Follow-up observations made using the Voyager 2 ultraviolet spectrometer reveal strong continua shortward of the 912Å Lyman limit from which we deduce that the neutral hydrogen column densities are 1.3 × 1017 and 2.0 × 1017 atoms cm−2. |
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