American Astronomical Society, Astrophysical Journal, 1(679), p. L29-L32, 2008
DOI: 10.1086/589151
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In this Letter we demonstrate that the puzzling bright peak in the luminosity function of the white dwarf (WD) cooling sequence of NGC 6791 can be naturally accounted for if ~34% of the observed WDs are WD+WD binary systems. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555.