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Abstract: We have identified two moderately hot ~18000-22000K white dwarfs,SDSSJ1228+1040 and SDSSJ1043+0855, which exhibit double-peaked emission linesin the CaII 8600A triplet. These line profiles are unambiguous signatures ofgaseous discs with outer radii of ~1Rsun orbiting the two white dwarfs. Bothstars accrete from the circumstellar material, resulting in large photosphericMg abundances. The absence of hydrogen emission from the discs, and heliumabsorption in the white dwarf photospheres demonstrates that the circumstellarmaterial is depleted in volatile elements, and the most likely origin of thesegaseous rings are tidally disrupted rocky asteroids. The relatively high massof SDSSJ1228+1040 implies that planetary systems can not only form around4-5Msun stars, but may also survive their post main-sequence evolution.



Author: B.T. Gaensicke, T.R. Marsh, J. Southworth, A. Rebassa-Mansergas

Source: https://arxiv.org/







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