High Velocity Circumstellar Gas Orbiting a White Dwarf Star
B. Zuckerman, ‘Erika Le Bourdais, Beth L. Klein, Patrick Dufour, Carl Melis, Alycia J. Weinberger, Siyi Xu, Antoine B’edard, Detlev Koester
arXiv:2603.02309v1 Announce Type: new
Abstract: Numerous white dwarf stars are known to be orbited by disks of gas and dust. To date, broad, about 300 km s-1 wide, gaseous circumstellar absorption features have only been reported for the already iconic WD 1145+017, where one is witnessing the breakup of an extrasolar asteroid in real time. We report here the discovery of absorption from circumstellar gas around a second white dwarf (WD J0234-0406) with similarly broad features. The observed lines are carried by ions of Ca, Cr, Fe, Ti, Mg, Mn, Na, O, Si, Sc, Sr, Ti, and V. In addition, deep, non-photospheric lines of Si IV are seen in the ultraviolet; we compare these with Si IV lines previously seen in the ultraviolet spectra of various other white dwarfs. The apparent broadband flux of WD 1145+017 is known to change often and rapidly as chunks of the asteroid pass between the star and Earth. No such variations are seen in the brightness of WD J0234-0406. In addition, while the strength/structure of circumstellar absorption features at WD 1145+017 has changed dramatically with time, nothing similar is seen at WD J0234-0406. Excess infrared emission at WD J0234-0406 indicates the presence of circumstellar dust particles.arXiv:2603.02309v1 Announce Type: new
Abstract: Numerous white dwarf stars are known to be orbited by disks of gas and dust. To date, broad, about 300 km s-1 wide, gaseous circumstellar absorption features have only been reported for the already iconic WD 1145+017, where one is witnessing the breakup of an extrasolar asteroid in real time. We report here the discovery of absorption from circumstellar gas around a second white dwarf (WD J0234-0406) with similarly broad features. The observed lines are carried by ions of Ca, Cr, Fe, Ti, Mg, Mn, Na, O, Si, Sc, Sr, Ti, and V. In addition, deep, non-photospheric lines of Si IV are seen in the ultraviolet; we compare these with Si IV lines previously seen in the ultraviolet spectra of various other white dwarfs. The apparent broadband flux of WD 1145+017 is known to change often and rapidly as chunks of the asteroid pass between the star and Earth. No such variations are seen in the brightness of WD J0234-0406. In addition, while the strength/structure of circumstellar absorption features at WD 1145+017 has changed dramatically with time, nothing similar is seen at WD J0234-0406. Excess infrared emission at WD J0234-0406 indicates the presence of circumstellar dust particles.