We report results of a spectral monitoring campagne of the DAB white dwarf HS 0209+0832, for which helium line profile variations were reported earlier (Heber et al. 1997). This finding is confirmed by our discovery of a second epoch (October 1997) of unusually low helium line strength and of their subsequent recovery. The observed changes in line strength correspond to a variation of the (average) helium abundance by a factor of 2.
|Title of host publication||In: Procs of the 12th European Workshop on White Dwarf Stars, ASP Conference Proceedings 226|
|Publisher||Astronomical Society of the Pacific|
|Publication status||Published - 2001|