Detection of a He I 4517 A absorption feature in the DB white dwarf D 190

The spectrum of GD 190 (EG 193), a strong-lined DB white dwarf, is shown to contain an absorption feature at 4517 A in the redward wing of the He I lambda 4471 line. This feature, which is believed to be due to the forbidden 2 /sup 3/P--4 /sup 3/P transition in He I, has not been detected previously in DB white dwarfs. While its presence is predicted from model atmosphere calculations, agreement between theory and observation remains qualitative. It is possible that the lambda 4517 feature may provide a valuable gravity discriminant at least for hot DB white dwarfs. (auth)