The DB white dwarfs - I. The He I 4388 + 4471 + 4516 blend
Open Access
- 1 July 1983
- journal article
- Published by Oxford University Press (OUP) in Monthly Notices of the Royal Astronomical Society
- Vol. 203 (3) , 887-902
- https://doi.org/10.1093/mnras/203.3.887
Abstract
We discuss spectrophotometric observations of 7 DB white dwarfs obtained at a resolution of ∼1.6 Å. Model atmosphere calculations are presented which show that the ratio of the equivalent widths W(λ4388)/W(λ4388 + 4471 + 4516) is a good indicator of gravity over the entire DB temperature range. An analysis of the observations using this line ratio yields a mean gravity 〈log g〉 ∼ 8.0 and mean mass 〈M〉 ∼ 0.58 M⊙ similar to the values found for the DA white dwarfs. Several He I lines are found to have sharp cores implying a mean value for the projected rotational velocity of ≲ 135 km s−1. The possibility that a magnetic field combined with rotation may inhibit accretion in DB white dwarfs is discussed.Keywords
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