Publ. Astron. Soc. Pac., 111, 702-708 (1999/June-0)
The parentage of magnetic white dwarfs: implications from their space motions.
ANSELOWITZ T., WASATONIC R., MATTHEWS K., SION E.M. and McCOOK G.P.
Abstract (from CDS):
We have examined the statistical properties, cooling ages, and vector components of the three-dimensional space motion U, V, W for the enlarged sample of 53 magnetic white dwarfs contained in the fourth edition of the Catalog of Spectroscopically Identified White Dwarfs (McCook & Sion). Their cooling ages range from 2 million years to 12.6 billion years. A comparison of the total kinematic samples of magnetics and DA stars over the same luminosity range 10.0<Mv<16.0 reveals a velocity dispersion σ(v)=39 km.s–1 for 256 DA stars compared with σ(v)=23 km.s–1 for 26 magnetic degenerates with space motions. These results underscore the conclusion that the sample of magnetic white dwarfs appears to be predominantly descended from a young disk stellar population subcomponent characterized by relatively small motions with respect to the Sun. This suggests both links to upper main-sequence Ap/Bp progenitors but possibly also massive ``near miss'' pulsar progenitors. We find preliminary evidence that the magnetic white dwarfs show a peculiar distribution in UV velocity space relative to other spectroscopic subgroups of white dwarfs. However, there is little evidence of a difference in velocity dispersion among the hot and cool magnetic degenerates, despite their having vastly different cooling ages. This may be taken as indirect evidence that the magnetics represent a sample of mixed evolutionary progeny.
Stars: Kinematics - Stars: Magnetic Fields - Stars: White Dwarfs
Tables 1 and 2 : 0000-343 is WD 0000-3430, 0823-253 is 1RXS J082335. 2-252522, 1008+290 not in the WD catalogue, 1440+752 is HS 1440+7518, 2201-225 is HE 2201-2250, 0003- 570 is HE 0003-5701, 0026-215 is HE 0026-2150, 0107-016 is HE 0107-0158. G 243 -4 misprint for 234-4.
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