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It is noted that the star HZ 9, a member of the Hyades, is a spectroscopic binary with a period of 0.56433 day. One component is a DA white dwarf and the other is a late main-sequence M star (roughly dM4.5e). The system is similar to V471 Tauri and PG 1413+01; like them, it is probably a post-common-envelope binary.
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Lanning et al. (1981) studied this question.
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