[vsnet-chat 714] Re: CVs in triple systems?

[Taichi Kato <tkato>]

  I just remind of an X-ray binary, V1727 Cyg = 4U 2129+47.  The object,
once discovered as an X-ray source, showed periodic light modulation
(with P=0.2182579 d) just like HZ Her = Her X-1 when it was in (x-ray)
high state.  Since 1983, this object went into an extended low state,
during which only F7-type spectrum was found rather than the expected K-type
secondary having a semiamplitude of 300 km/s.  This has been taken as
an evidence for a third body in X-ray binaries -- authors also claim this
exitence may result in long-term variation of the inner orbit which may
be the cause of the switching of the X-ray activity (see ApJ 341, L75, 1989).

  Some authors also claimed 6-hour periodicity in V404 Cyg may reflect the
inner binary.

Regards,
Taichi Kato

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