engleski

V379 Cep: A Quadruple System of Two Binaries

Based on several published photometric and spectroscopic studies, V379~Cep (HR~7940) was identified as a 99.76 day eclipsing binary composed of two unusually-low-mass B type stars with projected rotational velocities of 15 and 55 km/s. Our investigation of new series of spectra and UBV observations from several observatories shows that the object is actually a quadruple system: the two observed sets of spectral lines belong to two primaries of two different binaries. The narrower lines belong to component Aa with 99.76 day orbital period while the broader ones belong to component Ba with 159.3 day period. Both binaries revolve around a common centre of gravity with a period of about 6200 days ; this motion is measurable via the change of the systemic velocities of both binaries. Our result resolves the problem of anomalous masses. It is probable that the masses of all four bodies are quite normal for somewhat evolved stars. But the ultimate test must come from interferometric resolution of the AB pair of binaries ; it might be expected that the separation can reach about 40 mas. There is a very good chance that the continuing systematic observations will permit accurate determination of all four individual masses.

eclipsing binaries V379 Cep; spectroscopic binaries; fundamental parameters

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