The Present data of V382 Cyg is representable only by an overcontact model with fill-out parameter of 22%. Most probably, the overcontactness of the system was formed by;
The mass ratio q is known to be a key parameter in the light curve solutions of eclipsing binaries. To determine the photometric mass ratio of the system, we applied a q-search procedure on our new data. Our result (q=0.68) verifies the spectroscopic mass ratios given by Popper & Hill (1991) and Harries et al. (1997). According to Leung (1988), there is very good agreement, in general, between the photometric mass ratios and the spectroscopic mass ratios derived from cross-correlation techniques. Our result confirms this conclusion.
A period study using the new data together with published times
of eclipse minima revealed an increase of about 3.28 s per century
in the orbital period of the system. The secular period increase of
contact binary systems is possible only by mass transfer from the
less massive to the more massive component. By using the conservative
mass transfer hypothesis, the mass transfer rate was found to be
about . This rate should be the minimum
value, because any mass and momentum loss from such a spin-orbit
coupled contact binary system tends to decrease the orbital period.
Considerable mass loss due to a strong interacting wind from V382 Cyg
is inevitable. The light curve variability occuring on the rising
branches of the eclipses and in the depths of the secondary minima
(see Landolt 1975) and the P Cygni profiles of certain UV lines
(see Koch et al. 1979) are all indicative of mass loss from
the system. Koch et al. (1979) estimated a mass loss rate of
, although rates of
are expected for O6.5 main-sequence
stars (cf. Howarth & Prinja 1989).
In summary, the secular period increase of the system
requires
a very large rate, at least , of
mass transfer from the less massive to the more massive component.
The mass ratio of the system is already reversed. The orbital period
of the system initially decreased very rapidly and the contact configuration
should have been formed before the mass ratio reversal. The period
should have been increasing since mass ratio reversal of the system.
The mass loss from the system should decrease the rate of period
increase of the system. The short term variations in the
diagram should be caused by irregularities in the mass
transfer and mass loss.
This work was partly supported by the Scientific and Technical Research Council of Turkey under TBAG-AY/78.
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