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Astron. Astrophys. 349, 515-520 (1999)

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Photometric analysis of the neglected eclipsing binary system DL Cygni *

T. Borkovits and I.B. Bíró

Baja Astronomical Observatory of Bács-Kiskun County, Szegedi út, P.O. Box 766, H-6501 Baja, Hungary (borko@electra.bajaobs.hu)

Received 22 April 1999 / Accepted 28 June 1999


DL Cygni is a poorly studied early-type eclipsing binary system. In this paper we present new Kron-Cousins VR light curves obtained at Baja Astronomical Observatory in 1998. A detailed photometric analysis based on these observations was carried out by the use of the most recent version of the Wilson-Devinney (WD) code. It is found that the system is likely a strongly interacting semidetached one. We explain the irregularities of the light curves with the presence of circumstellar matter. Different solutions are presented according to the supposed positions of the circumstellar medium. We suspect that the system consists of an asynchronously rotating main-sequence primary spinned up by the infalling gas of the mass losing evolved secondary component. A period study was also carried out. The period seems to be longer than some decades ago. Due to the lack of spectroscopic information we can give only a very uncertain estimation on the absolute parameters of the binary.

One of our initial comparison stars GSC 3595-0816 is suspected to be variable.

Key words: stars: binaries: eclipsing – stars: individual: DL Cyg – stars: fundamental parameters – techniques: photometric

* Tables 3a-c are only available in electronic form at the CDS via anonymous ftp to ftp://cdsarc.u-strasbg.fr/J/A+A/349/515 ( or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/349/515

Send offprint requests to: T. Borkovits

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© European Southern Observatory (ESO) 1999

Online publication: September 2, 1999