Astron. Astrophys. Suppl. Ser.
Volume 147, Number 2, December I 2000
|Page(s)||243 - 249|
|Published online||15 December 2000|
Period changes in W UMa-type eclipsing binaries: DK Cygni, V401 Cygni, AD Phoenicis and Y Sextantis*
Astronomical Institute, Charles University Prague, CZ-180 00 Praha 8, V Holešovičkách 2, Czech Republic e-mail: firstname.lastname@example.org
2 Astronomical Institute, Academy of Sciences of Czech Republic, CZ-251 65 Ondřejov, Czech Republic
Send offprint request to: M. Wolf
Accepted: 11 September 2000
We present a period analysis of the four well-known W UMa-type eclipsing binaries DK Cyg (), V401 Cyg (), AD Phe () and Y Sex (). Several new times of minimum light, recorded photoelectrically, have been gathered. Analysis of all available eclipse timings of the DK Cygni and V401 Cygni has confirmed a significant increase in period of and day cycle-1, respectively. A simultaneous solution of the and R light curves was computed for V401 Cyg using the Binary Maker 2.0 synthetic lightcurve software. This solution indicates that V401 Cyg is in contact with a filing factor of 46%. The period of AD Phe seems to be constant. Period changes of Y Sex could be explain by a light-time effect caused by a third body in an eccentric orbit with a period of 58 years.
Key words: stars: : eclipsing / stars: : DK Cyg / stars: : V401 Cyg / stars: : AD Phe / stars: : Y Sex / stars: parameters
Some of the observations reported in this paper were obtained at the South Africa Astronomical Observatory, Sutherland, South Africa.
© European Southern Observatory (ESO), 2000