Department of Physics and Astronomy: Publications and Other Research
Date of this Version
February 1998
Abstract
The General Catalogue of Variable Stars (Kholopov 1985) lists V719 Her as a probable type c RR Lyrae star with a period of 0.336 days. In the remarks, it is noted that another possibility is that V719 Her is a W UMa eclipsing binary with a period of .67 days. Schmidt (1991; 1993) obtained 15 light curve points in 1989-91 and concluded that V719 Her is indeed a W UMa star but with a period of .400995 days. Goderya, Leung and Schmidt (1996; 1997) subsequently obtained extensive photometry in 1993 which pro¬vided timings for five minima over an interval of 78 days. Combining these data with the 1989-91 observations yielded a period of 0.400983 days. However, the resulting O-C plot showed a systematic trend in the 1993 data which suggested a shorter period. Goderya et al. interpreted this in terms of a period decrease of 0.54 seconds per year which is unusu¬ally large for a W UMa star.
In an attempt to verify the large period change, further VR photometry was conducted on four nights in 1995 and 16 nights in 1997. The observations were all obtained with the CCD camera on the Behlen Observatory 0.76-m telescope. The observation and reduction techniques were the same as described by Schmidt (1991). We used the same comparison stars as Goderya, Leung and Schmidt (1996) but redetermined the mean magnitudes and colors using a total of twelve photometric nights. The values are given in Table 1 and are accurate to better than 0.01 magnitudes.
More than 200 new light curve points were obtained. The individual observations have been placed in the IAU Archives of Unpublished Variable Star Observations (file number 333E) or they can be obtained from the author.
Comments
Published in the IAU Information Bulletin on Variable Stars No. 4552 (1998). Used by permission. The IBVS is open-access and available online at http://www.konkoly.hu/IBVS/IBVS.html