CCD observations and period change of the type ab RR Lyrae star DV Monстатья
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Дата последнего поиска статьи во внешних источниках: 24 июля 2019 г.
Аннотация:We took a total of 635 B-, V -, and I c -band CCD frames for the RRab Lyr type variableDVMon, which has a close bright visual companion with a separation of about 1.9 ?? . Observations weremade with the 76-cm telescope of the South African Astronomical Observatory (SAAO, South Africa)using SBIG CCD ST-10XME. For the first time, we obtained reliable separate PSF-photometry ofboth stars and determined their coordinates. We used all available data to construct the O − C diagramspanning a 110-year long time interval, which allowed us to reveal at least three sudden changes of thepulsation period around JD 2438000, 2453500, and 2456500. Our high resolution echelle spectra with theSouthern African Large Telescope (SALT) showed that DVMon belongs to type ab RR Lyrae variables ofthe Galactic thick disk.