Abstract

ABDEL-SABOUR, Mohamed; SHOKRY, Ahmed  and  IBRAHIM, Ahmed. Analysis of a short periodic pulsator: SX phoenicis star XX Cyg. Rev. mex. astron. astrofis [online]. 2020, vol.56, n.2, pp.287-294.  Epub Mar 24, 2021. ISSN 0185-1101.  https://doi.org/10.22201/ia.01851101p.2020.56.02.10.

Photometric observations were made of the SX Phoenicis star XX Cyg between September and October 2019, using the 1.88-m Kottamia reflector telescope in Egypt. We used 340 CCD observations with blue-visible-red (BVR) filters to derive light curves. In addition, we obtained 9540 visual magnitudes for XX Cyg from the literature to prepare an observed-minus-calculated (O-C) diagram. 85 new times of maximum for XX Cyg are presented. We did not detect a bump in the descending portion of the light curve of maximum light for XX Cyg. However, we did detect a secular bump in the phased light curves, which changes with phase in some SuperWASP observations. We found the change in period of XX Cyg to be dP/dt = 15.5×10−5 s/yr, with its amplitude decreasing at a rate of 0.7 mmag/year. Stellar parameters of XX Cyg and its position in the instability strip of the Hertzsprung Russell stellar evolution diagram are presented.