AAVSO: American Association of Variable Star Observers

CCD Photometry, Period Analysis, and Evolutionary Status of the Pulsating Variable V544 Andromedae

Volume 47 number 2 (2019)

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Kevin B. Alton
UnderOak and Desert Bloom Observatories, 70 Summit Ave, Cedar Knolls, NJ 07927; kbalton@optonline.net

Abstract

Multi-color (BVRc) CCD-derived photometric data were acquired from V544 And, a pulsating variable presently classified as an SX Phe-type subdwarf system. Deconvolution of time-series light curve (LC) data was accomplished using discrete Fourier transformation and revealed a mean fundamental mode (f0) of oscillation at 9.352 dā€“1 along with five other partial harmonics (2f0ā€“6f0). No other statistically significant frequency shared by all bandpasses was resolved. Potential secular period changes were evaluated using four new times-of-maximum (ToMax) light produced from the present study along with other values reported in the literature. In addition, photometric data collected during the SuperWASP (2006ā€“2007) survey combined with CCD-derived V-mag data acquired from the AAVSO archives produced twenty-nine more ToMax measurements. Corresponding residuals from the observed minus calculated values indicate very little change in the primary pulsation period since 2004. The evolutionary status, age, and physical nature of V544 And were investigated using the PAdova and TRieste Stellar Evolution Code (parsec) for generating stellar tracks and isochrones. At this time, the weight of evidence points to a HADS rather than an SX Phe-type pulsating star.