Photometric study of an SX phoenicis variable in the galactic halo

• Published in: Astronomy reports Vol. 51; no. 8; pp. 624 - 641
• Main Authors: KIM, C, JEON, J.-B, KIM, S.-L, YUSHCHENKO, A. V
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 01-08-2007; Springer Nature B.V
• Subjects: Astronomy; Earth, ocean, space; Exact sciences and technology; Frequency analysis; Stars & galaxies; Galactic halos; Milky Way
• ISSN: 1063-7729; 1562-6881
• DOI: 10.1134/S1063772907080033

We have studied the relatively recently discovered object 2-7-0122, with a V magnitude of 17, and have confirmed that it is an SX Phe variable star. Our photometry at the 1.8 m telescope of the Boyhunsan Observatory and the 1.0 m telescope of the Mount Lemon Observatory has enabled us to refine the photometric elements and to perform a frequency analysis of the light curve. We demonstrate the presence of two close frequencies, f 1 = 24.6539 cycles/day and f 2 = 24.8173 cycles/day, one of them possibly non-radial, and of several combinational frequencies. The star's metallicity is at least two orders of magnitude lower than that of the Sun, making the star the most metal-poor SX Phe object in the Galactic field. We confirm variability of another star in the field of view, and have determined its light elements and its possible variability type (RRc).