2004/01/20 by P. Pietrukowicz, Pawel Pietrukowicz, Pietrukowicz, Pawel +3
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics (astro-ph) #Astrophysics and Star Formation Studies #FOS: Physical sciences #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0401385
10 pages with 4 figures, already published in Acta Astronomica vol. 53, p. 371
arxiv created 2004/01/20 · openalex publication_date 2004/01/20 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Time-series data taken with the Hubble Space Telescope of three fields\ncovering the central part of the globular cluster M22 have been analyzed in\nsearch of variable objects. We report identification of 11 periodic variables\nof which 8 are new discoveries. The sample includes 5 certain contact binaries\nas well as 1 SX Phe star. Two objects with periods longer than 1 day are\npreliminarily classified as either spotted variables of BY Dra type or\nellipsoidal variables. The most unusual of the identified variables, M22V11,\nhas IC=19.9 and is located far to the red of the main sequence in the cluster\ncolor-magnitude diagram. It shows variability with a period as short as P=0.066\ndays or alternatively with P=0.132 days. We propose that it may be an\nellipsoidal variable harboring a degenerate component.\n