2004/07/20 by A. Derekas, L. L. Kiss, A. Udalski +3
Physics and Astronomy · #Astrophysics and Star Formation Studies #Solar and Space Plasma Dynamics #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1111/j.1365-2966.2004.08242.x
6 pages, 6 figures, accepted for publication in MNRAS
arxiv created 2004/07/20 · openalex publication_date 2004/10/20 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
A detailed light-curve analysis is presented for a first-overtone RR Lyrae star, MACHO* J050918.712−695015.31, based on MACHO and OGLE-III observations. As a foreground object of the Large Magellanic Cloud, it gives an extraordinary opportunity to study an almost continuous, 12-yr long data set of a relatively bright (V≈ 15.0 mag) RRc star with rapid period change. Cyclic period modulation is suggested by the O–C method, where the cycle length is about 8 yr. With the available unique data set, we could draw strong limits on other light-curve changes that may be associated with the period modulation. We could exclude both multiple periodicity and amplitude modulation unambiguously. Any theoretical model should reproduce the observed lack of photometric modulations. Simple arguments are also given for possible hydromagnetic effects.