2002/11/13 by P. Moskalik, E. Poretti · 2 citations
Physics and Astronomy · #Amplitude #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Astrophysics and Star Formation Studies #Biology #Bulge #Frequency analysis #Globular cluster #Metallicity #Oscillation (cell signaling) #Physics #Population #RR Lyrae variable #Stars #Stellar, planetary, and galactic studies #Variable star #astro-ph
paper · pdf · doi:10.1051/0004-6361:20021595
published as Astron.Astrophys. 398 (2003) 213-222 · 11 pages, 8 figures, accepted for publication in Astronomy & Astrophysics
arxiv created 2002/11/13 · openalex publication_date 2002/11/13 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present the results of a systematic search for multiperiodic pulsators among the Galactic Bulge RR Lyrae stars of the OGLE-1 sample. We identify one "canonical" double-mode variable (RRd star) pulsating in two radial modes. In 38 stars we detect secondary periodicities very close to the primary pulsation frequency. This type of multiperiodic variables constitute ~23% of RRab and ~5% of RRc population of the Bulge. With the observed period ratios of 0.95-1.02 the secondary periods must correspond to nonradial modes of oscillation. Their beating with the primary (radial) pulsation leads to a long-term amplitude and phase modulation, known as the Blazhko effect. The Blazhko RRab variables occur more frequently in the Galactic Bulge than in the LMC. The opposite tendency is seen in case of the RRd stars. The differences of incidence rates are most likely caused by different metallicity of the two populations. We discuss pulsation properties of the OGLE-1 Blazhko stars and compare them with predictions of theoretical models. We argue, that the oblique magnetic pulsator model of Shibahashi (2000) cannot account for the observations and should be ruled out.