On the incidence rate of first overtone Blazhko stars in the Large Magellanic Cloud

Abstract

By using the full span of multicolor data on a representative sample of first overtone RR Lyrae stars in the Large Magellanic Cloud (LMC) we revisit the problem of the incidence rate of the amplitude/phase-modulated (Blazhko) stars. Multicolor data, obtained by the MAssive Compact Halo Objects (MACHO) project, are utilized through a periodogram averaging method. This enables us to increase the number of detected multiperiodic variables by 18% relative to the number obtained by the analysis of the best single color data. We also test the maximum modulation period detectable in the present dataset. We find that variables showing amplitude/phase modulations with periods close to the total time span can still be clearly separated from the class of stars showing period changes. This larger limit on the modulation period, the more efficient data analysis and the longer time span lead to a substantial increase in the incidence rate of the Blazhko stars in comparison with earlier results. We find altogether 99 first overtone Blazhko stars in the full sample of 1332 stars, implying an incidence rate of 7.5%. Although this rate is nearly twice of the one derived earlier, it is still significantly lower than that of the fundamental mode stars in the LMC. The by-products of the analysis (e.g., star-by-star comments, distribution functions of various quantities) are also presented.

arXiv comment12 pages, 10 figures, 9 tables, to appear in Astronomy and Astrophysics

References in corpus (8)

• A box-fitting algorithm in the search for periodic transits
• Calibration of the MACHO Photometry Database
• The MACHO Project LMC Variable Star Inventory. IX. Frequency Analysis of the First Overtone RR Lyrae Stars and the Indication for Nonradial Pulsations
• The MACHO Project Large Magellanic Cloud variable star inventory. XI. Frequency analysis of the fundamental mode RR Lyrae stars
• The MACHO Project 9 Million Star Color-Magnitude Diagram of the Large Magellanic Cloud
• Fourier decomposition and frequency analysis of the pulsating stars with P < 1day in the OGLE database. II. Multiperiodic RR Lyrae variables in the Galactic Bulge
• The MACHO Project Large Magellanic Cloud Variable Star Inventory. XIII. Fourier Parameters for the First Overtone RR Lyrae Variables and the LMC Distance
• Iron abundances derived from RR Lyrae light curves and low-dispersion spectroscopy

Cited by in corpus (15)

• Flavours of variability: 29 RR Lyrae stars observed with Kepler
• Kepler photometry of RRc stars: peculiar double-mode pulsations and period doubling
• Frequency analysis of Cepheids in the Large Magellanic Cloud. New types of classical Cepheid pulsators
• An RR Lyrae family portrait: 33 stars observed in Pisces with K2-E2
• Blazhko-type modulation in the double-mode RR Lyrae stars of the OGLE Galactic bulge collection
• Double-mode radial-non-radial RR Lyrae stars in the OGLE photometry of the Galactic bulge
• Blazhko effect in the Galactic bulge fundamental mode RR~Lyrae stars I: Incidence rate and differences between modulated and non-modulated stars
• Study of Globular Cluster M53: new variables, distance, metallicity
• The SERMON project: 48 new field Blazhko stars and an investigation of modulation-period distribution
• Pulsational and evolutionary analysis of the double-mode RR Lyrae star BS Com
• Application of the Trend Filtering Algorithm on the MACHO Database
• Analysis of a selected sample of RR Lyrae stars in LMC from OGLE III
• Five colour photometry of the RRd star V372 Ser
• The double-mode RR Lyrae variable BS Com
• The Blazhko modulation of TV Boo in 2010