ON THE MODULATION OF RR LYRAE STARS IN THE GLOBULAR CLUSTER M3

Journal Article · Wed Dec 10 04:00:00 EST 2014 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/797/1/L3· OSTI ID:22364882

Jurcsik, J.; Smitola, P.; Nuspl, J. ^[1]

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1. Konkoly Observatory, P.O. Box 67, H-1525 Budapest (Hungary)

New, extended time-series photometry of M3 RR Lyrae stars has revealed that 4 of the 10 double-mode stars show large-amplitude Blazhko modulation of both radial modes. The first, detailed analysis of the peculiar behavior of the unique, Blazhko RRd stars is given. While the P1/P0 period ratio is normal, and the overtone mode is dominant in the other RRd stars of the cluster, the period ratio is anomalous and the fundamental mode has a larger (or similar) mean amplitude than the overtone has in Blazhko RRd stars. The modulations of the fundamental and overtone modes are synchronized only in one of the Blazhko RRd stars. No evidence of any connection between the modulations of the modes in the other three stars is found. The Blazhko modulation accounts, at least partly, for the previously reported amplitude and period changes of these stars. Contrary to the ∼50% Blazhko statistics of RRab and RRd stars, Blazhko modulation occurs only in 10% of the overtone variables in M3. Four of the five Blazhko RRc stars are bright, evolved objects, and one has a period and brightness similar to those of Blazhko RRd stars. The regions of the instability strip with high and low occurrence rates of the Blazhko modulation overlap with the regions populated by first- and second-generation stars according to theoretical and observational studies, raising up the possibility that the Blazhko modulation occurs preferentially in first-generation RR Lyrae stars.

• OSTI ID: 22364882
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 1 Vol. 797; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
AMPLITUDES
BRIGHTNESS
MODULATION
OSCILLATIONS
PHOTOMETRY
STAR CLUSTERS
STATISTICS
VARIABLE STARS