The Blazhko effect and additional excited modes in RR Lyrae stars

Abstract

Recent photometric space missions, such as CoRoT and Kepler revealed that many RR Lyrae stars pulsate -- beyond their main radial pulsation mode -- in low amplitude modes. Space data seem to indicate a clear trend, namely overtone (RRc) stars and modulated fundamental (RRab) RR Lyrae stars ubiquitously show additional modes, while non-Blazhko RRab stars never do. Two Kepler stars (V350 Lyr and KIC 7021124), however, apparently seemed to break this rule: they were classified as non-Blazhko RRab stars showing additional modes. We processed Kepler pixel photometric data of these stars. We detected small amplitude, but significant Blazhko effect for both stars by using the resulted light curves and O$-$C diagrams. This finding strengthens the apparent connection between the Blazhko effect and the excitation of additional modes. In addition, it yields a potential tool for detecting Blazhko stars through the additional frequency patterns even if we have only short but accurate time series observations. V350 Lyr shows the smallest amplitude multiperiodic Blazhko effect ever detected.

6 pages, 4 figures and 2 tables. Accepted for publication in ApJ Letters

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Cited by in corpus (9)

• The Kepler Cepheid V1154 Cyg revisited: light curve modulation and detection of granulation
• First results on RR Lyrae stars with the TESS space telescope: untangling the connections between mode content, colors and distances
• Revisiting the Kepler non-Blazhko RR Lyrae sample: Cycle-to-cyle variations and additional modes
• Finest light curve details, physical parameters, and period fluctuations of CoRoT RR Lyrae stars
• On the connection between almost periodic functions and Blazhko light curves
• Two Different Weak Modulations in ab-type RR Lyrae Variable V838 Cyg, and Potential Influence of Metal Abundance on Blazhko Modulation
• Digging Deeper for RR Lyrae Stars with Low Modulation Amplitudes
• Atmospheric dynamics and shock waves in RR Lyr -- I. The three H$\alpha$ emissions
• Kepler Pixel Project -- background RR Lyrae stars in the primary Kepler mission field of view