LCs of the RR Lyrae stars V350 Lyr & KIC 7021124

Space data seem to indicate a clear trend that, 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 (V350Lyr and KIC7021124), 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 a small amplitude (but significant) Blazhko effect for both stars by using the resulting light curves and O-C diagrams. This finding strengthens the apparent connection between the Blazhko effect and the excitation of additional modes.