• RR Lyrae stars;
  • stars: horizontal-branch;
  • stars: individual (TV Boo);
  • stars: oscillations;
  • techniques: photometric


We present the analysis of the multicolour CCD observations in the 2010 season of the Blazhko RRc star TV Boo. TV Boo shows a complex Blazhko modulation dominated by two independent modulations with periods Pfm1 = 9.74 d and Pfm2 = 21.43 d. Both modulation components appear in the frequency spectra as multiplet structures around the harmonics of the pulsation. The positive value of the asymmetry parameter (Q = +0.51) of the primary modulation suggests that it is similar in its character to the Blazhko-effect of most of the modulated RRab stars. Interestingly, the secondary, lower-amplitude modulation exhibits a negative asymmetry parameter (Q = −0.22), which is an unusually low value when compared to the Blazhko-modulated RRab stars. Apart from the two modulation frequencies, the spectra also show an additional frequency f’ and its linear combinations with the pulsation and the primary modulation f1 + f’ and f1f’fm1. We conclude that the additional frequency most probably belongs to a non-radial mode (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)