The Blazhko Effect of AR Herculis

Abstract

V-band observations of the RR Lyrae star AR Her were obtained in 1992 and 1994–1995. During these years, AR Her continued to exhibit a strong Blazhko effect, showing light-curve variations more complex than pure amplitude modulation. The light curves of AR Her in 1992 and 1995 were modeled and compared with prior results. The light curve of AR Her is not a simple superposition of the light curves of an RRab and an RRc star. AR Her is therefore not, as has been suggested, a composite system made of an RRab and an RRc component. Coincident changes in primary and Blazhko period have been reported for some Blazhko variables. These period changes may possibly occur in AR Her, but stronger evidence for them has been seen in other stars. These changes suggest that the Blazhko period is not always equal to the rotation period of a star showing the Blazhko effect, in contradiction to recent rotator-pulsator models.