天琴座RR型变星的Blazhko效应

The Blazhko Effect of RR Lyrae Variables

Blazhko效应,即一部分天琴座RR型变星的光变曲线的振幅和/或相位调制,早在一个世纪之前就被发现了,但是其中的物理机制还是未知。自从发现Blazhko效应以来,天文学家已经对该效应做了大量的观测和理论研究。需要特别提到的是,借助空间望远镜,最近的研究已经发现大量Blazhko效应的新特性。全面综述最新的观测和理论结果,主要集中于过去十几年研究天琴座RR型变星及Blazhko效应的工作,以期对以后研究Blazhko效应有所帮助。

The Blazhko effect, the amplitude and/or phase modulation of the light curves of a fraction of the RR Lyrae variables, was discovered more than one century ago. Extensive observational and theoretical studies of the Blazhko effect have been done since then, yet the physical reason of the effect is still unknown. Specifically, with the help of high precision and long-time coverage data from space telescopes such as Kepler and CoRoT telescopes,a lot of new observational properties of the Blazhko effect have been revealed. Statistics on the incidence rate of the Blazhko stars among the RR Lyrae variables show that the Blazhko effect is quite common. The Blazhko modulation itself is not periodic or regular in many Blazhko RR Lyrae stars, which is in contradiction with traditional definition of the effect. Physical parameters of the Blazhko variables vary among different Blazhko cycles.Moreover, RR Lyrae variables might not be purely radial pulsating stars as non-radial modes are suspected in several Blazhko stars. We first summarize the observational progress in the Blazhko effect of the RR Lyrae variables over the past decades, then we review the existing theoretical models in the literature. We conclude that none of the current models can explain all the observational properties. As such, theoretic studies of the Blazhko effect deserve much attention.