标题： 脉动恒星在OGLE数据库中P < 1天的傅里叶分解和频率分析。 II. 银河系核球中的多周期RR Lyr型变星 显示英文标题

标题： Fourier decomposition and frequency analysis of the pulsating stars with P < 1day in the OGLE database. II. Multiperiodic RR Lyrae variables in the Galactic Bulge

摘要： 我们展示了对OGLE-1样本中银河系晕RR Lyrae恒星的多周期脉动变星进行系统搜索的结果。 我们识别出一个“典型”的双模变星（RRd星），它在两个径向模式下脉动。 在38颗恒星中，我们检测到次级周期性非常接近主要脉动频率。 这种类型的多周期变星约占晕中RRab的23%和RRc的5%。 根据观测到的周期比为0.95-1.02，次级周期必须对应非径向振荡模式。 它们与主要（径向）脉动的叠加导致了长期振幅和相位调制，称为Blazhko效应。 Blazhko RRab变星在银河系晕中比在大麦哲伦星云中更常见。 而在RRd星的情况下则表现出相反的趋势。 发生率的差异很可能由两个星团的不同金属丰度引起。 我们讨论了OGLE-1 Blazhko星的脉动特性，并将它们与理论模型的预测进行比较。 我们认为，Shibahashi（2000）提出的倾斜磁场脉动模型无法解释观测结果，应被排除。 显示英文摘要

摘要： We present the results of a systematic search for multiperiodic pulsators among the Galactic Bulge RR Lyrae stars of the OGLE-1 sample. We identify one "canonical" double-mode variable (RRd star) pulsating in two radial modes. In 38 stars we detect secondary periodicities very close to the primary pulsation frequency. This type of multiperiodic variables constitute ~23% of RRab and ~5% of RRc population of the Bulge. With the observed period ratios of 0.95-1.02 the secondary periods must correspond to nonradial modes of oscillation. Their beating with the primary (radial) pulsation leads to a long-term amplitude and phase modulation, known as the Blazhko effect. The Blazhko RRab variables occur more frequently in the Galactic Bulge than in the LMC. The opposite tendency is seen in case of the RRd stars. The differences of incidence rates are most likely caused by different metallicity of the two populations. We discuss pulsation properties of the OGLE-1 Blazhko stars and compare them with predictions of theoretical models. We argue, that the oblique magnetic pulsator model of Shibahashi (2000) cannot account for the observations and should be ruled out.