论文标题
驼峰和颠簸:冲击对基本模式RR Lyrae星光的光学光曲线的影响
Humps and bumps: The effects of shocks on the optical light curves of fundamental-mode RR Lyrae stars
论文作者
论文摘要
我们介绍了迄今为止在1485 Rr〜lyrae恒星中进行的最扩展和均匀的研究,这是光学引力透镜实验(OGLE)观察到的银河系凸起中的。我们选择了具有优质光度法的非调节基本模式Rr〜lyrae恒星。使用一种自我开发的方法,我们确定了分阶段光曲线中主要和早期冲击特征的中心和优势。我们发现,驼峰和颠簸的位置与研究变量的脉动特性高度相关。具有明显主冲击的脉动器集中在周期振幅图的低振幅状态下,而具有强早期冲击的恒星具有平均水平和高于平均水平的脉动振幅。还观察到主要冲击和早期冲击与傅立叶系数之间的联系。在颜色标记图(CMD)中,我们看到恒星之间的分离强和弱冲击。具有明显的主冲击簇的变量靠近不稳定性带的基本红色边缘(IS),而具有强烈冲击的恒星倾向于在中心和IS基本蓝色边缘附近块。冲击及其性质的出现似乎与从研究恒星的周期变化率估计的进化方向无关。此外,在银河凸起中发现的两个主要的Oosterhoff组之间的周期变化率的差异表明,Oosterhoff I型的恒星位于零年龄的水平分支附近,而Oosterhoff II型变量正朝着不稳定条的基本红色边缘的路上,因此已经留下了零时代的水平水平分支。
We present the most extended and homogeneous study carried out so far of the main and early shocks in 1485 RR~Lyrae stars in the Galactic bulge observed by the Optical Gravitational Lensing Experiment (OGLE). We selected non-modulated fundamental-mode RR~Lyrae stars with good-quality photometry. Using a self-developed method, we determined the centers and strengths of main and early shock features in the phased light curves. We found that the position of both humps and bumps are highly correlated with the pulsation properties of the studied variables. Pulsators with a pronounced main shock are concentrated in the low-amplitude regime of the period-amplitude diagram, while stars with a strong early shock have average and above-average pulsation amplitudes. A connection between the main and early shocks and the Fourier coefficients is also observed. In the color-magnitude diagram (CMD), we see a separation between stars with strong and weak shocks. Variables with a pronounced main shock cluster close to the fundamental red edge of the instability strip (IS), while stars with a strong early shock tend to clump in the center and near the fundamental blue edge of the IS. The appearance of shocks and their properties seem independent of the direction of evolution estimated from the period change rate of the studied stars. In addition, the differences in the period change rate between the two main Oosterhoff groups found in the Galactic bulge suggest that stars of Oosterhoff type I are located close to the zero-age horizontal branch while Oosterhoff type II variables are on their way toward the fundamental red edge of the instability strip, thus having already left the zero-age horizontal branch.