论文标题
对M56中变量星及其颜色幅度图结构的新访问
A new visit to the variable stars in M56 and its colour magnitude diagram structure
论文作者
论文摘要
我们提供了一项$ VI $ CCD光度研究和球状群集M56（NGC 6779）的成员分析。这产生了现场恒星的污染CMD，从而使理论等同源更好地对抗。零年龄水平分支（ZAHB）和ZAHB后进化轨道。发布He-Flash进化模型，其核心质量为0.5 m $ _ \ odot $，信封为0.04-0.18 m $ _ $ _ \ odot $，覆盖完整的水平分支。具有总质量$ \ sim $ 0.68 m $ _ \ odot $的模型解释了RR Lyre，而质量$ \ sim $ \ sim $ 0.56 m $ _ $ _ \ odot $和非常微妙的信封的模型解释了Pop II Cepheids，带有HB蓝色尾巴的祖细胞。 ％使用平均$（V-I）$在最小颜色曲线的RRAB星星中，我们得出了$ e（B-V）$ = 0.26 $ \ pm $ 0.02的红色值的值。基于单个群集成员RRC星的$ V $光曲线的傅立叶分解，我们确定了$ \ rm [fe/h] _ {zw} $ = -1.96 $ \ pm $ 0.09的金属度。几种独立的距离确定方法导致平均距离$ \ big <d \ big> $ = 9.4 $ \ pm $ 0.4 kpc。最后，我们报告了5个新变量：1 SX PHE，3 EB和1 RRC。
We present a $VI$ CCD photometric study and a membership analysis of the globular cluster M56 (NGC 6779). This produced a decontaminated CMD from field stars, which enabled a better confrontation with theoretical isochrones; Zero-Age Horizontal Branches (ZAHB) and post-ZAHB evolutionary tracks. Post He-flash evolutionary models with a He-core mass of 0.5 M$_\odot$ and envelopes of 0.04 - 0.18 M$_\odot$, cover the complete Horizontal Branch. Models with total mass $\sim$ 0.68 M$_\odot$ explain the RR Lyrae, while those with a mass $\sim$ 0.56 M$_\odot$ and a very subtle envelope, explain the Pop II cepheids with a progenitor in the blue tail of the HB. %Using the mean $(V-I)$ at minimum color curve for the RRab stars, we derived a value for the reddening of $E(B-V)$ = 0.26 $\pm$ 0.02. Based on the Fourier decomposition of the $V$ light curve of a single cluster member RRc star, we determined a metallicity of $\rm [Fe/H]_{ ZW}$ = -1.96 $\pm$ 0.09. Several independent distance determination approaches lead to a mean distance to M56 of $\big< d \big>$ = 9.4 $\pm$ 0.4 kpc. Finally, we report 5 new variables: 1 SX Phe, 3 EB, and 1 RRc.
