标题： Palomar 13中的变星；一个蒸发的球状星团 显示英文标题

标题： Variable stars in Palomar 13; an evaporating globular cluster

摘要： 我们展示了距离遥远的球状星团Pal 13的新CCD $VI$ 光度测量数据。对三个属于该星团的RRab型变星光变曲线的傅里叶分解得到了[Fe/H]=-1.65和距离为23.67$\pm$0.57千秒差距的结果。对于RRab型变星，在光度和颜色最小相位附近的数据给出了 $E(B-V)$=0.104 $\pm$ 0.001的估计值。使用可能的成员星构建的 $V/(V-I)$ 颜色-亮度图与上述参数一致，并且年龄为12十亿年。 在我们图像视场内变星搜索显示了一个红巨星成员和三个可能非成员的变异性；两个RRab型变星和一个W Virginis型变星或CW型变星。Pal 13中成员星的GAIA自行显示出显著的分散，这与星团被潮汐剥离的情景一致。 显示英文摘要

摘要： We present new CCD $VI$ photometry of the distant globular cluster Pal 13. Fourier decomposition of the light curves of the three cluster member RRab stars lead to estimations of [Fe/H]=-1.65, and a distance of 23.67$\pm$0.57 kpc. Light and colour near minimum phases for RRab stars leads to an estimate of $E(B-V)$=0.104 $\pm$ 0.001. A $V/(V-I)$ colour-magnitude diagram, built exclusively with likely star members, shows consistency with the above parameters and an age of 12 Gyrs. A search of variable stars in the field of view of our images revealed the variability of a red giant cluster member and of three probably non-member stars; two RRab stars and one W Virginis star or CW. The GAIA proper motions of member stars in Pal 13 show a significant scatter, consistent with the scenario of the cluster being tidally stripped.