Variable Stars in Palomar 13; an Evaporating Globular Cluster

We present new CCD VI photometry of the globular cluster Pal 13. Fourier decomposition of the light curves of RRab stars lead to estimations of [Fe/H]_ZW = -1.65±0.15, and a distance to the cluster of 23.67±0.57 kpc. A 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 and one BL Her star. The Gaia-DR2 proper motions of member stars in Pal 13 show a significant scatter, consistent with the scenario of the cluster being tidally stripped.