Properties of Stellar Populations of Eight Galactic Global Clusters with Low Central Surface Brightness

This paper presents the results of the analysis of the integrated-light spectra of eight Galactic globular clusters with a relatively low luminosity and stellar density: Palomar 1, Palomar 2, Palomar 10, Palomar 13, Palomar 14, NGC 6426, NGC 6535, and NGC 6749. The absorption spectral indices in the Lick system were measured in their spectra, as well as in the spectra of bright clusters: NGC 7006, NGC 6229, NGC 6779, NGC 6205, NGC 6341, and NGC 2419. The age, metallicity, and approximate abundance of the alpha-process elements were determined for eight objects under study. The material of the study was the archival observational data of the 1.93-m telescope of the Haute-Provence Observatory. For seven out of eight objects, galactic analogs with close values of the Lick indices within the limits of their determination errors were found. The coincidence of the Lick indices implies the similarity of age and chemical composition. The available literature data confirm our conclusions regarding the similarity of the properties of the clusters' stellar populations. According to the literature data on the spatial position and motion of objects, the objects of study turned out to belong, as a rule, to the same subsystems of the Galaxy as their analogs. No globular clusters with a complete set of Lick indices similar to those of Palomar 1 were found, which supports the literature conclusions about its possible extragalactic origin. Our photometry of stars in the VLT images and the Gaia DR3 data allowed us to estimate the metallicity, age, color excess, and distance for Palomar 10. The Gaia DR3 data for NGC 6426 were analyzed.