Chemical composition and ages of four globular clusters in M31 from the analysis of their integrated-light spectra

Abstract

We compare the results on the chemical composition of four globular clusters (GCs) in M31 (Bol 6, Bol 20, Bol 45, and Bol 50) (Maricheva M. 2021). Study of integrated spectra of four globular clusters in M31. Astrophys. Bull. 76:389-404. doi: https://doi.org/10.1134/S199034132104009X) to the available literature data on integrated-light spectroscopy of GCs with similar ages and chemical abundances in our Galaxy and M31 and on the chemical abundances of stars in two galaxies. The clusters and their literature analogues are of moderate metallicity -1.1<[Fe/H]<-0.75 dex and old (10 Gyr). Mg, Ca, and C abundances of four GCs are higher than literature estimates for the GCs in M31 with [Fe/H]~-1 dex obtained using high-resolution integrated-light spectroscopy methods. Using literature data, we did not find complete analogues for the studied clusters in our Galaxy and M31 in terms of age, helium mass fraction (Y), and chemical composition. The alpha-element abundances in four clusters are about 0.2 dex higher than the average for stars in the Galactic field at [Fe/H]~-1 dex. We suggest that these and M. Maricheva's (Maricheva M. 2021) findings about lower metallicities of the studied objects than the average metallicity of red giants in the M31 halo and about the abundances of alpha-process elements in them corresponding to the average value for stars in the M31 inner halo likely indicate that the star formation process in the vicinity of M31 at the time of our sample cluster formation was complex with the inflow of fresh gas from the intergalactic medium and violent star forming events associated with SNe II bursts.

Published in the Open Astronomy jornal, De Gruyter Open Access (Special Issue: Modern Stellar Astronomy)

References in corpus (11)

• Galactic chemical evolution: Carbon through Zinc
• The ACS Survey of Galactic Globular Clusters. I. Overview and Clusters Without Previous HST Photometry
• Scaled solar tracks and isochrones in a large region of the Z-Y plane I. From the ZAMS to the TP-AGB end for 0.15 - 2.5 Mo stars
• An updated survey of globular clusters in M31. II Newly discovered bright and remote clusters
• The Detailed Chemical Properties of M31 Star Clusters I. Fe, Alpha and Light Elements
• Infrared High-Resolution Integrated Light Spectral Analyses of M31 Globular Clusters from APOGEE
• Excess of Ca (and Sc) produced in globular cluster multiple populations: a first census in 77 Galactic globular clusters
• Elemental Abundances in M31: Iron and Alpha Element Abundances in M31's Outer Halo
• Hubble Space Telescope imaging of the extremely metal-poor globular cluster EXT8 in Messier 31
• Analysis of integrated-light spectra of Galactic globular clusters
• Study of Integrated Spectra of Four Globular Clusters in M31