2024/01/04 by Luis Lomelí-Núñez, Y. D. Mayya, Lomelí-Núñez, Luis +19 · 1 citation
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #Stellar, planetary, and galactic studies
paper · pdf · doi:10.48550/arxiv.2401.02519
openalex publication_date 2024/01/04 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We here present the results of an analysis of the optical spectroscopy of 42 globular cluster (GC) candidates in the nearby spiral galaxy M81 (3.61~Mpc). The spectra were obtained using the long-slit and MOS modes of the OSIRIS instrument at the 10.4~m Gran Telescopio Canarias (GTC) at a spectral resolution of ∼1000. We used the classical Hβ vs [MgFe]' index diagram to separate genuine old GCs from clusters younger than 3 Gyr. Of the 30 spectra with continuum signal-to-noise ratio >10, we confirm 17 objects to be classical GCs (age >10~Gyr, -1.4<[Fe/H]<-0.4), with the remaining 13 being intermediate-age clusters (1-7.5~Gyr). We combined age and metallicity data of other nearby spiral galaxies (\lesssim18~Mpc) obtained using similar methodology like the one we have used here to understand the origin of GCs in spiral galaxies in the cosmological context. We find that the metal-poor ([Fe/H]<-1) GCs continued to form up to 6~Gyr after the first GCs were formed, with all younger systems (age <8~Gyr) being metal-rich.