1. Ages and metallicities of globular clusters in M81 using GTC/OSIRIS spectra
- Author
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Lomelí-Núñez, Luis, Mayya, Y. D., Rodríguez-Merino, L. H., Ovando, P. A., Alzate, Jairo A., Rosa-González, D., Cuevas-Otahola, B., Bruzual, Gustavo, Cortesi, Arianna, Gómez-González, V. M. A, and Escudero, Carlos G. more...
- Subjects
Astrophysics - Astrophysics of Galaxies - Abstract
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 $\sim$1000. We used the classical H$\beta$ 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., Comment: 16 pages, 13 figures, 8 tables; Accepted for publication in MNRAS more...
- Published
- 2024