The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. XX. Ages of Single and Multiple Stellar Populations in Seven Bulge Globular Clusters

Journal
Date Issued
2020
Author(s)
Oliveira, RAP
•
Souza, SO
•
Kerber, LO
•
Barbuy, B
•
Ortolani, S
•
Piotto, G
•
Nardiello, D
•
Perez-Villegas, A
•
Maia, FFS
•
Bica, E
•
•
D'Antona, F
•
Lagioia, EP
•
Libralato, M
•
Milone, AP
•
Anderson, J
•
Aparicio, A
•
•
Brown, TM
•
King, IR
•
Marino, AF
•
•
Renzini, A
•
Sarajedini, A
•
van der Marel, R
•
Vesperini, E
DOI
Abstract
In the present work we analyzed seven globular clusters (GCs) selected from their location in the Galactic bulge and with metallicity values in the range -1.30 ≲ [Fe/H] ≲ -0.50. The aim of this work is first to derive cluster ages assuming single stellar populations and second to identify the stars from first (1G) and second generations (2G) from the main sequence, subgiant, and red giant branches, and to derive their age differences. Based on a combination of UV and optical filters used in this project, we apply the Gaussian mixture models to distinguish the multiple stellar populations. Applying statistical isochrone fitting, we derive self-consistent ages, distances, metallicities, and reddening values for the sample clusters. An average age of 12.3 ? 0.4 Gyr was obtained both using DSED and BaSTI (accounting atomic diffusion effects) isochrones, without a clear distinction between the moderately metal-poor and the more metal-rich bulge clusters, except for NGC 6717 and the inner halo NGC 6362 with ∼13.5 Gyr. We derived a weighted mean age difference between the multiple populations hosted by each GC of 41 ? 170 Myr adopting canonical He abundances; whereas for higher He in 2G stars, this difference reduces to 17 ? 170 Myr, but with individual uncertainties of 500 Myr.
Volume
891
Issue
1
Start page
37
Uri
Url
Issn Identifier
0004-637X
Ads BibCode
2020ApJ...891...37O
Rights
restricted
File(s)
Loading...
Thumbnail Image
Name

Oliveira_2020_ApJ_891_37-2.pdf

Description
[Administrators only]
Size

9.28 MB

Format

Adobe PDF

Checksum (MD5)

4a65e31f36865cfd3d1d67dc96e57c6f

Loading...
Thumbnail Image
Name

2001.08611.pdf

Size

4.94 MB

Format

Adobe PDF

Checksum (MD5)

bdd0fc10be04816174dfe48ce112f88f