The Hubble Space Telescope UV Legacy Survey of galactic globular clusters - II. The seven stellar populations of NGC 7089 (M2)

Journal
Date Issued
2015
Author(s)
Milone, A. P.
•
•
Piotto, G.
•
•
Anderson, J.
•
Renzini, A.
•
King, I. R.
•
Bellini, A.
•
Brown, T. M.
•
•
D'Antona, F.
•
Jerjen, H.
•
Nardiello, D.
•
Salaris, M.
•
Marel, R. P. van der
•
Vesperini, E.
•
Yong, D.
•
Aparicio, A.
•
Sarajedini, A.
•
Zoccali, M.
DOI
Description
Support for Hubble Space Telescope proposal GO-13297 was provided by NASA through grants from STScI, which is operated by AURA, Inc., under NASA contract NAS 5-26555. APM and HJ acknowledge support by the Australian Research Council through Discovery Project grant DP120100475. MZ acknowledges support by Proyecto Fondecyt Regular 1110393, by the BASAL Center for Astrophysics and Associated Technologies PFB-06, and by Project IC120009 ‘Millennium Institute of Astrophysics (MAS)’ of Iniciativa Científica Milenio by the Chilean Ministry of Economy, Development and Tourism.
Abstract
We present high-precision multiband photometry for the globular cluster (GC) M2. We combine the analysis of the photometric data obtained from the Hubble Space Telescope UV Legacy Survey of Galactic GCs GO-13297, with chemical abundances by Yong et al., and compare the photometry with models in order to analyse the multiple stellar sequences we identified in the colour-magnitude diagram. We find three main stellar components, composed of metal-poor, metal-intermediate, and metal-rich stars (hereafter referred to as population A, B, and C, respectively). The components A and B include stars with different s-process element abundances. They host six sub-populations with different light-element abundances, and exhibit an internal variation in helium up to ∆Y ̃ 0.07 dex. In contrast with M22, another cluster characterized by the presence of populations with different metallicities, M2 contains a third stellar component, C, which shows neither evidence for sub-populations nor an internal spread in light-elements. Population C does not exhibit the typical photometric signatures that are associated with abundance variations of light elements produced by hydrogen burning at hot temperatures. We compare M2 with other GCs with intrinsic heavy-element variations and conclude that M2 resembles M22, but it includes an additional stellar component that makes it more similar to the central region of the Sagittarius galaxy, which hosts a GC (M54) and the nucleus of the Sagittarius galaxy itself.
Volume
447
Issue
1
Start page
927
Uri
Url
Issn Identifier
0035-8711
Ads BibCode
2015MNRAS.447..927M
Rights
open.access
File(s)
Loading...
Thumbnail Image
Name

stu2446.pdf

Description
PDF editoriale
Size

3.8 MB

Format

Adobe PDF

Checksum (MD5)

8af52dbe64822f75144f2ffe6b029e71