MULTIPLE POPULATIONS IN THE OLD AND MASSIVE SMALL MAGELLANIC CLOUD GLOBULAR CLUSTER NGC 121

Journal Article · Sat Oct 01 04:00:00 EDT 2016 · Astrophysical Journal

DOI:https://doi.org/10.3847/0004-637X/829/2/77· OSTI ID:22667396

Dalessandro, E.; Lapenna, E.; Mucciarelli, A.; Ferraro, F. R.; Lanzoni, B. ^[1]; Origlia, L. ^[2]

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1. Dipartimento di Fisica and Astronomia, Università degli Studi di Bologna, viale Berti Pichat 6/2, I–40127, Bologna (Italy)
2. INAF—Osservatorio Astronomico di Bologna, via Ranzani 1, I-40127, Bologna (Italy)

We used a combination of optical and near-UV Hubble Space Telescope photometry and FLAMES/ESO-VLT high-resolution spectroscopy to characterize the stellar content of the old and massive globular cluster (GC) NGC 121 in the Small Magellanic Cloud (SMC). We report on the detection of multiple stellar populations, the first case in the SMC stellar cluster system. This result enforces the emerging scenario in which the presence of multiple stellar populations is a distinctive-feature of old and massive GCs regardless of the environment, as far as the light-element distribution is concerned. We find that second-generation (SG) stars are more centrally concentrated than first-generation (FG) ones. More interestingly, at odds with what is typically observed in Galactic GCs, we find that NGC 121 is the only cluster so far to be dominated by FG stars that account for more than 65% of the total cluster mass. In the framework where GCs were born with 90%–95% of FG stars, this observational finding would suggest that either NGC 121 experienced a milder stellar mass-loss with respect to Galactic GCs or it formed a smaller fraction of SG stars.

• OSTI ID: 22667396
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 829; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABUNDANCE
DETECTION
DISTRIBUTION
MAGELLANIC CLOUDS
MASS TRANSFER
PHOTOMETRY
RESOLUTION
SPACE
STAR CLUSTERS
STARS
STELLAR WINDS
TELESCOPES
VISIBLE RADIATION