The main-sequence turnoff of the old SMC globular cluster NGC 121
1985; IOP Publishing; Volume: 298; Linguagem: Inglês
10.1086/163639
ISSN1538-4357
AutoresL. L. Stryker, G. S. Da Costa, J. R. Mould,
Tópico(s)Astronomical Observations and Instrumentation
Resumoview Abstract Citations (73) References (44) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The main-sequence turnoff of the old SMC globular cluster NGC121 Stryker, L. L. ; Da Costa, G. S. ; Mould, J. R. Abstract The age of the SMC globular cluster NGC 121 is found from main-sequence isochrone fitting to be 12 + or - 2 x 10 to the 9th yr if a distance modulus that assumes M(v) = +0.6 for the field RR Lyrae variables near the cluster is used. If instead (m - M)0 = 19.3, then the cluster age is 9 + or - 2 x 10 to the 9th yr. The cluster is known to contain both RR Lyrae variables and a marginal carbon star; comparison with theoretical models indicates no significant inconsistencies in this joint occurrence at either modulus. The color-magnitude diagram for the mearby field also shows a faint, blue main-seqence turnoff and, in contrast to previous Magellanic Cloud field studies, the field lacks any evidence for the existence of a significant intermediate-age component. A new look at the chemical evolution of the Small Magellanic Cloud suggests that, unlike the galaxy, where the rate of enrichment has been steady after the initial phase, the enrichment in the SMC remaned small for a long interval before increasing rapidly sometime in the last 1-2 x 10 to the 9th yr. Publication: The Astrophysical Journal Pub Date: November 1985 DOI: 10.1086/163639 Bibcode: 1985ApJ...298..544S Keywords: Astronomical Photometry; Chronology; Color-Magnitude Diagram; Globular Clusters; Magellanic Clouds; Carbon Stars; Cepheid Variables; Stellar Evolution; Tables (Data); Astrophysics full text sources ADS | data products SIMBAD (6) NED (1) CDS (1)
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