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The late-type stellar content of Magellanic Cloud clusters

Frogel, Jay A. and Cohen, Judith G. (1982) The late-type stellar content of Magellanic Cloud clusters. Astrophysical Journal, 253 . pp. 580-592. ISSN 0004-637X. doi:10.1086/159660.

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New broad-band infrared photometric data have been obtained for 48 late-type giants in clusters in the Magellanic Clouds (MC). Visual spectrophotometry was obtained for a subset of these stars. These observations are combined with published data for MC cluster stars and then compared with similar data for MC field giants and with predictions of various evolutionary schemes for cool, luminous, carbon and oxygen rich stars. The MC cluster C stars are found to have a range in spectral energy distributions which is quite similar to that of MC field C stars. The luminosity function of the cluster C stars has a mean M_(bol) = —4.76 with a dispersion of ±0.36, also quite similar to the values for MC field C stars. However, the dispersion of the cluster C stars in M_K_0 at a given (J— K)_0 is between 2 and 3 times less than it is for the field C stars. This can arise if the present sample of clusters has a significantly smaller spread in age and/or metallicity than the progenitors of the field C stars. The LMC field contains M giants which are redder and more luminous than any so far found in LMC or SMC clusters. This is attributed to the presence in the LMC field of a significant population of stars which are younger and/or more metal rich than the stars in the cluster sample. Differences which are found to exist between the M star populations of the LMC and the SMC clusters are also attributed to age and/or metallicity effects. In all but one of the MC clusters which have both M and C stars, the faintest C star is brighter than the brightest M star. Such a “transition” luminosity appears to be correlated with the location of the cluster in the one-dimensional classification sequence of Searle, Wilkinson, and Bagnuolo, and it can be a useful criterion in the evaluation of theories of carbon star evolution. Finally, although the spectrophotometric data suggest that the LMC “halo-type” globular, NGC 1841 and 2257, have metallicities similar to one another and to that of M3, the locations of the NGC 1841 stars in a C-M diagram appear to be anomalous in the sense that its brightest stars have luminosities greater than the tips of giant branches of metal poor galactic globular clusters.

Item Type:Article
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Cohen, Judith G.0000-0002-8039-4673
Additional Information:© American Astronomical Society • Provided by the NASA Astrophysics Data System. Received 1981 March 24; accepted 1981 July 6. Cerro Tololo Inter-American Observatory is operated by AURA, Inc. under National Science Foundation contract No. AST 78-27879. We thank Jay Elias and John Hackwell for a number of useful comments on an earlier version of this manuscript and Marc Aaronson and Jeremy Mould for indicating to us some of the red giant candidates in NGC 1841 and 2257. J. G. C. is grateful for a grant from the Caltech Recycling Center.
Funding AgencyGrant Number
NSFAST 78-27879
Caltech Recycling CenterUNSPECIFIED
Subject Keywords:clusters: globular — galaxies: Magellanic Clouds — galaxies: stellar content — stars: late-type
Record Number:CaltechAUTHORS:20190531-091631963
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:95981
Deposited By: George Porter
Deposited On:03 Jun 2019 14:37
Last Modified:16 Nov 2021 17:17

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