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Bolometric luminosities and infrared properties of carbon stars in the Magellanic Clouds and the Galaxy

Cohen, Judith G. and Frogel, Jay A. and Persson, S. E. and Elias, Jonathan H. (1981) Bolometric luminosities and infrared properties of carbon stars in the Magellanic Clouds and the Galaxy. Astrophysical Journal, 249 . pp. 481-503. ISSN 0004-637X. https://resolver.caltech.edu/CaltechAUTHORS:20190531-091631781

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Abstract

Broad band J, H, K photometry and narrow band CO and H_2O indices have been obtained for 89 luminous red stars in the Large Magellanic Cloud (LMC) and 21 in the Small Magellanic Cloud (SMC), chosen largely from the sample of Blanco, McCarthy, and Blanco. Most are known to be carbon stars, and their infrared properties are compared with new observations of 33 galactic carbon stars. The bolometric luminosity distributions of an unbiased sample of Magellanic Cloud carbon stars are compared with those predicted from evolutionary calculations by Renzini and Voli for double shell burning stars undergoing He shell flashes. The observed and theoretical distributions disagree markedly: nearly all the observed stars have lower luminosities than even the faintest theoretical carbon star. In addition, we find many fewer than expected high luminosity stars with initial mass greater than 3 M_⊙. Possible explanations for this include a steep initial mass function for intermediate mass stars, a star formation rate significantly higher in the past than at present, or a neglected physical effect, such as underestimation of the importance of mass loss. Nevertheless, it appears that the hypothesis that He shell flashes lead to a dredge-up of carbon into the envelope, which results in a carbon star, can be maintained, if dredging occurs after fewer shell flashes than are predicted by presently available stellar evolutionary calculations. The colors and indices of the late M giants in the LMC field are similar to those of late M giants in the Galaxy. The narrow band infrared data are interpreted qualitatively in terms of the effects of molecular band absorption, which also strongly influences the infrared broad band colors of carbon stars. The small differences in the color-color relationships of the SMC and LMC samples are consistent with the differences in heavy metal abundance between the LMC, SMC, and Galaxy.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1086/159308DOIArticle
http://adsabs.harvard.edu/abs/1981ApJ...249..481CADSArticle
ORCID:
AuthorORCID
Cohen, Judith G.0000-0002-8039-4673
Additional Information:© American Astronomical Society • Provided by the NASA Astrophysics Data System. Received 1980 December 1; accepted 1981 April 27. Cerro Tololo Inter-American Observatory is supported by the National Science Foundation under Contract No. AST 78-27879. We are extremely grateful to Victor Blanco, Martin McCarthy, and Betty Blanco for permitting us to use the results of their survey before publication. We also wish to acknowledge the stimulus provided by Icko Iben and Alvio Renzini. This research was supported in part by NSF grant AST 76-22676 and by a grant from the Caltech Recycling Center.
Funders:
Funding AgencyGrant Number
NSFAST 78-27879
NSFAST 76-22676
Caltech Recycling CenterUNSPECIFIED
Subject Keywords:galaxies: Magellanic Clouds— galaxies: stellar content — luminosity function — stars: abundances— stars: carbon— stars: luminosities
Record Number:CaltechAUTHORS:20190531-091631781
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20190531-091631781
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:95979
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:03 Jun 2019 21:08
Last Modified:03 Oct 2019 21:18

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