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The deep luminosity function of the globular cluster M30

Piotto, Giampaolo and King, Ivan R. and Capaccioli, Massimo and Ortolani, Sergio and Djorgovski, S. (1990) The deep luminosity function of the globular cluster M30. Astrophysical Journal, 350 . pp. 662-671. ISSN 0004-637X. https://resolver.caltech.edu/CaltechAUTHORS:20190816-142949859

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Abstract

This paper is aimed at determining the mass function in the low-metallicity, post-core collapse globular cluster NGC 7099 = M30, and analyzing its radial trend. New deep CCD photometry is presented in two fields centered at r = 2'.9 and 4'.4 from the center, respectively. We confirm that a good representation of the color-magnitude diagrams is obtained by oxygen-enhanced isochrones (as used by Capaccioli, Ortolani, and Piotto). The best fit yields (m - M)_v = 14.65, E(B-V) = 0.05, and an age of 16 Gyr. Luminosity functions down to V≃25 (M_v≃10.3) are constructed and carefully corrected for contamination by field objects and for incompleteness (see Appendix). Comparison with standard theoretical luminosity functions shows that the mass function, modeled with a power law, has an index x≃1, at variance with the x≃0 found by Richer, Fahlman, and VandenBerg for a field centered at r = 3'.4. An even steeper slope is given by the photometry in an outer field of M30 studied with the 4 m CTIO CCD camera (Piotto et al.). All together, our data agree with the trend of x found by Pryor, Smith, and McClure for a multimass King-Michie model (with or without velocity anisotropy), yielding a global slope x_0 ~0.7. Mass segregation is implied, though marginally, given the errors and the small variation of x expected on theoretical grounds in the radial range explored by our observations. M30 is found to deviate strongly from the mass-function slope versus metallicity relation (McClure et al.); its mass function is as fiat as that of intermediate-metallicity clusters.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1086/168418DOIArticle
ORCID:
AuthorORCID
Djorgovski, S.0000-0002-0603-3087
Additional Information:© 1990 American Astronomical Society. Provided by the NASA Astrophysics Data System. Received 1989 March 24; accepted 1989 August 10. Based on observations collected at the European Southern Observatory, La Silla, and at Cerro Tololo Inter-American Observatory. G. P. is a Visiting Astronomer at the European Southern Observatory, La Silla, Chile. S. D. is a Visiting Astronomer at Cerro Tololo Inter-American Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under contract with the National Science Foundation. We wish to thank R. Walterbos for his help in the computation of the foreground contamination with his revised version of the Bahcall and Soneira code and N. Metcalfe for communicating the Durham galaxy counts to us in advance of publication. G. P. acknowledges the hospitality of the Department of Astronomy, University of California at Berkeley, and the Fondazione Ing. A. Gini for partial support. The work done at Berkeley was supported by NASA Contract NAS5-28086. S. D. was supported in part by funds from Harvard University and California Institute of Technology.
Funders:
Funding AgencyGrant Number
Fondazione Ing. Aldo GiniUNSPECIFIED
NASANAS5-28086
Harvard UniversityUNSPECIFIED
CaltechUNSPECIFIED
Subject Keywords:clusters: globular - luminosity function - stars: abundances - stars: evolution
Record Number:CaltechAUTHORS:20190816-142949859
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20190816-142949859
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:97960
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:16 Aug 2019 21:55
Last Modified:03 Oct 2019 21:36

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