An accurate relative age estimator for globular clusters

Brian Chaboyer, H. Pierre Demarque, Peter J. Kernan, Lawrence Krauss, Ata Sarajedini

Research output: Contribution to journalArticle

54 Citations (Scopus)

Abstract

Globular cluster age estimates based on the absolute magnitude of the main-sequence turn-off [Mv(TO)] are generally considered to be the most reliable from a theoretical viewpoint. However, the difficulty in determining Mv(TO) in observed colour-magnitude diagrams leads to a large error in the derived age. In this paper, we advocate the use of the absolute magnitude of the point which is brighter than the turn-off and 0.05 mag redder [Mv(BTO)] as a precision age indicator. It is easy to measure this point on observed colour-magnitude diagrams, leading to small observational error bars. Furthermore, an extensive Monte Carlo calculation indicates that the theoretical uncertainty in Mv(BTO) is similar to Mv(TO). As a result, ages derived using Mv(BTO) are at least a factor of 2 more precise than those derived using Mv(TO). This technique is applied to the globular cluster M68 and an age of 12.8 ± 0.3 Gyr is derived [assuming Mv(RR) = 0.20[Fe/H] + 0.98], indicating that M68 is a 'young' globular cluster. A homogeneous set of globular cluster age estimates with this precision would provide unprecedented insight into the formation of the Galactic halo.

Original languageEnglish (US)
Pages (from-to)683-689
Number of pages7
JournalMonthly Notices of the Royal Astronomical Society
Volume283
Issue number2
StatePublished - 1996
Externally publishedYes

Fingerprint

globular clusters
estimators
color-magnitude diagram
galactic halos
estimates
diagram

Keywords

  • Globular clusters: general
  • Globular clusters: individual: M68
  • Methods: data analysis
  • Stars: evolution
  • Stars: interiors
  • Stars: population II

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Chaboyer, B., Demarque, H. P., Kernan, P. J., Krauss, L., & Sarajedini, A. (1996). An accurate relative age estimator for globular clusters. Monthly Notices of the Royal Astronomical Society, 283(2), 683-689.

An accurate relative age estimator for globular clusters. / Chaboyer, Brian; Demarque, H. Pierre; Kernan, Peter J.; Krauss, Lawrence; Sarajedini, Ata.

In: Monthly Notices of the Royal Astronomical Society, Vol. 283, No. 2, 1996, p. 683-689.

Research output: Contribution to journalArticle

Chaboyer, B, Demarque, HP, Kernan, PJ, Krauss, L & Sarajedini, A 1996, 'An accurate relative age estimator for globular clusters', Monthly Notices of the Royal Astronomical Society, vol. 283, no. 2, pp. 683-689.
Chaboyer B, Demarque HP, Kernan PJ, Krauss L, Sarajedini A. An accurate relative age estimator for globular clusters. Monthly Notices of the Royal Astronomical Society. 1996;283(2):683-689.
Chaboyer, Brian ; Demarque, H. Pierre ; Kernan, Peter J. ; Krauss, Lawrence ; Sarajedini, Ata. / An accurate relative age estimator for globular clusters. In: Monthly Notices of the Royal Astronomical Society. 1996 ; Vol. 283, No. 2. pp. 683-689.
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