The age of globular clusters

Lawrence M. Krauss

Research output: Contribution to journalShort survey

16 Scopus citations

Abstract

I review here recent developments which have affected our understanding of both the absolute age of globular clusters and the uncertainties in this age estimate, and comment on the implications for cosmological models. This present estimate is in agreement with the range long advocated by David Schramm. The major uncertainty in determining ages of globular clusers based upon the absolute magnitude of the main sequence turn-off remains the uncertainty in the distance to these clusters. Estimates of these distances have recently been upwardly revised due to Hipparcos parallax measurements, if one calibrates luminosities of main sequence stars. However, it is important to realize that at the present time, different distance measures are in disagreement. A recent estimate is that the oldest clusters are 11.5±1.3 Gyr, implying a one-sided 95% confidence level lower limit of 9.5Gyr, if statistical parallax distance measures are not incorporated. Incorporating more recent measures, including Hipparcos-based statistical parallax measures, raises the mean predicted age to 12.8±1Gyr, with a 95% confidence range of 10-17Gyr. I conclude by discussing possible improvements which may allow a more precise age distribution in the near future.

Original languageEnglish (US)
Pages (from-to)33-45
Number of pages13
JournalPhysics Report
Volume333-334
Issue number4-6
DOIs
StatePublished - Aug 2000

Keywords

  • 96.30.Ks
  • 96.40.Jw
  • 98.80. - v
  • Cosmology
  • Globular clusters
  • Stellar evolution

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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