Astronomy and Astrophysics – Astrophysics
Scientific paper
1999-07-22
Phys.Rept. 333 (2000) 33-45
Astronomy and Astrophysics
Astrophysics
latex (using elsart macro for Physics Reports), 16 pages including 4 figures. To appear in Physics Reports, David Schramm Memo
Scientific paper
10.1016/S0370-1573(00)00014-4
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 $11.5 \pm 1.3$ Gyr, implying a one-sided 95% confidence level lower limit of 9.5 Gyr, if statistical parallax distance measures are not incorporated. Incorporating more recent measures, including Hipparcos based statistical parallax measures, raises the mean predicted age to $12.8 \pm 1$ Gyr, with a 95 % confidence range of 10-17 Gyr. I conclude by discussing possible improvements which may allow a more precise age distribution in the near future.
No associations
LandOfFree
The Age of Globular Clusters does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The Age of Globular Clusters, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Age of Globular Clusters will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-286075