Globular cluster ages | Zendy

Raúl Jiménez | Zendy

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Globular cluster ages

Author(s) -

Raúl Jiménez

Publication year - 1998

Publication title -

proceedings of the national academy of sciences

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 5.011

H-Index - 771

eISSN - 1091-6490

pISSN - 0027-8424

DOI - 10.1073/pnas.95.1.13

Subject(s) - globular cluster , distance modulus , physics , astrophysics , hubble's law , luminosity , horizontal branch , luminosity function , apparent magnitude , confidence interval , absolute magnitude , omega , cluster (spacecraft) , cosmology , stars , statistics , galaxy , dark energy , mathematics , computer science , programming language , quantum mechanics

We review two new methods to determine the age of globular clusters (GCs). These two methods are more accurate than the classical isochrone fitting technique. The first method is based on the morphology of the horizontal branch and is independent of the distance modulus of the globular cluster. The second method uses a careful binning of the stellar luminosity function and determines simultaneously the distance and age of the GC. We find that the oldest galactic GCs have an age of 13.5 +/- 2 gigayears (Gyr). The absolute minimum age for the oldest GCs is 10.5 Gyr (with 99% confidence) and the maximum 16.0 Gyr (with 99% confidence). Therefore, an Einstein-De Sitter Universe (Omega = 1) is not totally ruled out if the Hubble constant is about 65 +/- 10 Km s-1 Mpc-1.

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