The Evolution of the Galactic Globular Clusters. II. Helium Abundances and Ages.

Details The Evolution of the Galactic Globular Clusters. II. Helium Abundances and Ages. The Evolution of the Galactic Globular Clusters. II. Helium Abundances and Ages.

Dec 1985

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1985jkas...18...41l&link_type=abstract

Journal of the Korean Astronomical Society, vol. 18, no. 1, P.41-69

Astronomy and Astrophysics

Astronomy

1

Scientific paper

For the well observed 16 globular clusters with known metal abundances(Z), the helium abundances(Y) and ages are determined by various methods, and the relations between Y,Z and age are examined. The luminosity Lrr of RR Lyrae stars is known to be dependent of evolutionary models and pulsation theory in the sense that the pulsation theory and horizontal branch(HB) models yield the anticorrelation between Lrr and Z whereas main sequence(MS) and red giant branch(RGB) models yield the direct correlation between them. Similarly the anticorrelation between Y and Z is obtained from the HB models and pulsation theory whereas the direct correlation between them is obtained when the RGB model is applied. The current evolutionary models yield the anticorrelation between Z and age of clusters whenever the direct correlation between Y and Z holds. However when the anticorrelation between Y and Z is applied for age determination, the similar age of clusters is obtained as shown by Sandage(1982b). The ages, which are determined by the fitting of C-M diagrams to isochrones in the (Mv, B-V)-plane, suggest the two different chemical enrichment processes, which could be accounted for by the disk-halo model for the chemical evolution of the Galaxy(Lee and Ann 1981). Also it is known that the R-method is very useful for Y-determination and the derived Y's show the increasing rate of deltaY over deltaZ =0.5 which is comparable to the observed value of deltaY over deltaZ = 0.3 from HII regions and planetary nebulae by Peimbert and Torres-Peimbert(1976). In this case, the age-metallicity relation of globular clusters could be explained by the disk-halo model.

Affiliated with

Also associated with

No associations

Rating

The Evolution of the Galactic Globular Clusters. II. Helium Abundances and Ages. 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 Evolution of the Galactic Globular Clusters. II. Helium Abundances and Ages., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Evolution of the Galactic Globular Clusters. II. Helium Abundances and Ages. will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1162548