Astronomy and Astrophysics – Astrophysics
Scientific paper
1999-09-23
Astronomy and Astrophysics
Astrophysics
8 pages, 4 figures, uses paspconf.sty to appear in the PASP Conference Proceedings series of the Workshop on "Spectrophotometr
Scientific paper
Stromgren uvby CCD photometry can be used in a variety of ways to constrain the absolute and relative ages of globular clusters. The reddening corrected (v-y, c1) diagram offers the means to derive ages that are completely independent of distance. Very precise differential ages for clusters of the same chemical composition may also be determined from such 2-color plots, or from measurements of the magnitude difference, Delta_u, between the subgiant and horizontal branches on the $u-y, u$ plane (where both of these features are flat and well-defined, even for clusters like M13 that have extremely blue HBs on the (B-V, V) diagram). Based on high-quality photometry we find that: (1) M92 is 15 Gyr old, (2) M3 and M13 differ in age by < 1 Gyr, and (3) NGC 288, NGC 362, and NGC 1851 are coeval to within ~1.5 Gyr. These results strongly suggest that age cannot be the only ``second parameter''. Finally, we suggest that the observed variations in c1 among giant branch stars in all the metal-poor clusters that we have studied so far are likely due to star-to-star C and N abundance variations, and potentially indicate that most (if not all) globular clusters have ``primordial'' variations in at least these elements.
No associations
LandOfFree
Globular Cluster Ages and Stromgren CCD Photometry 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 Globular Cluster Ages and Stromgren CCD Photometry, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Globular Cluster Ages and Stromgren CCD Photometry will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-682502