منابع مشابه
Globular cluster ages.
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 simultaneo...
متن کاملGlobular Cluster Ages and Strömgren CCD Photometry
Strömgren 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 th...
متن کاملGlobular Cluster Ages and the Formation of the Galactic Halo
Main sequence turno magnitudes from the recent set of Yale isochrones (Chaboyer et al. 1995) have been combined with a variety of relations for the absolute magnitude of RR Lyr stars (Mv(RR)) to calibrate age as a function of the di erence in magnitude between the main sequence turn-o and the horizontal branch ( V HB). A best estimate for the calibration of Mv(RR) is derived from a survey of th...
متن کاملThe Relative Ages of the Globular Cluster Subpopulations in M87
Relative ages for the globular cluster (GC) subpopulations in the Virgo giant elliptical galaxy M87 (NGC 4486) have been determined from Strömgren photometry obtained with WFPC2 on board HST. Using a variety of population synthesis models, and assuming the GC mass at the turnover of the luminosity function is the same for both subpopulations, differential ages have been determined from the obse...
متن کاملA new method to determine Globular Cluster ages
We present a new method to compute stellar ages in Globular Clusters (GC) that is ten times more precise than the traditional isochrone fitting procedure. The method relies on accurate stellar evolutionary tracks and on photometry for GCs complete down to the main sequence, and it is based on counting number of stars in two different regions of the CMD: the red giant branch and the main-sequenc...
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ژورنال
عنوان ژورنال: Highlights of Astronomy
سال: 1983
ISSN: 1539-2996
DOI: 10.1017/s1539299600005219