Related papers: Ages of globular clusters: a new approach
Most Globular Clusters (GC) show chemical inhomogeneities in the composition of their stars, apparently due to a second stellar generation (SG) in which the forming gas is enriched by hot-CNO cycled material processed in stars belonging to…
In this study, we extend the dust-independent Hatzidimitriou (1991) relation between cluster age and $d_{B-R}$ color difference between the red giant branch (RGB) and red clump to younger cluster ages. We perform membership analysis on…
As first Paper of a series devoted to study the old stellar population in clusters and fields in the Small Magellanic Cloud, we present deep observations of NGC121 in the F555W and F814W filters, obtained with the Advanced Camera for…
Recent discoveries have put the picture of stellar clusters being simple stellar populations into question. In particular, the color-magnitude diagrams of intermediate age (1-2 Gyr) massive clusters in the Large Magellanic Cloud (LMC) show…
We illustrate the application of high precision Stromgren uvby photometry to open and globular clusters (GCs). It is shown how such data can be used to determine cluster ages, independent of distance and only weakly dependent on reddening.…
High precision trigonometric parallaxes from the HIPPARCOS satellite and accurate metal abundances ([Fe/H], [O/Fe], and [alpha/Fe]) from high resolution spectroscopy for about 30 local subdwarfs have been used to derive distances and ages…
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…
The large majority of extragalactic star cluster studies done to date have essentially used two or three-passband aperture photometry, combined with theoretical stellar population synthesis models, to obtain age estimates. The accuracy to…
The WFPC2 camera on HST has been used to obtain deep main sequence photometry of the low-metallicity ([Fe/H]=-2.14), outer-halo globular cluster NGC 2419. A differential fit of the NGC 2419 CMD to that of the similarly metal-poor \ standard…
We present a result of age estimation for star clusters in M33. We obtain color-magnitude diagrams (CMDs) of resolved stars in 242 star clusters from the HST/WFPC2 images. We estimate ages of 100 star clusters among these, by fitting the…
We are using full spectrum fitting to determine the ages and metallicities of Galactic clusters (M67 and globular clusters). We find that the method is very accurate to measure the metallicity. Blue horizontal branches are well identified…
The globular cluster M79 was observed with the Hopkins Ultraviolet Telescope (HUT) during the Astro-1 space shuttle mission in 1990 December. The cluster's far-UV integrated spectrum shows strong absorption in the Lyman lines of atomic…
Spectra of galaxies contain an enormous amount of information about the relative mixture of ages and metallicities of constituent stars. We present a comprehensive study designed to extract the maximum information from spectra of data…
We review five independent techniques which are used to set the distance scale to globular clusters, including subdwarf main sequence fitting utilizing the recent Hipparcos parallax catalogue. These data together all indicate that globular…
We present an analysis of compact star clusters in deep HST/WFPC2 images of NGC 1275. B and R band photometry of roughly 3000 clusters shows a bimodality in the B-R colors, suggesting that distinct old and young cluster populations are…
We discuss the present state of knowledge and thought concerning the spread in age found among Galactic globular clusters, with some discussion of the implications for what happened during the earliest stages of the formation of the Milky…
We here present our first attempt to use Globular Clusters as tracers of their parent galaxy's formation history. Globular Cluster Systems of most early-type galaxies feature two peaks in their optical colour distributions. Blue-peak…
Globular clusters (GCs) provide statistically significant coeval populations of stars spanning various evolutionary stages, allowing robust constraints on stellar evolution model parameters and ages. We analyze eight old Milky Way GCs with…
Very deep images of the Galactic globular cluster M4 (NGC 6121) through the F606W and F814W filters were taken in 2001 with the WFPC2 on board the HST. A first published analysis of this data set (Richer et al. 2002) produced the result…
We report the results of the observations in the JHK bands of 12 globular clusters in the LMC, and present CMDs down to K=16 for about 450 stars. We merge the data with the BV ones presented in paper I and use the merged data to study the…