Related papers: Age dating old globular clusters in early-type gal…
We extend our previous method to determine globular cluster ages using the luminosity function (Jimenez \& Padoan 1996). We show that the luminosity function depends on both age and distance modulus and that it is possible to distinguish…
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…
In integrated-light, some color-color diagrams that use optical and near-infrared photometry show surprisingly orthogonal grids as age and metallicity are varied, and they are coming into common usage for estimating the average age and…
Globular cluster ages are more than just lower limits to the age of the universe; the distribution of ages constraints the timescales for galaxy formation and chemical evolution. Globular cluster populations with different metallicities…
New calibrations of spectrophotometric indices of elliptical galaxies as functions of spectrophotometric indices are presented, permitting estimates of mean stellar population ages and metallicities. These calibrations are based on…
We establish a framework for determing absolute ages of Galactic globular clusters and then use these ages to investigate the age-metallicity and age-Galactocentric distance relations for the 36 clusters with the most reliable age data. The…
Visual and near-infrared colours are used to identify intermediate-age globular cluster in early-type galaxies. In NGC5846 and NGC4365 colour-colour diagrams (V-I vs. V-K) reveal a sub-population in the globular cluster systems with an age…
Determining reliable ages for old stellar objects at different redshifts offers a powerful means to constrain cosmology without relying on a specific cosmological model: this is known as the cosmic clocks method. Globular clusters (GCs),…
We have determined spectroscopic ages of elliptical galaxies in the Virgo cluster using spectra of very high signal-to-noise ratio (S/N/A > 100). We observed 8 galaxies with the Subaru Telescope and have combined this sample with 6 galaxies…
We present our new, fully-automated method to detect and measure the ages of star clusters in nearby galaxies, where individual stars can be resolved. The method relies purely on statistical analysis of observations and Monte-Carlo…
We present accurate relative ages for a sample of 55 Galactic globular clusters. The ages have been obtained by measuring the difference between the horizontal branch and the turnoff in two, internally photometrically homogeneous databases.…
Determining the properties of old stellar populations (those with age >1 Gyr) has long involved the comparison of their integrated light, either in the form of photometry or spectroscopic indexes, with empirical or synthetic templates. Here…
We present the results of our analysis of the photometric data of globular clusters in the elliptical galaxy NGC 5128 (Cen A). We show that the integrated colour U-B can be an effective metallicity indicator for simple stellar populations.…
Recent developments relevant to the formation of globular cluster systems in galaxies are discussed, including (1) The age distribution of the oldest Milky Way clusters, (2) Subgroups and possible accretion and merger remnants in the…
We present an estimate of the absolute age of 68 galactic globular clusters obtained by exploiting the distribution of stars in the full color-magnitude diagram. In particular, we jointly estimate the absolute age, distance, reddening,…
An analysis of ages, metallicities, and [alpha/Fe] ratios of globular cluster systems in early-type galaxies is presented, based on Lick index measurements summarized in Puzia et al. (2004, Paper I of this series). In the light of…
We present preliminary results from our on-going survey of Galactic globular clusters relative ages. The investigation is based on V,I images obtained at the ESO and La Palma telescopes, which make up the largest homogenous photometric…
Globular clusters are the oldest objects in the Galaxy whose age may be accurately determined. As such globular cluster ages provide the best estimate for the age of the universe. The age of a globular cluster is determined by a comparison…
Globular Cluster Systems (GCSs) of most early-type galaxies feature two peaks in their optical colour distributions. Blue-peak GCs are believed to be old and metal-poor, whereas the ages, metallicities, and the origin of the red-peak GCs…
As the oldest building blocks of our Galaxy, globular clusters retain the archaeological footprint of the early stellar environments. Accurate absolute ages of globular clusters are required to interpret this ancient record. Existing dating…