Related papers: Is the galactic disk older than the halo?
This is the third article in a series aimed at computing accurate and precise ages of galactic globular clusters from their full color-magnitude diagram in order to estimate the age of the Universe and in turn constrain the cosmological…
The ages and metallicities of globular clusters play an important role not just in testing models for their formation and evolution but in understanding the assembly history for their host galaxies. Here we use a combination of imaging and…
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…
CONTEXT. The maximum size of the Galactic stellar disk is not yet known. Some studies have suggested an abrupt drop-off of the stellar density of the disk at Galactocentric distances $R\gtrsim 15$ kpc, which means that in practice no disk…
A recent study shows, from an empirical deduction, that the number and the presence of the blue straggler stars (BSS) in an open cluster follow a function whose components are the ratio between age and the relaxation time, $\it f$, and a…
We present new integrated light spectroscopy of globular clusters (GCs) in NGC 5128 in order to measure radial velocities and derive ages, metallicities, and alpha-element abundance ratios. Using Gemini-S 8-m/GMOS, we obtained spectroscopy…
Globular cluster ages provide both an important test of models of globular cluster formation and a powerful method to constrain the assembly history of galaxies. Unfortunately, measuring the ages of unresolved old stellar populations has…
We present spectroscopic ages, metallicities, and [alpha/Fe] ratios for 70 globular clusters in M31 that were derived from Lick line-index measurements. In addition to a population of old (>10 Gyr) globular clusters with a wide range of…
The distribution of size as a function of age observed for star clusters in the Large Magellanic Cloud (LMC) is very puzzling: young clusters are all compact, while the oldest systems show both small and large sizes. It is commonly…
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 results of a study of the galactic open cluster population based on the all-sky catalogue ASCC-2.5 (I/280A) compiled from Tycho-2, Hipparcos and other catalogues. The sample of optical clusters from ASCC-2.5 is complete up to…
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 age and chemical characteristics of the Galactic bulge link to the formation and evolutionary history of the Galaxy. Data-driven methods and large surveys enable stellar ages and precision chemical abundances to be determined for vast…
Spatial, kinematic, and orbital properties, along with ages and chemical compositions of the thin disc, thick disc, and various stellar substructures in the halo, are studied based on data from the LAMOST and Gaia surveys. The star…
We compare optical and near-infrared colors of disks and bulges in a diameter-limited sample of inclined, bright, nearby, early-type spirals. Color profiles along wedge apertures at 15 degree from the major axis and on the minor axis on the…
Until recently it was thought that high Galactic latitude clouds were a non-star-forming ensemble. However, in a previous study we reported the discovery of two embedded clusters (ECs) far away from the Galactic plane ($\sim5$ kpc). In our…
Multiple generations of stars are routinely encountered in globular clusters but no convincing evidence has been found in Galactic open clusters to date. In this paper we use new photometric and spectroscopic data to search for multiple…
The global properties of all known Galactic globular clusters are examined. The relationship between the luminosities and the metallicities of Galactic globular clusters is found to be complex. Among luminous clusters there is a correlation…
Recent results by Bensby and collaborators on the ages of microlensed stars in the Galactic bulge have challenged the picture of an exclusively old stellar population. However, these age estimates have not been independently confirmed. In…
After taking into account, for the first time, the detailed systematic variation of horizontal-branch (HB) morphology with age and metallicity, our population synthesis models show that the integrated H beta index is significantly affected…