Related papers: Age and Metallicity Effects in Omega Centauri
Hubble Space Telescope observations of globular clusters (GCs) in the Antennae galaxy show clusters of clusters, or regions in the galaxy that span hundreds of parsecs, where many of the GCs are doomed to collide, and eventually merge.…
The origin of a double main-sequence (MS) in omega Centauri is explored. We have shown from theoretical calculations on the stellar evolution that the colors of MS stars are shifted to those of the observed blue MS if the surface layers are…
The X-ray emission by hot gas around the central galaxies of galaxy clusters is commonly modeled assuming the existence of steady-state, multiphase cooling flows. The inflowing gas will be chemically enriched by type Ia supernovae and…
We present high-quality, Keck spectroscopic data for a sample of 20 globular clusters (GCs) in the massive E0 galaxy NGC1407. A subset of twenty line-strength indices of the Lick/IDS system have been measured for both the GC system and the…
The photometric colors of globular clusters (GCs) act as effective proxies for metallicity, since all normally used optical/IR color indices exhibit a nonlinear but monotonic relation between their integrated color and their metallicity.…
We use our new, flux-calibrated stellar population model of absorption-line indices to derive ages, metallicities, and various element abundance ratios from integrated light spectroscopy of galactic globular clusters. The ages agree well…
Several recent studies of Solar twins in the Solar neighbourhood have shown a tight correlation between various elemental abundances and age, in particular [Y/Mg]. If this relation is real and valid for other types of stars as well as…
The dominant stellar population of the central bulge of the Milky Way is old, with roughly solar metallicity. The age is very similar to that of the old metal rich bulge globular clusters and to 47 Tucanae, which has an age of 13 Gyr.…
Omega Centauri ($\omega$ Cen) is the Milky Way's most massive globular cluster and is likely the stripped nucleus of an accreted dwarf galaxy. In this paper, we analyze $\omega$ Cen's kinematics using data from oMEGACat, a comprehensive…
The effects of metallicity on the evolution of protoplanetary disks may be studied in the outer Galaxy where the metallicity is lower than in the solar neighbourhood. We present the VLT/KMOS integral field spectroscopy in the near-infrared…
We present a quantitative spectral analysis of five very massive stars in the Arches cluster, located near the Galactic center, to determine stellar parameters, stellar wind properties and, most importantly, metallicity content. The…
The mean color of globular clusters (GCs) in early-type galaxies is in general bluer than the integrated color of halo field stars in host galaxies. Metal-rich GCs often appear more associated with field stars than metal-poor GCs, yet show…
The observed characteristics of globular cluster (GC) systems, such as metallicity distributions, are commonly used to place constraints on galaxy formation models. However, obtaining reliable metallicity values is particularly difficult…
By means of N-body/hydrodynamical simulations we model the evolution of a primordial 10^{8} solar masses density peak which ends up in an object closely resembling the present day globular cluster Omega Centauri. We succeed to reproduce the…
[Abbreviated] We have investigated the color-magnitude diagram of Omega Centauri and find that the blue main sequence (bMS) can be reproduced only by models that have a of helium abundance in the range Y=0.35-$0.40. To explain the faint…
Ca II triplet spectroscopy has been used to derive stellar metallicities for individual stars in four LMC fields situated at galactocentric distances of 3\arcdeg, 5\arcdeg, 6\arcdeg\@ and 8\arcdeg\@ to the north of the Bar. Observed…
Omega Centauri ($\omega$ Cen) is one of the most complex star clusters in the Milky Way, and likely the stripped nucleus of an accreted dwarf galaxy. Being the subject of debate between it hosting an intermediate-mass black hole (IMBH) or a…
We first present a self-consistent dynamical model in which $\omega$ Cen is formed from an ancient nucleated dwarf galaxy merging with the first generation of the Galactic thin disc in a retrograde manner with respect to the Galactic…
Constraining the helium enhancement in stars is critical for understanding the formation mechanisms of multiple populations in star clusters. However, measuring helium variations for many stars within a cluster remains observationally…
The nature and formation history of our Galaxy's largest and most enigmatic stellar cluster, known as Omega Centauri (ocen) remains debated. Here, we offer a novel approach to disentangling the complex stellar populations within ocen based…