Related papers: Is the galactic disk older than the halo?

The halo and disc globular cluster population can be used as a tracer of the primordial epochs of the Milky Way formation. In this work, literature data of globular clusters ages, chemical abundances, and structural parameters are studied,…

We investigate the evolutionary stages of four open clusters, Berkeley 39, Collinder 261, NGC 6819, and NGC 7789, of ages ranging from 1.6 -- 6 Gyr. These clusters have previously been classified into dynamically young and intermediate age…

In some scenarios for the formation of the Milky Way bulge the stellar population at the edges of the boxy bulge may be younger than those on the minor axis, or close to the Galactic center. So far the only bulge region where deep…

Deep V and I CCD images of the loosely populated Galactic globular cluster Pal 1 and the surrounding field have been obtained with the INT. A color magnitude diagram down to V(lim) ~ 24, and a luminosity function complete down to V(lim) ~…

(Abridged) We investigate the hypothesis that some fraction of the globular clusters presently observed in the Galactic halo formed in external dwarf galaxies, by means of a detailed comparison between Zinn's "old halo", "young halo", and…

Context: Analysis of ages and metallicities of star clusters in the Magellanic Clouds provide information for studies on the chemical evolution of the Clouds and other dwarf irregular galaxies. Aims: The aim is to derive ages and…

We have measured Lick index equivalent widths to derive luminosity weighted stellar ages and metallicities for thin and thick disk dominated regions of 9 edge-on disk galaxies with the ARC 3.5 meter telescope at Apache Point Observatory. In…

We use 156 044 white dwarf candidates with $\geq5\sigma$ significant parallax measurements from the Gaia mission to measure the velocity dispersion of the Galactic disc; $(\sigma_U,\sigma_V,\sigma_W) = (30.8, 23.9, 20.0)$ km s$^{-1}$. We…

We investigated the absolute age of the Galactic globular cluster M71 (NGC 6838) by using optical ground-based images (u',g',r',i',z') collected with the MegaCam camera at the Canada-France-Hawaii-Telescope (CFHT). We performed a robust…

We perform analysis of the three-dimensional kinematics of Milky Way disk stars in mono-age populations. We focus on stars between Galactocentric distances of $R=6$ and 14 \,kpc, selected from the combined LAMOST DR4 red clump giant stars…

The vast majority of Milky Way stellar halo stars were likely accreted from a small number ($\lesssim$3) of relatively large dwarf galaxy accretion events. However, the timing of these events is poorly constrained, relying predominantly on…

The vertical metallicity gradient of the Galactic disk offers valuable insights into the disk's formation and chemical evolution over time. We utilized the LAMOST-LRS young stellar sample to investigate this gradient and found that it…

Investigations of the origin and evolution of the Milky Way disk have long relied on chemical and kinematic identification of its components to reconstruct our Galactic past. Difficulties in determining precise stellar ages have restricted…

There are three independent techniques for determining the age of the universe: via cosmochronology of long-lived radioactive nuclei, via stellar modelling and population synthesis of the oldest stellar populations, and via the precision…

Old Globular Clusters (GCs) in the Milky Way have ages of about 13 Gyr, placing their formation time in the reionization epoch. We propose a novel scenario for the formation of these systems based on the merger of two or more atomic cooling…

[Abridged] We map the stellar age distribution ($\lesssim 1$ Gyr) across a 6kpc$\,\times\,$6kpc area of the Galactic disc to constrain our Galaxy's recent star-formation history. Our modelling draws on the sample of Zari et al. (2021) that…

Globular Clusters (GCs) in the Milky Way are the primary laboratories for establishing the ages of the oldest stellar populations and for measuring the color-magnitude relation of stars. In infrared (IR) color-magnitude diagrams (CMDs), the…

The age distribution of the open cluster system is a key piece of information to decipher the star formation history of the Milky Way disk. Recently, a remarkable earlier drop of its older end was found, which caught our attention.…

We present precision radial velocities and stellar population parameters for 77 star clusters in the Local Group galaxy M33. Our GTC and WHT observations sample both young, massive clusters and known/candidate globular clusters, spanning…

Oxygen and carbon are important elements in stellar populations. Their behavior refers to the formation history of the stellar populations. C and O abundances would also obviously influence stellar opacities and the overall metal abundance…