Related papers: The [Y/Mg] clock works for evolved solar metallici…
The physical processes driving chemical evolution in the Milky Way can be probed using the distribution of abundances in low-mass FGK type stars in space phase at different times. During their final stages of evolution stars experience…
Determining stellar ages is challenging, particularly for cooler main-sequence stars. Magnetic evolution offers an observational alternative for age estimation via the age-chromospheric activity (AC) relation. We evaluate the impact of…
We present the results of determination of the age, helium mass fraction (Y) in terms of the used stellar evolutionary models, metallicity ([Fe/H]), and abundances of the elements C, O, Na, Mg, Ca, Ti, Cr and Mn for 26 globular clusters of…
Models of stellar structure and evolution can be constrained by measuring accurate parameters of detached eclipsing binaries in open clusters. Multiple binary stars provide the means to determine helium abundances in these old stellar…
Excess chromospheric emissions within deep photospheric lines are effective proxies of stellar magnetism for FGK stars. This emission decays with stellar age and is a potential determinant of this important stellar quantity. We report…
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 discovery of true solar analogues is fundamental for a better understanding of the Sun and of the solar system. The open cluster M67 offers a unique opportunity to search for solar analogues because its chemical composition and age are…
The Magellanic Clouds are the most massive and closest satellite galaxies of the Milky Way, with stars covering ages from a few Myr up to 13 Gyr. This makes them important for validating integrated light methods to study stellar populations…
We present new high signal-to-noise spectroscopic data on the M31 globular cluster system, obtained with the Hectospec multifiber spectrograph on the 6.5m MMT. More than 300 clusters have been observed at a resolution of 5A. The primary…
[ABRIDGED] Metal-rich globular clusters provide important tracers of the formation of our Galaxy. Moreover, and not less important, they are very important calibrators for the derivation of properties of extra-galactic metal-rich stellar…
We built modelled spectra of stellar population at high resolution and with variable alpha-elements enhancements. Analysing spectra of Galactic globular clusters we show that it is possible to derive reliably and efficiently [Mg/Fe] using…
Canonical grids of stellar evolutionary sequences have been computed for the helium mass-fraction abundances $Y = 0.25$, $0.29$, and $0.33$, and for iron abundances that vary from $-2.4$ to $+0.4$ (in 0.2 dex increments) when [$\alpha$/Fe]…
Panoramic spectroscopic data of the sample of 80 nearby lenticular galaxies obtained with the Multi-Pupil Fiber Spectrograph of the 6-m telescope are presented. The SSP-equivalent ages, [Z/H], and [Mg/Fe] are determined through the Lick…
Methods. We used the HIRES spectrograph on the Keck I telescope to acquire high-resolution (R $\approx$ 70000) spectra with a high signal-to-noise ratio (S/N $\approx$ 400 - 650 per pixel) of HIP 100963 and the Sun for a differential…
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…
Using the theoretical stellar population synthesis models of BC96, Kong et al. (2003) showed that some BATC colors and color indices could be used to disentangle the age and metallicity effect. They found that there is a very good relation…
We present adaptive-optics assisted near-infrared high-spectral resolution observations of late-type giants in the nuclear star cluster of the Milky Way. The metallicity and elemental abundance measurements of these stars offer us an…
Within the context of a large project aimed at studying early F-, A- and late B-type stars we present the abundance analysis of the photospheres of 21 members of the open cluster NGC 5460, an intermediate age cluster (logt ~ 8.2) previously…
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…
New age determinations of the galactic disk globular clusters 47 Tuc, M71 and NGC6352 have been performed with our up-to-date alpha-enhanced stellar models. We find that all three clusters are about 9.2 Gyr old and therefore coeval with the…