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We describe a novel method for determining the demographics of a population of star clusters, for example distributions of cluster mass and age, from unresolved photometry. This method has a number of desirable properties: it fully exploits…

Astrophysics of Galaxies · Physics 2018-11-07 Mark R. Krumholz , Angela Adamo , Michele Fumagalli , Daniela Calzetti

We firstly derive the stellar population properties: age and metallicity for $\sim$ 43,000 low redshift galaxies in the seventh data release (DR7) of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) survey, which have…

Astrophysics of Galaxies · Physics 2022-01-05 Li-Li Wang , Shi-Yin Shen , A-Li Luo , Guang-Jun Yang , Ning Gai , Yan-Ke Tang , Meng-Xin Wang , Li Qin , Jin-Shu Han , Li-Xia Rong

Very metal-poor halo stars are the best candidates for being among the oldest objects in our Galaxy. Samples of halo stars with age determination and detailed chemical composition measurements provide key information for constraining the…

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…

Astrophysics · Physics 2007-08-14 M. Koleva , R. Gupta , Ph. Prugniel , H. Singh

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 have constructed a family of simple models for spiral galaxy evolution to allow us to investigate observational trends in star formation history with galaxy parameters. The models are used to generate broad band colours from which ages…

Astrophysics · Physics 2009-10-31 Eric F. Bell , Richard G. Bower

We present a sample of local red giant stars observed using the New Mexico State University 1 m telescope with the APOGEE spectrograph, for which we estimate stellar ages and the age distribution from the high-resolution spectroscopic…

Astrophysics of Galaxies · Physics 2016-01-27 Diane K Feuillet , Jo Bovy , Jon Holtzman , Leo Girardi , Nick MacDonald , Steven R Majewski , David L Nidever

The stellar population synthesis in unresolved composite objects is a very tricky problem. Indeed, it is a degenerate problem since many parameters affect the observables. The stellar population synthesis issue thus deserves a deep and…

Astrophysics · Physics 2009-11-10 J. Moultaka

In the era of large spectroscopic surveys, massive databases of high-quality spectra provide tools to outline a new picture of our Galaxy. In this framework, an important piece of information is provided by our ability to infer stellar…

Stellar ages are critical for understanding the temporal evolution of a galaxy. We calculate the ages of over 6000 red giant branch stars in the Large Magellanic Cloud (LMC) observed with SDSS-IV / APOGEE-S. Ages are derived using…

Given the wealth of data provided by Gaia and the upcoming PLATO mission, it is essential to improve stellar models to obtain accurate stellar ages. Our objective is to apply a mapping technique to estimate the age of a system and the…

Solar and Stellar Astrophysics · Physics 2026-02-10 F. Thévenin , V. A. Baturin , A. V. Oreshina , P. Morel , S. V. Ayukov , L. Bigot , A. B. Gorshkov

(Abridged) We explore the dependence of galaxy stellar population properties derived from broad-band SED-fitting - such as age, stellar mass, dust reddening, etc. - on a variety of parameters, such as SFHs, metallicity, IMF, dust reddening…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Janine Pforr , Claudia Maraston , Chiara Tonini

We present a new method for the evaluation of the age and age-spread among pre-main-sequence (PMS) stars in star-forming regions in the Magellanic Clouds, accounting simultaneously for photometric errors, unresolved binarity, differential…

Astrophysics of Galaxies · Physics 2015-05-19 Nicola Da Rio , Dimitrios A. Gouliermis , Mario Gennaro

Spectra of late-type stars are usually analyzed with static model atmospheres in local thermodynamic equilibrium (LTE) and a homogeneous plane-parallel or spherically symmetric geometry. The energy balance requires particular attention, as…

Astrophysics · Physics 2009-11-06 Carlos Allende Prieto , Paul S. Barklem , Martin Asplund , Basilio Ruiz Cobo

Using 17 chemical elements as a proxy for stellar DNA, we present a full phylogenetic study of stars in the solar neighbourhood. This entails applying a clustering technique that is widely used in molecular biology to construct an…

Astrophysics of Galaxies · Physics 2017-03-22 Paula Jofre , Payel Das , Jaume Bertranpetit , Robert Foley

High-resolution galaxy spectra encode information about the stellar populations within galaxies. The properties of the stars, such as their ages, masses, and metallicities, provide insights into the underlying physical processes that drive…

The correlation between [Mg/Fe] and galaxy mass found in elliptical galaxies sets a strong constraint on the duration of star formation. Furthermore, the colour-magnitude relation restricts the range of ages and metallicities of the stellar…

Astrophysics · Physics 2009-11-07 I. Ferreras , J. Silk

The age-metallicity relation is fundamental to study the formation and evolution of the disk. Observations have shown that this relation has a large scatter which can not be explained by observational errors only. That scatter is hence…

Astrophysics of Galaxies · Physics 2021-10-20 Paula Jofre

We present a method to build a probability density function (pdf) for the age of a star based on its peculiar velocities $U$, $V$ and $W$ and its orbital eccentricity. The sample used in this work comes from the Geneva-Copenhagen Survey…

Solar and Stellar Astrophysics · Physics 2018-01-31 Felipe Almeida-Fernandes , Helio Jaques Rocha-Pinto

The age and chemical composition of the stars in present-day galaxies carry important clues about their star formation processes. The latest generation of population synthesis models have allowed to derive age and stellar metallicity…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 Anna Gallazzi