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Related papers: Towards Better Age Estimates for Stellar Populatio…

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We present a new set of isochrones in which the effect of the alpha-element enhancement is fully incorporated. These isochrones are an extension of the already published set of YY Isochrones (Yi et al. 2001: Paper 1), constructed for the…

Astrophysics · Physics 2010-04-06 Yong -Cheol Kim , Pierre Demarque , Sukyoung K. Yi , David R. Alexander

A new grid of theoretical isochrones based on the Yale stellar evolution code using the OPAL and Kurucz opacities has been constructed. The grid of isochrones spans a wide range of metallicities, helium abundances and masses. The…

We present four large sets of evolutionary tracks for stars with initial chemical compositions [Y=0.250, Z=0.008], [Y=0.273, Z=0.019], [Y=0.320, Z=0.040] and [Y=0.390, Z=0.070] and enhancement of alpha elements with respect to the solar…

Astrophysics · Physics 2007-05-23 Bernardo Salasnich , Leo Girardi , Achim Weiss , Cesare Chiosi

We present new evolutionary stellar models suitable for old Population I clusters, discussing both the consequences of the most recent improvements in the input physics and the effect of element diffusion within the stellar structures.…

Astrophysics · Physics 2009-10-31 V. Castellani , S. Degl'Innocenti , M. Marconi

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]…

Solar and Stellar Astrophysics · Physics 2015-06-22 Don A. VandenBerg , Peter A. Bergbusch , Jason W. Ferguson , Bengt Edvardsson

One of the largest sources of uncertainty in the computation of globular cluster isochrones and hence in the age determination of globular clusters is the lack of a rigorous description of convection. Therefore, we calibrated the…

Astrophysics · Physics 2009-10-31 Bernd Freytag , Maurizio Salaris

The first paper in this series explored the effects of altering the chemical mixture of the stellar population on an element by element basis on stellar evolutionary tracks and isochrones to the end of the red giant branch. This paper…

Recent analyses of solar spectroscopic data (see Asplund, Grevesse & Sauval 2004 and references therein) suggest a significative variation of the heavy elements abundance. The change of heavy mixture might affect the determination of the…

Astrophysics · Physics 2007-05-23 S. Degl'Innocenti , P. G. Prada Moroni , B. Ricci

[Abridged] We present a large, new set of stellar evolution models and isochrones for an alpha-enhanced metal distribution typical of Galactic halo and bulge stars; it represents a homogeneous extension of our stellar model library for a…

Astrophysics · Physics 2011-09-30 A. Pietrinferni , S. Cassisi , M. Salaris , F. Castelli

In view of the important contributions of red giants to the integrated light in evolutionary synthesis calculations of old stellar populations in clusters and galaxies, we provide a comparison of theoretical isochrones computed from the…

Astrophysics · Physics 2007-05-23 T. Lejeune , R. Buser

The ages of star clusters and co-moving stellar groups contain essential information about the Milky Way. Their special properties make them excellent tracers of galactic structure and key components to unlocking its star formation history.…

Astrophysics of Galaxies · Physics 2024-10-02 Alena Rottensteiner , Stefan Meingast

We present new stellar population models, $\alpha$-MC, self-consistently taking into account non-solar $\rm [\alpha/Fe]$ abundances for both isochrones and stellar spectra. The $\alpha$-MC models are based on $\alpha$-enhanced MIST…

Astrophysics of Galaxies · Physics 2024-10-30 Minjung Park , Charlie Conroy , Benjamin D. Johnson , Joel Leja , Aaron Dotter , Phillip A. Cargile

Stellar evolution calculations with variable abundance ratios were used to gauge the effects on temperatures, luminosities, and lifetimes in various phases. Individual elements C, N, O, Mg, Si, and Fe were included. Most of the effect…

Astrophysics of Galaxies · Physics 2022-02-09 Guy Worthey , Xiang Shi , Tathagata Pal , Hyun-chul Lee , Baitian Tang

The Gaia mission has provided highly accurate observations that have significantly reduced the scatter in the colour-magnitude diagrams of open clusters. As a result of the improved isochrone sequence of the open cluster M67, we have…

Solar and Stellar Astrophysics · Physics 2024-07-09 Claudia Reyes , Dennis Stello , Marc Hon , Regner Trampedach , Eric Sandquist , Marc Pinsonneault

We present the result of our investigation on the impact of the low Solar abundance of Asplund and collaborators (2004) on the derived ages for the oldest star clusters based on isochrone fittings. We have constructed new stellar models and…

Solar and Stellar Astrophysics · Physics 2015-05-19 Sukyoung K. Yi , Yong -Cheol Kim

The ACS Survey of Galactic Globular Clusters, an HST Treasury Project, will deliver high quality, homogeneous photometry of 65 globular clusters. This paper introduces a new collection of stellar evolution tracks and isochrones suitable for…

Astrophysics · Physics 2010-11-05 A. Dotter , B. Chaboyer , D. Jevremovic , E. Baron , J. W. Ferguson , A. Sarajedini , J. Anderson

This is the fourth paper of our new release of the BaSTI (a Bag of Stellar Tracks and Isochrones) stellar model and isochrone library. Following the updated solar-scaled, alpha-enhanced, and white dwarf model libraries, we present here…

We present a large and updated stellar evolution database for low-, intermediate- and high-mass stars in a wide metallicity range, suitable for studying Galactic and extragalactic simple and composite stellar populations using population…

Astrophysics · Physics 2009-11-10 A. Pietrinferni , S. Cassisi , M. Salaris , F. Castelli

Globular clusters (GCs) provide statistically significant coeval populations of stars spanning various evolutionary stages, allowing robust constraints on stellar evolution model parameters and ages. We analyze eight old Milky Way GCs with…

Astrophysics of Galaxies · Physics 2025-05-07 Jiaqi , Ying , Brian Chaboyer , Michael Boylan-Kolchin , Daniel Weisz , Rowan Goebel-Bain

The Yale stellar evolution code has been modified to use the OPAL equation of state tables (Rogers 1994). Stellar models and isochrones were constructed for low metallicity systems ($-2.8 \le [Fe/H] \le -0.6$). Above $M\sim 0.7\,\msun$, the…

Astrophysics · Physics 2009-10-28 Brian Chaboyer , Yong --Cheol Kim
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