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Related papers: The OPAL Equation of State and Low Metallicity Iso…

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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…

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

We have constructed a new set of isochrones, called the Y^2 Isochrones, that represent an update of the Revised Yale Isochrones (RYI), using improved opacities and equations of state. Helium diffusion and convective core overshoot have also…

Astrophysics · Physics 2011-07-18 S. Yi , P. Demarque , Y. -C. Kim , Y. -W. Lee , C. Ree , Th. Lejeune , S. Barnes

Based on the work of OPAL (Iglesias & Rogers 1996) and Alexander & Ferguson (1994), we construct a series of opacity tables for various metallicities Z=0, 0.00001, 0.00003, 0.0001, 0.0003, 0.001, 0.004, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06,…

Astrophysics · Physics 2009-11-11 Xuefei Chen , Christopher A. Tout

Hubble Space Telescope (HST) fine guidance sensor observations were used to obtain parallaxes of eight metal-poor ([Fe/H] < -1.4) stars. The parallaxes of these stars determined by the revised Hipparcos reduction average 17% accuracy, in…

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

Stellar evolutionary tracks for $0.12 \le M/M_\odot \le 1.0$ have been computed for each of several variations in the abundances of C, N, and O, assuming mass-fraction helium abundances $Y = 0.25$ and $0.29$, and 11 metallicities in the…

Solar and Stellar Astrophysics · Physics 2022-11-30 Don A. VandenBerg

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

We perform an extensive test of theoretical stellar models for main-sequence stars in ugriz, using cluster fiducial sequences obtained in the previous paper of this series. We generate a set of isochrones using the Yale Rotating…

We introduce the Yale-Potsdam Stellar Isochrones (YaPSI), a new grid of stellar evolution tracks and isochrones of solar-scaled composition. In an effort to improve the Yonsei-Yale database, special emphasis is placed on the construction of…

Solar and Stellar Astrophysics · Physics 2017-04-12 F. Spada , P. Demarque , Y. -C. Kim , T. S. Boyajian , J. M. Brewer

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

An extensive grid of metal-rich isochrones utilizing the latest available input physics has been calculated for comparison with the old, metal-rich open cluster NGC 6791. The isochrones have been simultaneously fit to BV and VI color…

Astrophysics · Physics 2009-10-31 Brian Chaboyer , Elizabeth M. Green , James Liebert

We present stellar evolutionary models covering the mass range from 0.4 to 1 Msun calculated for metallicities Z=0.020 and 0.001 with the MHD equation of state (Hummer & Mihalas, 1988; Mihalas et al. 1988; D\"appen et al. 1988). A parallel…

Astrophysics · Physics 2009-10-31 C. Charbonnel , W. Dappen , D. Schaerer , P. A. Bernasconi , A. Maeder , G. Meynet , N. Mowlavi

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

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

We have developed an homogeneous evolutionary scenario for H- and He-burning low-mass stars by computing updated stellar models for a wide metallicity and age range (0.0002$\le Z \le$0.004 and 9$\le t(Gyr) \le$15, respectively) suitable to…

Astrophysics · Physics 2009-11-07 F. Caputo , S. Cassisi

Main sequence turn-off (MSTO) stars are good tracers of Galactic populations since their ages can be reliably estimated from atmospheric parameters. Based on the GALAH survey, we use the Yale Rotation Evolution Code to determine ages of…

Solar and Stellar Astrophysics · Physics 2022-04-27 Xunzhou Chen , Zhishuai Ge , Yuqin Chen , Shaolan Bi , Jie Yu , Wuming Yang , Jason W. Ferguson , Yaqian Wu , Yaguang Li

From an initial sample of a few hundred stars selected for an Hipparcos program, a subsample of 33 objects with direct determination of their effective temperature, bolometric magnitude and [Fe/H] has been derived. An accurate observational…

Astrophysics · Physics 2007-05-23 Y. Lebreton , M. -N. Perrin , R. Cayrel , A. Baglin , J. Fernandes

Using the code AUTOSTRUCTURE, extensive calculations of inner-shell atomic data have been made for the chemical elements He, C, N, O, Ne, Na, Mg, Al, Si, S, Ar, Ca, Cr, Mn, Fe and Ni. The results are used to obtain up-dated opacities from…

We create isochrones of M67 using the Yale Rotating Stellar Evolution Code. In addition to metallicity, parameters that are traditionally held fixed, such as the mixing length parameter and initial helium abundance, also vary. The amount of…

Solar and Stellar Astrophysics · Physics 2017-11-08 Lucas S. Viani , Sarbani Basu
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