Open AccessStellar evolution models for Z = 0.0001 to 0.03
Author(s) -
Pols Onno R.,
Schro¨der KlausPeter,
Hurley Jarrod R.,
Tout Christopher A.,
Eggleton Peter P.
Publication year - 1998
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.1998.01658.x
Subject(s) - physics , metallicity , mixing (physics) , astrophysics , helium , stellar evolution , diffusion , convection , lagrangian , hydrogen , code (set theory) , statistical physics , stars , thermodynamics , atomic physics , theoretical physics , quantum mechanics , set (abstract data type) , computer science , programming language
We have calculated a grid of empirically well tested evolutionary tracks with masses M between 0.5 and 50 M⊙, spaced by approximately 0.1 in log M , and with metallicities Z = 0.0001, 0.0003, 0.001, 0.004, 0.01, 0.02 and 0.03. We use a robust and fast evolution code with a self‐adaptive non‐Lagrangian mesh, which employs the mixing‐length theory but treats convective mixing as a diffusion process, solving simultaneously for the structure and the chemical composition. The hydrogen and helium abundances are chosen as functions of the metallicity: X = 0.76 − 3.0 Z Y = 0.24 + 2.0 Z . Two sets of models were computed, one without and one with a certain amount of enhanced mixing or ‘overshooting’. This amount has been empirically chosen by means of various sensitive tests for overshooting: (1) the luminosity of core helium burning (blue loop) giants of well‐known mass, (2) the width of the main sequence as defined by double‐lined eclipsing binaries with well‐measured masses and radii, and (3) the shape and implied stellar distribution of isochrones of various open clusters. The first two tests have been the subject of previous papers, the third test is discussed in this paper. On the basis of these tests, we recommend the use of the overshooting models for masses above about 1.5M ⊙. We describe here the characteristics of the models, the procedure for constructing isochrones for arbitrary age and metallicity from the models, and the performance of these isochrones for several intermediate‐age and old open clusters. All original models are available in electronic form and we describe the means by which they may be obtained.