The Pisa pre-main sequence tracks and isochrones. A database covering a wide range of Z, Y, mass, and age values

TL;DR

This paper presents an extensive database of updated pre-main sequence stellar models and isochrones across various metallicities, masses, and ages, improving the tools for age and mass determination of young stars.

Contribution

The authors developed a comprehensive set of pre-MS models and isochrones with a wide parameter grid, incorporating recent physical improvements and providing publicly accessible data.

Findings

Models show close agreement with observational data

Updated physics lead to more reliable age and mass estimates

Database covers a broad range of chemical compositions and stellar parameters

Abstract

In recent years new observations of pre-main sequence stars (pre-MS) with Z <= Zsun have been made available. To take full advantage of the continuously growing amount of data of pre-MS stars in different environments, we need to develop updated pre-MS models for a wide range of metallicity to assign reliable ages and masses to the observed stars. We present updated evolutionary pre-MS models and isochrones for a fine grid of mass, age, metallicity, and helium values. We use a standard and well-tested stellar evolutionary code (i.e. FRANEC), that adopts outer boundary conditions from detailed and realistic atmosphere models. In this code, we incorporate additional improvements to the physical inputs related to the equation of state and the low temperature radiative opacities essential to computing low-mass stellar models. We make available via internet a large database of pre-MS tracks and isochrones for a wide range of chemical compositions (Z = 0.0002 - 0.03), masses (M = 0.2 - 7.0 Msun), and ages (1 - 100 Myr) for a solar-calibrated mixing length parameter \alpha (i.e. 1.68). For each chemical composition, additional models were computed with two different mixing length values, namely \alpha = 1.2 and 1.9. Moreover, for Z >= 0.008, we also provided models with two different initial deuterium abundances. The characteristics of the models have been discussed in detail and compared with other work in the literature. The main uncertainties affecting theoretical predictions have been critically discussed. Comparisons with selected data indicate that there is close agreement between theory and observation.