The Yale–Potsdam Stellar Isochrones

Abstract

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 accurate low-mass models (M * < 0.6 M ⊙ ), and in particular of their mass-luminosity and mass-radius relations, both crucial in characterizing exoplanet-host stars and, in turn, their planetary systems. The YaPSI models cover the mass range 0.15 to 5.0 M ⊙ , densely enough to permit detailed interpolation in mass, and the metallicity and helium abundance ranges [Fe/H] = −1.5 to +0.3, and Y 0 = 0.25 to 0.37, specified independently of each other (i.e., no fixed ∆Y /∆Z relation is assumed). The evolutionary tracks are calculated from the pre-main sequence up to the tip of the red giant branch. The isochrones, with ages between 1 Myr and 20 Gyr, provide UBVRI colors in the Johnson-Cousins system, and JHK colors in the homogeneized Bessell & Brett system, derived from two different semi-empirical T eff -color calibrations from the literature. We also provide utility codes, such as an isochrone interpolator in age, metallicity, and helium content, and an interface of the tracks with an open-source Monte Carlo Markov-Chain tool for the analysis of individual stars. Finally, we present comparisons of the YaPSI models with the best empirical massluminosity and mass-radius relations available to date, as well as isochrone fitting of well-studied stellar clusters.

The ancient main-sequence solar proxy HIP 102152 unveils the activity and rotational fate of our Sun

“…Based on these values, we estimate that HIP 102152 will reach Ro = 1 in less than 0.5 Gyr from now (according to the models used in LO19), a negligible age interval that makes it statistically within the expected region of basal flux dominance. In brief, LO19 built P rot tracks from modified Kawaler windlaw and YaPSI models (Spada et al 2017). LO19 assumed the dominance of structural effects over magnetic braking terms whenever the star approaches into the turn-off region or a given Rossby number (Ro crit ), leaving only the moment of inertia to drive the subsequent P rot evolution.…”

Magnetic fields of intermediate mass T Tauri stars

“…The stellar masses have been estimated with the luminosities and effective temperatures from the litterature, using the Yale-Potsdam Stellar Isochrones grid (Spada et al 2017). The two-component model performs significantly better at reproducing the shape of the Fe i line at 15648.5 Å.…”

The open cluster King 1 in the second quadrant

“…The age, distance modulus and reddening are traditionally derived by over-imposing isochrones to the ob- Spada et al 2017). In all the cases we assumed a solar metallicity (see Section 6).…”