Revising the ages of planet-hosting stars

TL;DR

This study measures the ages of planet-hosting stars using stellar models and compares two age determination methods, revealing a broader age distribution with some stars younger than previously thought.

Contribution

Introduces and applies two algorithms for stellar age estimation, highlighting limitations and providing revised age distributions for planet-hosting stars.

Findings

Approximately 6% of stars are younger than 0.5 Gyr.

The age distribution peaks between 1.5 and 2 Gyr.

About 7% of stars are older than 11 Gyr.

Abstract

This article aims to measure the age of planet-hosting stars (SWP) through stellar tracks and isochrones computed with the \textsl{PA}dova \& T\textsl{R}ieste \textsl{S}tellar \textsl{E}volutionary \textsl{C}ode (PARSEC). We developed algorithms based on two different techniques for determining the ages of field stars: \emph{isochrone placement} and \emph{Bayesian estimation}. Their application to a synthetic sample of coeval stars shows the intrinsic limits of each method. For instance, the Bayesian computation of the modal age tends to select the extreme age values in the isochrones grid. Therefore, we used the isochrone placement technique to measure the ages of 317 SWP. We found that $\sim6\%$ of SWP have ages lower than 0.5 Gyr. The age distribution peaks in the interval [1.5, 2) Gyr, then it decreases. However, $\sim7\%$ of the stars are older than 11 Gyr. The Sun turns out to be a common star that hosts planets, when considering its evolutionary stage. Our SWP age distribution is less peaked and slightly shifted towards lower ages if compared with ages in the literature and based on the isochrone fit. In particular, there are no ages below 0.5 Gyr in the literature.