Evolutionary Status of T Tauri Stars

TL;DR

This study evaluates various pre-main sequence evolutionary models for T Tauri stars, finding good mass estimates for stars above 0.7 solar masses but significant discrepancies for lower-mass stars, confirming their pre-main sequence status.

Contribution

The paper systematically tests multiple evolutionary models against observational data of binary T Tauri stars, highlighting their accuracy and limitations across different mass ranges.

Findings

Models agree well for stars > 0.7 M_sun with ~10% error.

Significant divergence in isochrones for stars ≤ 0.7 M_sun.

Most T Tauri stars have ages below Kelvin-Helmholtz time.

Abstract

The problem of the determination of T Tauri stars masses and ages using their evolutionary status is discussed. We test of pre-main sequence evolutionary models of D'Antona \& Mazzitelli (1994), Dotter et al. (2008), Bressan et al. (2012) and Chen et al. (2014), Baraffe et al. (2015) using well determined observational parameters of 12 binary T Tauri stars (TTS) and 2 binary red dwarfs. It is shown that the masses derived using the tracks of all models are in good agreement with the masses obtained from the observations of TTS with masses $M > 0.7 M_{\odot}$ (mean error $\varepsilon\sim10\% $). Low-mass stars with $M \le 0.7 M_{\odot}$ have significantly greater mean error: $\varepsilon \sim 50\%$ for the tracks of Bressan et al. and Chen et al. and $\varepsilon \sim 30\%$ for the other tracks. The isochrones of all tested evolutionary models diverge for the stars with masses $M \le 0.7 M_{\odot}$. The difference increases with the mass decrease and can reach 10\% of Kelvin-Helmholtz time for stars with mass $M = 0.2 M_{\odot}$. The ages of most of the considered T Tauri stars are smaller than the Kelvin-Helmholtz time. This confirms their evolutionary status of pre-main sequence stars.