T Tauri stars in the SuperWASP and NSVS surveys II. Spectral modelling

We present results from long-term spectroscopic monitoring of 21 T-Tauri stars located in the Taurus-Auriga star-forming region (SFR). We combine medium and high-dispersion Echelle spectroscopy obtained at the Stara Lesna, Skalnate Pleso (both in Slovakia), and Tautenburg (Germany) observatories with low-resolution flux-calibrated spectra from Asiago (Italy) observatory all taken between 2015 and 2018. We extend the coverage by additional medium-resolution spectra from Star ' a Lesn ' a obtained in 2022. In the previous paper, we measured photometric periods of these targets in a range of 0.7-3.1 d, which could be due to the rotation of a spotted surface or binarity. Here, we use the broadening-function technique to determine the radial and projected rotational velocities to reveal any close binary companion. Our analysis concludes that no such companion is present with an orbital period equal to the photometric period. We focus our analysis primarily on determining atmospheric parameters such as surface gravity log g, effective temperature T-eff, and metallicity [Fe/H]. Additionally, we measure the equivalent width of H alpha, Li I, and interstellar Na I lines. We also investigate the effect of possible reddening on individual targets and construct the HR diagram of our sample. Using pre-main-sequence evolutionary models, we determine the age of our targets. This analysis hints at ages younger than 50 Myr with mean age 5 +/- 3 Myr, masses between 0.75 and 2.10 M-circle dot, and minimum radii in the range 0.60-3.17 R-circle dot. Altogether, the results are consistent with expected young stars with larger radii than those of main-sequence stars.

Automated summary

This study presents the results of long-term spectroscopic monitoring of 21 T-Tauri stars in the Taurus-Auriga star-forming region. The analysis reveals no close binary companion and provides information about atmospheric parameters, age, mass, and radius of the stars. The findings indicate that these stars are young with ages younger than 50 Myr, average age of 5±3 Myr, mass between 0.75 and 2.10 M-circle dot, and minimum radii in the range 0.60-3.17 R-circle dot.