T Tauri stars in the SuperWASP and NSVS surveys II. Spectral modelling
Authors:
L. Hambalek, V. Krushevska, T. Pribulla, M. Vanko, J. Budaj, M. Fiorucci, Z. Garaj, E. Guenther, R. Komzik, E. Kundra, U. Munari and B. Smalley
Image & caption:
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Image caption::
HR diagram for our sample stars. Blue solid lines show evolutionary tracks for stars of different solar masses (indicated by the number crossing a particular line), and red solid lines are isochrones for a given age in millions of years (indicated by a number crossing a particular isochrone). Evolutionary data from Pisa Stellar models (Tognelli et al. 2011) for metallicity [Z = 0.006, Y = 0.26].
Description:
Based on the previous photometric study of 21 selected stars classified as young T Tauri stars (with conflicting information in the literature) in the Taurus-Auriga association (constellations of Taurus and the Chariot), we researched their spectra. We used telescopes in Stará Lesna, Skalanté Pleso, but also TLS Jena (Germany), and Asiago (Italy). On the obtained spectra, we modeled the atmospheres of the selected stars - primarily their effective temperature, surface gravity, and metallicity. We specifically investigated lithium lines 6708 and 6104 as indicators of young age. According to them and their temperatures, all the studied stars are young (up to 50 million years) and mostly similar to the Pleiades. The older ones border the main sequence as the so-called post-T Tauri stars. We also determined a high rotation speed and checked whether they were spectroscopic binaries. We independently came across HD 283447, which is often not even treated in the literature but is a quadruple star. Likewise, HD 30171 shows signs of multiplicity. From proper movements and the radial velocity determined by us, we verified that all objects move in the same way as the average of the Taurus-Auriga association. We calculated the corrected luminosity of the objects from the parallax from the Gaia satellite and constructed the HR diagram. Using evolutionary models, we estimated the age and mass of the stars. We got the radii from the rotation velocity and the previously determined period thanks to the speckled surface. All results were consistent with young rapidly rotating stars with radii larger than their respective spectral type and masses between 0.75 and 2.1 solar masses.
Reference:
Monthly Notices of the Royal Astronomical Society, 524, 3582-3595 (2023)
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