Rotation Effects in Classical T Tauri Stars

TL;DR

This study investigates the rotational modulation and angular velocities of classical T Tauri stars, revealing new rotation periods, the distinction between observed and true rotation periods, and the relationship between angular momentum and stellar luminosity.

Contribution

The paper provides new rotation periods for six CTTS, clarifies the difference between brightness variation periods and true rotation periods, and analyzes angular velocity trends across different stellar evolutionary stages.

Findings

Six new rotation periods for CTTS identified.

Brightness variation periods are not always the true rotation periods.

Faster rotation observed in CTTS on radiative tracks.

Abstract

Surface temperature inhomogeneities in classical T Tauri stars (CTTS) induced by magnetic activity and mass accretion lead to rotational modulation of both photometric and spectroscopic parameters of these stars. Using the extended photometric catalogue by Grankin et al. (2007), we have derived the periods and amplitudes of the rotational modulation of brightness and color for 31 CTTS; for six of them, the periods have been revealed for the first time. The inclinations of the rotation axis and equatorial rotational velocities of CTTS have been determined. We show that the known periods of brightness variations for some of the CTTS are not the axial rotation periods but are the Keplerian periods near the inner boundary of the dusty disk. We have found that the angular velocity of CTTS with a mass of 0.3 - 3 M_sun in the Taurus-Auriga complex remains constant in the age range 1 - 10 Myr. CTTS on radiative evolutionary tracks rotate faster than completely convective CTTS. The specific angular momentum of CTTS depends on the absolute luminosity in the H\alpha- line.