Magnetically active stars in Taurus-Auriga: Photometric variability and basic physical parameters

We have analyzed homogeneous long-term photometric observations of 28 well-known weakline T Tauri stars (WTTS) and 60 WTTS candidates detected by the ROSAT observatory toward the Taurus-Auriga star-forming region. We show that 22 known WTTS and 39 WTTS candidates exhibit periodic light variations that are attributable to the phenomenon of spotted rotational modulation. The rotation periods of these spotted stars lie within the range from 0.5 to 10 days. Significant differences between the long-term photometric behaviors of known WTTS and WTTS candidates have been found. We have calculated accurate luminosities, radii, masses, and ages for 74 stars. About 33% of the sample of WTTS candidates have ages younger than 10 Myr. The mean distance to 24 WTTS candidates with reliable estimates of their radii is shown to be 143 ± 26 pc. This is in excellent agreement with the adopted distance to the Taurus-Auriga star-forming region.