Photometric Variability Properties of 21 T Tauri and Related Stars From AAVSO Visual Observations

Volume 38 number 2 (2010)

John R. Percy

Samantha Esteves

Jou Glasheen

Alfred Lin

Junjiajia Long

Marina Mashintsova

Abstract

T Tauri variables are sun-like stars in various stages of their birth. We have analyzed long-term AAVSO visual observations of 21 T Tauri and related stars, using Fourier and self-correlation techniques. This follows our previous study of eleven such stars in JAAVSO 35, 290 (2006). Only a few of the variables showed periodic behavior, but self-correlation analysis makes it possible to construct a "variability profile" - amount of variability versus time scale - for all the stars, not just the periodic ones. For some of the periodic variables, we have studied the long-term behavior of the periods and amplitudes: T Cha and HT Lup appear to be rotating variables with stable periods less than 10 days; RU Lup, UX Ori, and TU Phe appear to show transient cycles of typically 50-500 days, probably arising in the accretion disc. R CrA has a stable 66-day period, which would be unusually long for a rotation period; its cause is not clear. We also discuss interesting but spurious low-amplitude one-year and one-month periodicities which occur in a few of the stars. Finally: we comment on the star AQ Dra, an RR Lyrae star, originally classified as a T Tauri star with a 5.5-day period.