Periodic variability in the emission spectrum of T Tauri

Abstract

Context. Long timescale periodic variations in T Tauri stars may be related to changes in their protoplanetary disks.
Aims: A lengthy homogeneous series of spectral observations of the CTTS T TauN has been analyzed.
Methods: We search for periodicity in the equivalent widths of the emission lines in the optical and in the UV.
Results: Significant periodic variation is found in the equivalent widths of Hβ and CaII emission features on a time scale of 33 ± 1.5 days. Variations in the UV emission lines based on archival IUE spectra are also consistent with this period.
Conclusions: This is clearly not the rotation period of the star, which is known to be 2.8 days, and must arise somewhere in the magnetosphere, disk or outflow region.