The spectral variability of the Classical T Tauri star DR Tau - Astron. J. (2001) 122, 3335 |
Abstract:
We present the analysis of 103 spectra, collected over more than a decade,
of the Classical T Tauri star DR Tau observed with the Hamilton echelle
spectrograph at Lick Observatory. The star exhibits strong emission lines
that show substantial variety and variability in their profile shapes. The
emission lines show signatures of both outflow and infall which vary on
multiple timescales. The system shows quasi-periodic variations in line
intensity and wavelength, but we are unable to recover a unique period that
describes all of the data. The Balmer and He I line changes are well
correlated and appear to result from real variations in the accretion and wind
flows, as opposed to apparent variations caused by changes in the veiling
continuum flux. The Balmer line profiles are generally strongly peaked in the
red (v ~ 100 km/s), and do not resemble published theoretical
magnetospheric accretion profiles. We suggest that the system is seen nearly
pole-on. Coupled with a line emissivity that increases strongly near the
stellar surface, this can explain the strongly asymmetric Balmer line profiles.
The Ca II and He I emission line components are found to be very symmetric
and Gaussian in shape, suggesting production in a turbulent (possibly magnetic)
region. An additional, sporadic, high-velocity outflow component is seen
in the Balmer lines and He I. The main characteristic of the lines is their
dramatic variability, which indicates a very dynamic interaction between the
star and the disk. This is illustrated in several MPEGs showing the line
profile variations of DR Tau which are available on CDROM and at
http://sprg.ssl.berkeley.edu/~cmj/html/drtau.html.
alencar01.pdf - The paper! |