by Jennifer Lauer
Under the supervision of Professor Len Kuhi
Echelle spectra of the extreme T Tauri star RW Aurigae have been taken during ninety-one nights, over six years by G. Basri at Lick Observatory. Current models predict that the H$\alpha$ and Ca II infrared triplet lines form in different temperature regions of the star; simultaneous monitoring of these lines will therefore provide some information on how these different regions interact with one another. We have used the H_alpha and Ca II lines to compare these formation regions.
The Ca II emission line in RW Aur is too broad to be formed solely in
the chromosphere of the star, as is usually predicited for T Tauri stars.
The wings of this line reach out to ~ ±400 km/sec, which is much
faster than normal chromospheric motions. We therefore look at other possible
regions of formation for the line, such as the turbulent envelope that surrounds
the star, or jets from the system. To help facilitate this, we have broken
down the Ca II emission in to three components represented by gaussians.
When we do this, we can identify two high-velocity components, centered
at ~ ±100 km/sec, and a component that is centered close to the stellar
velocity. The gaussian centered at ~ ± 0 km/sec can be tentatively
identified as formed in the chromosphere of the star or a turbulent envelope
surrounding the system, while the two higher-velocity components might be
formed in jets or outflow from the star. If this identification of the
formation regions is correct, then the observed variability that is seen
in both the H_alpha and the Ca II line would indicate that a large portion
of the emission lines are being formed in the same region.