Ardila, David R.

Contact Email: ardila@astron.berkeley.edu
Institute: Astronomy Department
University of California at Berkeley
First Coauthor: Gibor Basri
Institute: Fred W. Walter
Second Coauthor: Jeff A. Valenti
Institute: Christopher M. Johns-Krull
Presenting Thesis: Yes
Subject Area: Star Formation, Very Young Stars, T-Tauri, H-H Objects
Waveband: Ultraviolet
Technique: Spectroscopy
Presentation: Poster Display
Title: What can High-Resolution UV spectra tell us about T Tauri Stars?
Abstract: We have analyzed GHRS/HST data of eight Classical T Tauri stars (CTTSs) and one Weak T Tauri stars (WTTSs). The GHRS data consists of spectral ranges 40 Å wide centered on 1345, 1400, 1497, 1550, 1900, and 2800 Å. These UV spectra show strong Si IV, C IV, and Mg II emission, and large quantities of sharp (<60 km/s) H2 lines. For 4 of the CTTS we have nearly simultaneous optical observations which contain H$\alpha$, H$\beta$, He II, NaD, and the Ca II IRT. H2 lines are produced by fluorescence by LyAlpha and they may form in the stellar outflow. The populations of their pumping states are not in LTE. We observe strongly blueshifted episodic emission in C IV, perhaps due to magnetic reconnection events in the TTS magnetosphere. In general the CIV and SiIV lines are wide ( 200 km/s) and symmetric. MgII shows evidence of self-reversal absorptions and a strong outflow. Furthermore, its width is similar to the simultaneous Halpha profiles, which implies that the width of H$\alpha$ is not caused by the Stark effect, as has been suggested. We observe evidence of multiple outflows and show that these outflows cannot be spherical.