[Previous] | [Session 47] | [Next]
S. Sallmen, C.M. Johns-Krull, B. Welsh, N. Griffiths (UC Berkeley)
Classical T Tauri stars (CTTS) are solar mass pre-main sequence stars actively accreting material from a circumstellar disk. The naked T Tauri stars (NTTS) are similarly young stars which lack a close circumstellar accretion disk and appear to derive their activity from dynamo generated magnetic fields. Accretion onto the surface of CTTS is expected to produce shocks reaching temperatures of 106 K, while magnetic activity on both CTTS and NTTS should produce transition region material at 105 K. We present FUSE spectra of the CTTS AS 292 and the NTTS TWA 5A. Both stars show substantial emission in typical transition region lines, while AS 292 shows several additional emission features not seen in the NTTS. Combining these FUSE data with archival IUE data, we will compare our spectra of AS 292 with emissions predicted from various accretion shock models in order to constrain basic quantities including the pre-shock density and velocity of the accreting material. Finally, we note that while AS 292 shows prominent H2 Lyman band emission lines in IUE spectra, no H2 emission is detected in our FUSE spectra. We discuss the implications of this in terms of limits on the temperature of the molecular material and temporal variability.