GHRS Spectra of $\alpha$~Tau
Session 45 -- Stellar Activity I
Display presentation, Tuesday, 10, 1995, 9:20am - 6:30pm

## [45.09] GHRS Spectra of $\alpha$~Tau

K. Carpenter (LASP/NASA-GSFC), R. Robinson (CSC@LASP/NASA-GSFC), P. Judge (HAO/NCAR)

Goddard High Resolution Spectrograph (GHRS) observations of the K5 giant $\alpha$~Tau were obtained on 8 April 1994. Spectra of approximately 40~\AA-wide regions centered near 1300, 1550, 1660, 1995, 2340, 2760, and 2800 \AA\ were obtained through the Small Science Aperture (SSA) with medium resolution (R=20,000) gratings. These data provide high-precision profiles of a variety of lines formed in the stellar chromosphere and transition region, including O~I, Fe~II, C~I, C~II], Si~II], Mg~II, and C~IV. Self-reversed emission from O~I, Fe~II, and Mg~II provide information on the wind flow velocities, with all three ions showing both red and blue-shifted absorption components, as seen previously in the Fe~II emission from the later-type giants $\gamma$~Cru and $\mu$~Gem. The first evidence for hot plasma in the outer atmosphere of $\alpha$~Tau is seen in the G160M spectrum centered near 1550~\AA\@. This spectrum shows very broad, but distinct features due to the C~IV (UV~1) doublet, as well as a myriad of much narrower emissions formed at cooler temperatures, such as (fluorescent) Fe~II and perhaps Ni~II and C~I. C~I (UV~2) is seen in emission and a comparison of its flux with that in C~I (UV~32) will allow an estimation of the C~I chromospheric column density. Multiple observations of the C~II] (UV~0.01) intercombination multiplet were obtained to search for evidence of shocks and/or propagating waves. Results of that search will be presented. Finally, very high-resolution (R=85,000) echelle spectra were obtained of the Mg~II resonance doublet near 2800~\AA\@. These emission features show strong interstellar, stellar, and circumstellar absorption components at, above, and below the stellar rest velocity.