Wind Velocity and Density Laws for the Hybrid-Chromosphere Star alpha TrA obtained from GHRS Spectra
We have used the Goddard High Resolution Spectrometer on HST to study the wind of the hybrid-chromosphere star alpha TrA (K2 IIb-IIIa). The stellar wind is detected by the absorption seen against the chromospheric Mg II resonance lines (h and k) centered at 2795.53 Angstroms and 2802.70 Angstroms. Spectra obtained with the high spectral resolution (lambda /Delta lambda =84,750) and low scattered light properties of the GHRS echelle grating reveal stellar Mg II emission lines with complex interstellar absorption and a broad wind absorption feature centered at --90 km s(-1) . We infer the Mg II opacity as a function of velocity and derive velocity laws for the stellar wind by comparing the observed line profiles with synthetic profiles computed for a range of wind parameters. We also discuss the origin of the observed broad lines of Si III], C III], and C IV. This work is supported by NASA Interagency Transfer S-56460-D to the National Institute of Standards and Technology.
American Astronomical Society Meeting Abstracts #184
- Pub Date:
- May 1994