GHRS Spectra of the Active Chromosphere Binary V711~Tau (HR~1099)
Session 5 -- Chromospheres/Coronae/Active Binaries
Display presentation, Monday, 30, 1994, 9:20-6:30

[5.14] GHRS Spectra of the Active Chromosphere Binary V711~Tau (HR~1099)

Robert C. Dempsey (STScI), James E. Neff (Penn. State), Jeffrey L. Linsky (JILA)

During a multiwavelength campaign in September of 1993 a unique array of telescopes was directed at the chromospherically-active binary system V711~Tau (HR~1099) in an effort to determine fundamental properties of a late-type stellar atmosphere from the photosphere to the corona. Observations of the RS~CVn system V711~Tau were obtained with the HST, IUE, VLA, and EUVE observatories. In addition, ground-based optical spectroscopy and photometry were obtained with the APT in Phoenix and at Penn State's Black Moshannon Observatory. We present preliminary results from GHRS observations obtained at 5 phases over 2.5 stellar rotations. GHRS spectra of Mg~II~h \& k (2796, 2830~\AA)\ and the C~IV doublet (1548,1550~\AA)\ are used to probe the chromosphere and transition regions of the K1~IV star, while electron density diagnostics are extracted from the Si~III] (1892~\AA)\ and C~III] (1909~\AA)\ intersystem lines. Additional spectra of the 2600~\AA\ region and H~I Lyman-$\alpha$ spectral regions were obtained at one quadrature phase. Although phase coverage is poor, we are able to extract limited information on temporal and/or spatial variability of the system. Changes in line flux and profile shape are observed in several lines including a variation of approximately 60\% in the Si~III]/C~III] ratio. Finally, since V711 Tau has been observed extensively by IUE over the past 16 years, the HST data provide a high resolution benchmark for this larger body of data.