POSTER PAPER 5.06
Dynamics of Coronal Iron Lines in Cool Stars Based on FUSE and HST/STIS Observations
Seth Redfield, Thomas R. Ayres, Jeffrey L. Linsky, Edward F. Guinan
Institute: JILA, University of Colorado
Institute: CASA, University of Colorado
Institute: NIST
Institute: Department of Astronomy and Astrophysics, Villanova University
Contact Email: sredfield@astro.as.utexas.edu
Abstract:
We present UV observations of coronal forbidden lines of highly ionized iron. Fe XXI Lambda 1354 and Fe XII Lambda 1242 have been observed by spectrographs on board the Hubble Space Telescope (HST), and Fe XVIII Lambda 975 recently has been identified in spectra taken by the Far Ultraviolet Spectroscopic Explorer (FUSE). Mass motions of hot gas in the corona provide information on the heating mechanism and magnetic field strength in the corona. Observations of forbidden iron lines with these moderate to high resolution spectrographs provide a unique opportunity to study high temperature dynamics of the hot coronal plasmas. We positively detect the forbidden iron line of Fe XVIII Lambda 975 in five stars. Beta Ceti shows the strongest Fe XVIII emission, and since it is a single star system, it is an ideal target to study stellar coronal dynamics. We find that the hot coronal plasma is confined, in contrast to observed downflows at the temperatures where the 105 K lines like C III Lambda 977 form.
Index Keywords: Beta Cet
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Manuscript submitted: 2001-Sep-05
"The Future of Cool-Star Astrophysics", 2003, Eds. A. Brown,
G. M. Harper, & T. R. Ayres.
Proceedings of 12th Cambridge Workshop on Cool Stars, Stellar Systems,
& The Sun,
© 2003 University of Colorado.