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Chromospheres and Winds of Cool Stars

Published online by Cambridge University Press:  30 March 2016

Kenneth G. Carpenter*
Affiliation:
Laboratory for Astronomy and Solar Physics Code 681, NASA – Goddard Space Flight CenterGreenbelt, MD 20771

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I present data acquired during the early operations era of the HST with the Goddard High Resolution Spectrograph (GHRS) on three late-type giant and supergiant stars: α Tau (K5 III non-coronal), λ Dra (K5 III hybrid), and α Ori (M2 lab). Figure 1 shows fits to echelle (R=100,000) line profiles of three ions seen in the spectrum of α Tau. The Co II line can be fit with a single gaussian, the self-reversed Fe II line with a combination of an emission and absorption gaussian, but the unreversed C II lines require two emission gaussians of substantially different FWHM and maxima. The complex shape of the C II profiles suggests that the turbulent velocity distribution in the chromosphere is anisotropic (e.g. Gray 1988) or that the lines are formed in two regions characterized by significantly different Teff and Vturb, as in the hybrid star models of Harper (1991).

Type
Joint Discussions
Copyright
Copyright © Kluwer 1992

References

1 Brown, A. and Jordan, C. 1980, M.N.R.A.S., 191, 37P.Google Scholar
2 Carpenter, K. G. 1991, in Cool Stars, Stellar Systems, and the Sun, in press.Google Scholar
3 Gray, D. F. 1988, chap. 1 in Lectures on spectral Line Analysis: F, G., and K Stars, (The Publisher: Arva, Ontario).Google Scholar
4 Harper, G. 1991, M.N.R.A.S., submitted.Google Scholar