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The Giant Star Ca II Ionization Problem: Mass Loss Revisited

Published online by Cambridge University Press:  26 May 2016

Graham M. Harper
Affiliation:
Center for Astrophysics and Space Astronomy, University of Colorado, Boulder, CO 80309-0389, USA
Alexander Brown
Affiliation:
Center for Astrophysics and Space Astronomy, University of Colorado, Boulder, CO 80309-0389, USA
Thomas Ayres
Affiliation:
Center for Astrophysics and Space Astronomy, University of Colorado, Boulder, CO 80309-0389, USA
Stuart A. Sim
Affiliation:
Imperial College London, Blackett Laboratory, UK

Abstract

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Pioneering studies of winds from non-coronal evolved late-type stars were plagued by uncertainties in the Ca ionization balance which severely limited the accuracy of derived mass-loss rates. Here we re-examine the Ca II ionization balance in these stellar winds using FUSE spectra which reveal, for the first time, the flux from the photoionizing radiation field shortward of 1045Â. We present a FUSE 912-1185Â spectroscopic survey of evolved late-K and M stars; including the M giants α Cet (M1.5 III), γ Cru (M3.5 III), β Gru (M4.5 III), and R Dor (M8e III). Using FUSE spectra of α Tau (K5 III), supplemented with partial redistribution calculations of H Ly-α and Ly-β, together with UV and radio data, we present a study of α Tau's wind ionization balance and derive new constraints which place the mass-loss rate significantly below that suggested by the Reimers formula.

Type
Part 11: Open Magnetic Structures and Winds
Copyright
Copyright © Astronomical Society of the Pacific 2004 

References

Bedding, T. R., Robertson, J. G., & Marson, R. G. 1994, A&A, 290, 340.Google Scholar
Bedding, T. R., et al. 1997, MNRAS, 286, 957.Google Scholar
Dupree, A. K. & Brickhouse, N. S. 1998, ApJ, 500, L33.Google Scholar
Harper, G. M., et al. 2001, ApJ, 551, 486.Google Scholar
McMurry, A. D. 1999, MNRAS, 302, 37.Google Scholar
Mozurkewich, D., et al. 1991, AJ, 101, 2207 VIII, 369.CrossRefGoogle Scholar
Reimers, D. 1977, A&A, 57, 395.Google Scholar
Robinson, R. D., Carpenter, K. G., & Brown, A. 1998, ApJ, 503, 396.Google Scholar
Shine, R. A., & Linsky, J. L. 1974, Sol. Phys. 39, 49.Google Scholar
Sim, S. A. 1999, MNRAS, 326, 821.CrossRefGoogle Scholar