The Exteme Ultraviolet Spectrum of Alpha Aurigae (Capella)

A.K. Dupree (1), N.S. Brickhouse (1), G.A. Doschek (2), J.C. Green (3), and J.C. Raymond (1)

1) Harvard-Smithsonian Center for Astrophysics , 60 Garden St., Cambridge, MA 02138
2) Naval Research Laboratory, Washington, DC 20375
3) CASA, University of Colorado, Boulder, CO 80309

Astrophysical Journal Letters,418, L41, 1994.

Abstract

Extreme ultraviolet spectra (70-740 Å) of the bright spectroscopic binary system Capella (Alpha Aurigae), obtained with the Extreme Ultraviolet Explorer satellite (EUVE), show a rich emission spectrum dominated by iron emission lines: Fe XV-XXIV. The emission measure for the system reveals a continuous distribution of plasma temperatures between 1E+05 and 1E+7.8 K, with a clear minimum near 1E+06 K and a local maximum at 6E+06 K. Electron density diagnostics based on Fe XXI indicate N_e ~ 4E+11 to 1E+13 cm-3 at T_e = 1E+07 K.

Subject headings: stars: chromosphere - stars: giant - stars: mass loss - stars: individual (Alpha Aurigae)

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