Abstract
view Abstract Citations (35) References (52) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Evolution of chromospheres and coronae in solar mass stars : a far-ultraviolet and soft X-ray comparison of Arcturus (K2III) and alf CEN A (G2V). Ayres, T. R. ; Simon, T. ; Linsky, J. L. Abstract IUE far-UV and Einstein Observatory soft X-ray observations for the red giant Arcturus and the nearby yellow dwarf Alpha-Centauri A, which are archetypes of solar mass stars in different stages of evolution, are compared. Evidence is found for neither coronal soft X-ray emission from the red giant, at surface flux levels of only 0.0006 that detected previously for the yellow dwarf, nor C II and IV resonance line emission at surface flux levels of only 0.02 those of the yellow dwarf. The resonance line upper limits and previous detections of the C II intersystem UV multiplet 0.01 near 2325 A provide evidence for an Arcturus outer atmosphere that is geometrically extended, tenuous and cool. The red giant has, in addition, a prominent cool stellar wind. An extensive tabulation of line identifications, widths and fluxes for the IUE far-UV echelle spectra of the two stars is given, and two competing explanations for the Wilson-Bappu effect are discussed. Publication: The Astrophysical Journal Pub Date: December 1982 DOI: 10.1086/160549 Bibcode: 1982ApJ...263..791A Keywords: Chromosphere; Far Ultraviolet Radiation; Red Giant Stars; Stellar Coronas; Stellar Evolution; X Ray Sources; Iue; Line Spectra; Radiant Flux Density; Resonance Lines; Spectral Line Width; Stellar Mass; Stellar Winds; Ultraviolet Spectra; X Ray Spectra; Astrophysics full text sources ADS | data products SIMBAD (2) MAST (1) INES (1)
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