Spicule-dominated coronae and late-type giant evolution

Abstract

view Abstract Citations (6) References (22) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Spicule-dominated coronae and late-type giant evolution Wallenhorst, S. G. Abstract The mass-loss rates and coronal temperatures of stars that have evolved away from the main sequence are examined, using an energy-balance model in which the coronal energy losses due to hot, downflowing spicular material are included. It is postulated that the coronal energy input flux remains constant as a star evolves up the red giant branch. Stable solutions for a corona of this type are found to exist only below a critical stellar radius. The locus of these radii on the H-R diagram is identified with the Temperature Dividing Line (TDL) of Linsky and Haisch (1979). If the total energy input flux has the assumed value of 1.3 x 10 to the 6th ergs/sq cm-s, then this constant-flux approach yields results which are consistent with the predictions of the minimum flux corona theory of Hearn (1979). It is shown that several criticisms of the theory are valid for minimum flux models in which spicular downflow is neglected, but are satisfied by the models considered. As a star evolves across the TDL, a jump in mass-loss rate of a factor of about 3 is expected. Publication: The Astrophysical Journal Pub Date: October 1981 DOI: 10.1086/159273 Bibcode: 1981ApJ...249..176W Keywords: Late Stars; Red Giant Stars; Spicules; Stellar Coronas; Stellar Evolution; Stellar Mass Ejection; Chromosphere; Energy Dissipation; Hertzsprung-Russell Diagram; Stellar Models; Stellar Temperature; Astrophysics full text sources ADS |