The filling factor of active regions on the surfaces of the dM stars

Abstract

view Abstract Citations (28) References (19) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The filling factor of active regions on the surfaces of the dM stars. Giampapa, M. S. Abstract According to the appearance of the H-alpha line in their spectra, the M dwarf stars are subdivided into two classes, including the dMe stars and the dM stars. Arguments, based on the unique properties of H-alpha line formation in the M dwarf stars, are presented to demonstrate that the surfaces of the dM stars must be characterized by a significant areal coverage (or 'filling factor') of presumably magnetic field-related active regions. In addition, an estimate regarding the lower limit to the filling factor of chromospheric regions on dM stars is obtained, and an empirical relation is provided for the upper limit to the intrinsic Ca II (and Mg II) emission in these stellar surface regions. The discussion utilizes general model results obtained by Cram and Mullan (1979) and Giampapa et al. (1982). Publication: The Astrophysical Journal Pub Date: December 1985 DOI: 10.1086/163744 Bibcode: 1985ApJ...299..781G Keywords: Chromosphere; Dwarf Stars; H Alpha Line; Late Stars; M Stars; Magnetic Stars; Absorption Spectra; Dynamo Theory; Stellar Coronas; Stellar Rotation; Astrophysics full text sources ADS | data products SIMBAD (4)