Stellar model chromospheres. VIII - 70 Ophiuchi A /K0 V/ and Epsilon Eridani /K2 V/

Abstract

view Abstract Citations (57) References (28) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Stellar model chromospheres. VIII. 70 Ophiuchi A (K0 V) and epsilon Eridani (K2 V). Kelch, W. L. Abstract Model atmospheres for the late-type active-chromosphere dwarf stars 70 Oph A and Epsilon Eri are computed from high-resolution Ca II K line profiles as well as Mg II h and k line fluxes. A method is used which determines a plane-parallel homogeneous hydrostatic-equilibrium model of the upper photosphere and chromosphere which differs from theoretical models by lacking the constraint of radiative equilibrium (RE). The determinations of surface gravities, metallicities, and effective temperatures are discussed, and the computational methods, model atoms, atomic data, and observations are described. Temperature distributions for the two stars are plotted and compared with RE models for the adopted effective temperatures and gravities. The previously investigated T min/T eff vs. T eff relation is extended to Epsilon Eri and 70 Oph A, observed and computed Ca II K and Mg II h and k integrated emission fluxes are compared, and full tabulations are given for the proposed models. It is suggested that if less than half the observed Mg II flux for the two stars is lost in noise, the difference between an active-chromosphere star and a quiet-chromosphere star lies in the lower-chromospheric temperature gradient. Publication: The Astrophysical Journal Pub Date: June 1978 DOI: 10.1086/156212 Bibcode: 1978ApJ...222..931K Keywords: Chromosphere; Dwarf Stars; Late Stars; Stellar Atmospheres; Stellar Models; Stellar Spectra; Binary Stars; H Lines; K Lines; Line Spectra; Metallic Stars; Photoionization; Photosphere; Spectrum Analysis; Stellar Mass; Stellar Temperature; Temperature Distribution; Astrophysics; Line Profiles:Stellar Chromospheres; Stellar Chromospheres: Models full text sources ADS | data products SIMBAD (2) Related Materials (12) Part 1: 1973ApJ...180..473L Part 2: 1974ApJ...192...93A Part 3: 1975ApJ...200..660A Part 4: 1975ApJ...201..212A Part 5: 1976ApJ...210..199A Part 6: 1978ApJ...220..619L Part 7: 1978ApJ...220..962K Part 9: 1979ApJ...229..700K Part 10: 1979ApJS...41...47L Part 11: 1979ApJS...41..481L Part 12: 1981ApJ...246..502G Part 13: 1982ApJ...258..740G