Resonance Line Transfer with Partial Redistribution. V. The Solar CA II Lines

Abstract

view Abstract Citations (89) References (19) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Resonance Line Transfer with Partial Redistribution. V. The Solar CA II Lines Shine, R. A. ; Milkey, R. W. ; Mihalas, Dimitri Abstract Line profiles for the Ca II H and K lines have been calculated, accounting for the partial frequency coherence of scattered photons. These profiles are compared with calculations made with identical atomic and atmospheric models but assuming complete redistribution. Very significant differences between the profiles obtained using these two different physical descriptions of the scattering process are found, and it is now apparent that the assumption of complete redistribution is a serious oversimplification of the actual physical situation. The partial sredistribution (PRD) results are in substantially better agreement with observation than the complete redistribution (CRD) profiles in describing (a) the center-to-limb behavior of the intensity at K1 and K2, (b) the center-to-limb behavior of the wavelength positions of K1 and K2, and (c) the relative behavior of the H and K profiles, as a function of wavelength, at disk center. Further, we find that we may match the observed absolute intensity at K1 with a minimum chromospheric electron temperature of about 4450 K, and that the HSRA temperature minimum is too low when partial redistribution effects are taken into account. This result raises questions about the validity of equating brightness temperatures observed at K1 in stellar spectra with minimum temperatures in stellar chromospheres; it appears likely that such a procedure will systematically underestimate the value of Tmin. Subject headings: chromosphere, solar - line formation - radiative transfer Publication: The Astrophysical Journal Pub Date: August 1975 DOI: 10.1086/153744 Bibcode: 1975ApJ...199..724S full text sources ADS |