The Effect of Redistribution on the Emission Peaks from Chromospheric-type Stellar Atmospheres
Abstract
Summary. The equation of transfer for spectral line radiation is solved for a physically idealistic model problem involving departures from complete redistribution. In particular, we consider a two-level atom one- dimensional atmosphere exhibiting a chromospherictype temperature rise, and compute emergent absorption line profiles having emission peaks similar to those observed in the core of Ca II and Mg ii H and K lines. We also include a macroscopic velocity field, and show that the corresponding emergent line profiles computed assuming complete redistribution are markedly different to those obtained using the angle-averaged redistribution function for the case of pure Doppler broadening with isotropic scattering (i.e. in Hummer's, 1962 notation). In some cases, for example, the emission peaks obtained using complete redistribution disappear altogether when using Rr , and thus we conclude that the effects of general must be taken into account when analysing spectral `lines of this type. Key words: redistribution - line profile - emission peaks - chromosphere
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- April 1974
- Bibcode:
- 1974A&A....32...85C