Theoretical Line Intensities. VII. Wavelength and Depth Dependence of Line-Blanketing Effects for Pure Absorption and Non-Coherent Scattering

Abstract

view Abstract Citations (13) References (14) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Theoretical Line Intensities. VII. Wavelength and Depth Dependence of Line-Blanketing Effects for Pure Absorption and Non-Coherent Scattering Athay, R. Grant ; Skumanich, A. Abstract The processes involved in line blanketing are investigated in detail for a two-level atom whose spectral line is formed partially in pure absorption and partially in non-coherent scattering (non-LTE). Line and continuum interactions are included through absorption of line photons by continuum processes, and vice versa. Interactions with the thermal energy of particles are included through collisional excitations and de-excitations. Calculations of the "local" blanketing effect, designated by e, are made for lines of different equivalent widths, in different spectral regions, and for different absorption profiles. We consider an atmosphere in which B(r) is linear. In general, such an atmosphere is not in radiative equilibrium and requires mechanical energy to maintain the assumed temperature profile even if no lines are present in the spectrum. If lines are added to the spectrum without distorting B(r), the local energy requirements are changed by an amount e and the total energy (per unit area) is changed by an amount E = J'edr. For a Milne-Eddington (M-E) atmosphere in pure absorption (LTE) and linear B(r), E is shown to be positive (mechanical energy must be added to the atmosphere) and equal to the flux "blocked" out by the equivalent widths of the lines, »=W~H~c. In the corresponding case for a Schuster-Schwarzschild (S-S) atmosphere, just the reverse is true, E = - ~ and energy must be removed from the atmos- phere to preserve the linear B(r). In the limiting case of an isothermal atmosphere in LTE, E -p 0 for the M-E atmosphere. When scattering (non-LTE) is present for a M-E atmosphere, E is the same as for LTE for saturated lines in all spectral regions, while it is approximately the same for iøisaturated lines in the violet and visual spectral regions. In the case of the S-S atmosphere, the LTE result for the integrated blanketing remains unchanged. However, in both cases the local LTE and non-LTE blanketing effects as given by e differ appreciably, mainly in the degree of thermal cooling at the boundary. Equations derived to express the self-consistent (radiative equilibrium) problem provide, we believe, more accurate and numerically more tractable calculations of the blanketed temperature profile Publication: The Astrophysical Journal Pub Date: January 1969 DOI: 10.1086/149864 Bibcode: 1969ApJ...155..273A full text sources ADS | Related Materials (7) Part 1: 1965ApJ...142..724A Part 2: 1965ApJ...142..732A Part 3: 1965ApJ...142..755A Part 4: 1966ApJ...144.1159A Part 5: 1966ApJ...145..784A Part 6: 1968ApJ...152..211A Part 8: 1969ApJ...157..281A