Rigorous treatment of the radiative transfer problem in stellar winds - Significance of the velocity law and the chromosphere in the H-alpha profile

1993 ◽  
Vol 411 ◽  
pp. 874 ◽  
Author(s):  
Lydia S. Cidale ◽  
Adela E. Ringuelet
Keyword(s):  
Radiative Transfer ◽  
Transfer Problem ◽  
Stellar Winds ◽  
Radiative Transfer Problem ◽  
Rigorous Treatment

scholarly journals The 12C/13C Ratio in Interstellar Dark Clouds

1980 ◽  
Vol 87 ◽  
pp. 411-416
Author(s):  
W.H. Mccutcheon ◽  
R. L. Dickman ◽  
W.L.H. Shuter ◽  
R. S. Roger
Keyword(s):  
Radiative Transfer ◽  
Interstellar Medium ◽  
Stellar Evolution ◽  
Transfer Problem ◽  
Abundance Ratio ◽  
Radiative Transfer Problem ◽  
Dark Clouds ◽  
Non Equilibrium

Since 13C is believed to be produced by non-equilibrium CNO processing in stellar evolution (Truran 1977), measurements of the carbon ratio Rc ≡ [12C] / [13C] in the interstellar medium may provide important information on nucleo-synthesis. Commonly, the ratio (N13/N18)LTE ≡ [13CO/C18O]LTE is measured and from this RLTE ≡ [12CO/13CO]LTE is deduced and these values are often identified with Rc. However, this line of reasoning can be misleading for two reasons (Dickman et al. 1979):(1) The difficulty of determining accurate column densities, [13C16O] and [12C18O], because of the complexity of the radiative transfer problem;(2) The possible role of fractionation, whereby RCO ≡ [12CO] / [13CO] does not necessarily reflect the initial atomic abundance ratio RC (Watson et al. 1976, Langer 1977, Liszt 1978).

scholarly journals Discontinuities in numerical radiative transfer

2019 ◽  
Vol 622 ◽  
pp. A162 ◽  
Author(s):  
Gioele Janett
Keyword(s):  
Radiative Transfer ◽  
Transfer Equation ◽  
Radiative Transfer Equation ◽  
Transfer Problem ◽  
Stellar Atmospheres ◽  
Physical Parameters ◽  
Radiative Transfer Problem ◽  
Intermittent Behavior ◽  
High Order Convergence ◽  
Magnetohydrodynamic Simulations

Observations and magnetohydrodynamic simulations of solar and stellar atmospheres reveal an intermittent behavior or steep gradients in physical parameters, such as magnetic field, temperature, and bulk velocities. The numerical solution of the stationary radiative transfer equation is particularly challenging in such situations, because standard numerical methods may perform very inefficiently in the absence of local smoothness. However, a rigorous investigation of the numerical treatment of the radiative transfer equation in discontinuous media is still lacking. The aim of this work is to expose the limitations of standard convergence analyses for this problem and to identify the relevant issues. Moreover, specific numerical tests are performed. These show that discontinuities in the atmospheric physical parameters effectively induce first-order discontinuities in the radiative transfer equation, reducing the accuracy of the solution and thwarting high-order convergence. In addition, a survey of the existing numerical schemes for discontinuous ordinary differential systems and interpolation techniques for discontinuous discrete data is given, evaluating their applicability to the radiative transfer problem.

scholarly journals Comparison of parallel eigensolvers for a discretized radiative transfer problem

PAMM ◽  
2007 ◽  
Vol 7 (1) ◽  
pp. 1022805-1022806 ◽  
Author(s):  
P. B. Vasconcelos ◽  
O. A. Marques
Keyword(s):  
Radiative Transfer ◽  
Transfer Problem ◽  
Radiative Transfer Problem

scholarly journals The 2D continuum radiative transfer problem

2004 ◽  
Vol 417 (3) ◽  
pp. 793-805 ◽  
Author(s):  
I. Pascucci ◽  
S. Wolf ◽  
J. Steinacker ◽  
C. P. Dullemond ◽  
Th. Henning ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Transfer Problem ◽  
Radiative Transfer Problem
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