K. E. RANGARAJAN
Articles written in Journal of Astrophysics and Astronomy
Volume 2 Issue 1 March 1981 pp 81-86
Photon escape probabilities in expanding atmospheres
A. Peraiah K. E. Rangarajan D. Mohan Rao
A comparison of mean number of scatterings and escape probabilities has been made in isotropic scattering and dipole scattering by using the angle-averaged partial frequency redistribution function
We find that the partial frequency redistribution gives a larger mean number of scatterings compared to that given by complete redistribution. Velocities tend to reduce the mean number of scatterings and in crease the mean escape probabilities.
Volume 2 Issue 3 September 1981 pp 245-252
Effects of redistribution with dipole scattering on line source functions
The partial frequency redistribution function for zero natural line width with dipole scattering (R_{I}) has been considered in obtaining the simultaneous solution of the statistical equilibrium and line transfer equations in the comoving frame of the expanding gas. We have considered a non-LTE two level atom in an expanding spherical medium whose outer radii are 3, 10 and 20 times the stellar radius with a total optical depth
Volume 5 Issue 2 June 1984 pp 169-180
Effects of partial frequency redistribution functions R_{II}, R_{III} and R_{V} on source functions
D. Mohan Rao K. E. Rangarajan A. Peraiah
The effects of partial frequency redistribution on the formation of spectral lines have been studied. We considered the angle-averaged R_{II}, R_{III} and
Volume 21 Issue 3-4 September 2000 pp 269-269
Parametric study of molecular line polarization in the solar atmosphere
Volume 41 All articles Published: 24 March 2020 Article ID 0010
H$\alpha$ full line spectropolarimetry as diagnostics of chromospheric magnetic field
K. NAGARAJU K. SANKARASUBRAMANIAN K. E. RANGARAJAN
Analysis of spectropolarimetric observations of two circular sunspots located close to disk centre in H$\alpha$ (6562.8 Å) and Fe i (6569.22 Å) is presented in this paper. The corresponding active region numbers areNOAA 10940 and NOAA 10941 referred to as AR1 and AR2, respectively. The vector magnetic field at the photosphere is derived through inversion of Stokes profiles of Fe I under Milne–Eddington atmospheric model. The chromospheric vector magnetic field is derived from H$\alpha$ Stokes profiles under weak-field approximation. Azimuthally averaged magnetic field as a function of radial distance from the centre of sunspot at the photosphere and chromosphere are studied. At the photosphere, the radial variation shows a well known behaviour that the total field and the line-of-sight (LOS) component monotonically decrease from centre to the edge of the sunspot and the transverse component initially increases, reaches a maximum close to half the sunspot radius and thendecreases. LOS and the transverse components become equal close to half the sunspot radius consistent with the earlier findings. At the chromosphere, all the components of the magnetic field decrease with the sunspot radius. However, the LOS component decreases monotonically whereas the transverse component decreases monotonically up to about 0.6 times the sunspot radius after which it reaches a constant value. Azimuthally averaged magnetic field gradient from photosphere to chromosphere is also presented here.
Volume 43, 2022
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