Formation of the hydrogen Lyman alpha line in expanding spherical planetary nebulae.
Abstract
The radiation field in the hydrogen Lymanalpha line is calculated for an optically thick nebula, which is in uniform or accelerated expansion (velocity increasing to the surface). The radiativetransfer equation is solved for a spherical configuration using the discrete space theory with partial redistribution. The computations were performed for a nebula with a ratio of outer to inner radius of 3.3 and an optical depth at line center of about 1000. Velocities up to 26 km/s are considered. In all cases strongly asymmetric profiles are found with a high emission peak at the red side of the line center and a low one at the blue side. Inside the nebula the mean intensities are much smaller than in the static case. The calculations also show that the transverse velocity gradients induced by the sphericity are very important.
 Publication:

Astronomy and Astrophysics
 Pub Date:
 January 1979
 Bibcode:
 1979A&A....71..289W
 Keywords:

 H Lines;
 Lyman Alpha Radiation;
 Planetary Nebulae;
 Radiative Transfer;
 Emission Spectra;
 Flow Velocity;
 Radial Velocity;
 Astrophysics;
 Lyman Alpha:Planetary Nebulae;
 Planetary Nebulae:Expansion;
 Planetary Nebulae:Models;
 Planetary Nebulae:Radiative Transfer