Abstract
We have investigated the effects of increasing optical depths on spectral lines formed in a rotating and expanding spherical shell. We have assumed a shell whose outer radius is 3 times the inner radius, with the radial optical depths equal to 10, 50, 100, 500. We have employed a constant velocity with no velocity gradients in the shell. The shell is assumed to be rotating with velocities varying as 1/ρ, whereρ is the perpendicular distance from the axis of rotation, implying the conservation of angular momentum. Two expansion (radial) velocities are treated: (1)V = 0 (static case) and (2)V = 10 mean thermal units. The maximum rotational velocities areV rot = 0, 5, 10 and 20. In the shell where there are no radial motions, we obtain symmetric lines with emission in the wings forV rot = 0 and 5 while forV rot ≥ 10 we obtain symmetric absorption lines. In the case of an expanding shell, we obtain lines with central emission.
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References
Mihalas, D. 1978,Stellar Atmospheres, 2nd edn, Freeman, San Francisco.
Peraiah, A. 1980,.J. Astrophys. Astr.,1, 17 (Paper I).
Slettebak, A. 1979,Space Science Rev.,23, 541.
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Peraiah, A., Raghunath, G. & Nagendra, K.N. Optical depth effects on the formation of spectral lines in rotating and expanding spherical atmospheres. J Astrophys Astron 2, 277–284 (1981). https://doi.org/10.1007/BF02714552
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DOI: https://doi.org/10.1007/BF02714552