Spectral line formation in non-LTE expanding atmospheres
The local transfer equation is formulated for an optically thick atmosphere in which a linear velocity field is present, in order to obtain an integral equation for the line source function. The study and solution of this equation compared with that for the static case'' makes clear the effect of the shift of the absorption coefftcient, due to the velocity gradient, upon the photons emitted in the line, in the continuum, and coming from the exterior (incident intensity). In some cases, the line source function in presence of a velocity gradient can be greater than in the static case''. The variation of emergent intensity with direction is grenter than in the static case''; consequently the geometric effect produced on the flux by this variation is very important. Emergent intensities and fluxes have also been computed. Some calculated line-profiles have the shape of P Cygni'' or Wolf Rayet'' profiles. On the other hand, quasi-symmetrical lineprofiles have been produced, which can be erroneously attributed to microturbulence'' or rotational broadening. (auth)
- Research Organization:
- Institut d'Astrophysique, Paris
- NSA Number:
- NSA-29-016525
- OSTI ID:
- 4384245
- Journal Information:
- Astron. Astrophys., v. 29, no. 3, pp. 357-367, Other Information: Orig. Receipt Date: 30-JUN-74
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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