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Astron. Astrophys. 340, 579-592 (1998)

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4. Conclusion

We have rederived the basic theory of resonance scattering for an incident radiation partially directive and frequency-dependent, the moving scattering atoms having an anisotropic distribution of velocities. We have shown that the three first Stokes parameters of the reemitted line are sensitive to the three components of the macroscopic velocity field. Therefore the interpretation of these Stokes parameters may offer a method for deriving the complete velocity field vector. The formalism is general and be applied to a variety of astrophysical problems where anisotropies of resonance scattering occur.

Then we have applied the formalism to the two-level atom and we have given the expression of the Stokes parameters of the O vi 103.2 nm line of the solar corona formed in the solar wind acceleration region. This line which has a Doppler profile is formed by resonance scattering of the same line originating from the transition region and which has also a Doppler profile. The first numerical results of this formalism have been given by Sahal-Bréchot et al. (1992b) and Sahal-Bréchot & Choucq-Bruston (1994). They will be analysed and discussed in the next paper, in view of future interpretation of solar data obtained by Sumer-Soho.

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© European Southern Observatory (ESO) 1998

Online publication: November 9, 1998