The Hanle effect and the determination of magnetic fields in solar prominences
Résumé
The object of this paper is to investigate whether the determination of magnetic fields based on the interpretation of the linear polarization modified by the Hanle effect of the He I D3 line in quiescent prominences can be accurate and safe enough. It is shown that the observed depolarization and rotation of the vector polarization result only from magnetic effects. An account of the quantum theory used (a more detailed account will be published separately) for the calculations is given. The interpretation of the attached theoretical polarization diagrams, their use for the determination of magnetic fields, the limitations of the theory and the accuracy of the results are discussed. From this it can be concluded that the present method is very promising, especially for the weak magnetic fields (1-15 Gauss) which are typical of most quiescent prominences.