" Circumstellar Magnetic Field Diagnostics from the Polarization of Line Scattering " AST- 0098597
During the period of the award, a new set of magnetic field diagnostics for dilute astrophysical plasmas will be developed and predictions made which can be followed up observationally. These effects manifest themselves in the polarization of light which has been scattered from the magnetized volumes. Fluorescent scattering of light by atoms causes an observable linear polarization of spectral lines which depends on well-established atomic physics. The new diagnostics could yield the first-ever measurements of magnetic fields in circumstellar envelopes and thus be invaluable to investigations of phenomena involving star-wind coupling with the interstellar medium, comet comae, cool star envelopes and hot stellar winds. The proposed work involves (a) the development of the theory of atomic alignment, (b) new atomic physics calculations for ions of astrophysical interest, and (c) an exploration of the regime where both alignment and polarization effects apply. Broader impacts of the work include the development of cross-disciplinary ties between the solar and stellar physics communities and the development of a potential new diagnostic for dilute plasmas.