Atomic Fluorescence and Prospects for Observing Magnetic Geometry Using Atomic Magnetic Realignment

Abstract

Yan and Lazarian have proposed a new technique through which the magnetic field geometry in the diffuse interstellar medium, or in circumstellar matter, could be determined from the linear polarization of interstellar absorption or fluorescence emission lines from ions pumped by an anisotropic illuminating flux. New long-slit spectroscopic observations of the reflection nebula NGC2023, obtained with the Southern African Large Telescope Robert Stobie Spectrograph (RSS), have detected a number of atomic fluorescence lines of OI, NI, SiII, and FeII for the first time in a neutral medium. A model which predicts these lines and others illustrates which lines would be appropriate targets for an RSS spectropolarimetric investigation of this new diagnostic.