Faraday rotation is a process by which the position angle (PA) of background linearly polarized light is rotated when passing through an ionized and magnetized medium. The effect is sensitive to the line-of-sight magnetic field in conjunction with the electron density. This contribution highlights diagnostic possibilities of inferring the magnetic field (or absence thereof) in and around wind-blown bubbles from the Faraday effect. Three cases are described as illustrations: a stellar toroidal magnetic field, a shocked interstellar magnetic field, and an interstellar magnetic field within an ionized bubble.
Richard Ignace. "Faraday Rotation Effects for Diagnosing Magnetism in Bubble Environments." ASTRA Proceedings 1.1 (2014): 1-5. doi:10.5194/ap-1-1-2014
Available at: http://works.bepress.com/richard_ignace/81