http://bear.ras.ucalgary.ca/magdalen/home/CASCA95_pol_ab.html (Einblicke ins Internet, 10/1995)We have made sensitive observations of a low-level distribution of thermal electrons around the HII regions W3, W4, and W5, detected via the Faraday rotation effects induced in the polarised background of Galactic synchrotron radiation seen through this magneto-ionic screen. We present 1-arcmin resolution polarimetric images at 1420MHz spanning a 9-degree by 6-degree region encompassing W3/4/5 (centred near l=134.7, b=+1.2), observed as the pilot project for the Galactic Plane Survey now underway at the Dominion Radio Astrophysical Observatory. Several new, remarkable phenomena have been identified in these polarisation images; these are as yet imperfectly understood, but provide fascinating clues to the structure of the interstellar medium and magnetic fields in and around this HII complex.
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