AAS 198th Meeting, June 2001
Session 41. The Milky Way Galaxy
Display, Tuesday, June 5, 2001, 10:00am-6:30pm, Exhibit Hall

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[41.05] The Structure of the Galactic Magnetic Field as Revealed by Starlight Polarimetry

J. M. Walawender, E. G. Zweibel (University of Colorado at Boulder), C. Heiles (University of California at Berkeley)

We present the results of an observational study of the local galactic magnetic field probed by the polarization of starlight. Using a least-squares fitting technique we derive the local direction and curvature of the uniform component of the galactic magnetic field. We find a local direction of l\circ = 80.6\circ, a radius of curvature, Rcc = 7.8 kpc, and the position of the center of curvature to be lcc = -15.4\circ, which are roughly consistent with the structure of the spiral arms of the Galaxy and with the earlier results of Heiles 1996.

We also probe the structure of the turbulence in the field and attempt to measure its amplitude and correlation length. Both density and magnetic field fluctuations affect the distribution of polarization. We present simulations which demonstrate the extent to which the two can be separated and use the observations to place constraints on the nature of the magnetic fluctuation spectrum.

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