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Paper: New Analysis of Magnetic Field Using Gaia DR2 Catalog and Cepheids in the Galactic Plane
Volume: 528, New Horizons in Galactic Center Astronomy and Beyond
Page: 319
Authors: Zenko, T.; Nagata, T.; Kurita, M.; Kino, M.; Nishiyama, S.; Matsunaga, N.; Nakajima, Y.
Abstract: A new method for measuring the global magnetic field structure of the Galactic plane is presented. We derive the distances of 52 Cepheids (d > ∼ 10 kpc) and surrounding nearby field stars in the Galactic plane, using the period-luminosity relations of the Cepheids and the Gaia DR2 catalog, respectively. Polarimetric observations were made with the SIRPOL attached to the 1.4m telescope IRSF for the 52 Cepheid fields. Then, division of the field stars in each line of sight into a) foreground, b) bulge, and c) background is made with the Gaia DR2 catalog, the peak of the H–KS color histogram, and H–KS colors consistent to be as distant as the Cepheid in the center, respectively. We calculate the average KS-band polarization of the nearby foreground, the bulge, and the distant stars in the 52 field of views and then calculate differential polarization from the observer to the distant stars. We can divide the 52 fields into 3 types from the behavior of the differential polarization. The sightlines which show well aligned magnetic fields in the Galactic plane is rather small in number, and many of the 52 fields show that random magnetic field components are significant.
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