Studying the Temperature and Ionization State of the Warm Ionized Medium

Type Conference Paper
Names Melissa Halford, E. J. Mierkiewicz, R. J. Reynolds, G. J. Madsen, L. M. Haffner, K. A. Barger, F. L. Roesler
Conference Name Bulletin of the American Astronomical Society
Volume 43
Pages 25109
Date January 1, 2011
Library Catalog NASA ADS
Abstract Using data from the Wisconsin Hydrogen Alpha Mapper (WHAM) and Pine Bluff Observatory's Spatial Heterodyne Spectrometer (SHS), we studied the warm ionized component of the Galaxy's interstellar medium (WIM). Line ratios of H-alpha, [N II], [O II] and [S II] emission were used to study the WIM gas in both the local spiral arm and more distant areas of the Galaxy. The strength of the [S II] line was used to measure the ionization state in a set of nine look directions and ratios of [N II]/H-alpha and [O II]/H-alpha provide a measure of temperature. Our study expands upon and confirms the results of previous [O II] studies of the WIM, which limited themselves to line ratios including only the local component of the [O II] emission. The work presented here includes a detailed component analysis of WIM emission from non-local gas in the kinematically distinct Perseus spiral arm and uses [S II] data that was not available in the previous [O II] study. This work was supported by the National Science Foundation's REU program through NSF Award AST-1004881. WHAM is funded by the National Science Foundation through grant AST-0607512; the [OII] SHS is funded by the National Science Foundation through grant AST-0908894.
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