Deriving the Scale Height of the Warm Ionized Medium

Type Conference Paper
Names Matthew Miller, B. Wakker
Proceedings Title Bulletin of the American Astronomical Society
Conference Name American Astronomical Society, AAS Meeting #215, #415.08
Volume 42
Pages 262
Date January 1, 2010
URL http://adsabs.harvard.edu/abs/2010AAS...21541508M
Library Catalog NASA ADS
Abstract The volume density of the warm ionized medium decreases (approximately) exponentially with height above the galactic plane. In this study, we determined the scale height of the warm ionized medium in the Milky Way by analyzing FeIII absorption lines along different lines of sight to targets inside the Milky Way as well as extragalactic targets. In order to determine the column density along a particular line of sight, our primary technique was to integrate the apparent optical depth of FeIII absorption lines. Other techniques included a linear conversion from an FeIII curve of growth and applying FeII curve of growth line widths to FeIII. We also adopted a patchiness parameter (σp) first introduced by Savage (1990) as well as a chi-squared minimization procedure in order to derive the scale height and midplane density of the WIM. We derived the scale height, midplane density and patchiness parameter for the WIM to be H = 0.9 (+/- 0.2) (kpc), no = 3.27 x 10-8 (cm-3), and σp = 0.14. "This work was supported by the National Science Foundation's REU program and the Department of Defense's ASSURE program through NSF Award AST-0453442"
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