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G.J. Madsen, R.J. Reynolds, L.M. Haffner (Univ. of Wisconsin - Madison)
We have used the Wisconsin H-Alpha Mapper (WHAM) to investigate the properties of faint, large-scale H\alpha-emitting filaments in the warm ionized medium of the Galaxy. The recent WHAM Northern Sky Survey has revealed several of these remarkable features, some of which may extend over 1 kpc above the Galactic plane. In an effort to understand the origin and physical conditions of these structures, we have obtained optical emission line spectra toward a collection of filaments in H\alpha, H\beta, [\ion{N}{2}], [\ion{S}{2}], \ion{He}{1}, and [\ion{O}{3}]. These filaments include a 60\circ-long vertical structure which rises above the CMa R1 OB association in the plane, a horizontal feature that stretches 20\circ perpendicular to this larger filament, and an isolated filament extending 5\circ near the Lockman window at high Galactic latitude. The temperature, density, extinction, kinematics, and ionization state of these filaments, as revealed by their spectra, is discussed. We also compare the physical conditions within these filaments to classical \ion{H}{2} regions and speculate on their origin.
This work has been supported by the National Science Foundation through grant AST 96-19424.
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The author(s) of this abstract have provided an email address for comments about the abstract: madsen@astro.wisc.edu
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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.