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R.I. Baker (ETSU), L.M. Haffner, R.J. Reynolds, G.J. Madsen (UW-Madison)
We have used the Wisconsin H\alpha Mapper (WHAM) to obtain velocity-resolved maps in H\alpha, [S II] \lambda 6716, and [N II] \lambda 6583 of the ionized gas surrounding the well-known O9.5V star zeta Ophiuchi. Line ratio maps of [S II]/H\alpha and [N II]/H\alpha increase away from the center of the classical H II region. The [S II]/[N II] ratio remains fairly constant throughout the nebula. Variations in line-intensity ratios can originate from changes in the ionization states of the elements or a change in the temperature of the gas. To investigate which might be dominant in this region, we derive and construct a map of the temperature and non-thermal velocity throughout the entire nebula. By decomposing the total line widths into their thermal and non-thermal components, we find clear spatial trends of these parameters within the nebula. The temperature throughout the nebula increases from approximately 6000K at the center to 8000K at the edge of the H II region. The non-thermal velocity map reveals a decrease in velocity from about 8 km s-1 to 4 km s-1 from the center to the edge of the H II region. The results obtained from this diffuse H II region around zeta Oph can be compared to studies of the Warm Ionized Medium (WIM) to provide important insight into the nature of the diffuse ionized gas seen above the plane and in the halo of the Galaxy. This research was funded by the NSF sponsored Research Experience for Undergraduates (REU) program at the University of Wisconsin-Madison. WHAM is supported by NSF grant AST 02-04973.
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The author(s) of this abstract have provided an email address for comments about the abstract: baker@astro.wisc.edu
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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.