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Session 45 - Interstellar Medium I.
Display session, Tuesday, January 16
North Banquet Hall, Convention Center

[45.06] Wide-Field H-alpha Observations of a Possible Galactic Chimney Associated With W4

G. A. Topasna, B. Dennison, J. H. Simonetti (Virginia Tech)

From HI observations, Normandeau, Taylor and Dewdney have identified a possible galactic chimney emanating from W4. We observed a 10\deg--diameter field centered on the chimney in the Balmer-alpha line using a CCD camera sensitive to faint emission. Our observations reveal a pair of wisps diverging from the W4 region, and approximately coincident with the boundaries of the chimney as indicated by the HI void. These wisps can be traced to great distance. They appear to close six degrees (\approx200 pc) from W4 and seven degrees above the galactic plane. These observations lend support to the chimney hypothesis and suggest that we may be seeing the ionized inner surface of a large shell formed by stellar outflows from the W4 region. This research was supported by NSF grant AST-9319670 and a grant from the Horton Foundation to Virginia Tech.

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