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Session 6 - HII Regions & Massive Star Formation.
Display session, Wednesday, January 07
As part of a long-term investigation into the distribution of dust within evolved galactic HII regions, calibrated H-alpha images have been obtained of the objects M20 (= S30, the Trifid Nebula), S106, and NGC 7538 (= S158). Observations were made with an Axiom/Apogee 2048x2048 CCD camera attached to the 0.9-m telescope operated by the Southeastern Association for Research in Astronomy (SARA) at Kitt Peak National Observatory. Each object was observed with a narrow-band (0.3 nm) H-alpha filter as well as with a 10-nm wide filter centered at 645.7 nm in order to remove the contribution of continuum emission from the H-alpha images. Flux calibration was performed by observation of planetary nebulae for which calibrated spectrophotometry has been published. Comparison of the resulting H-alpha contour maps with published radio continuum maps permits determination of the distribution of obscuring dust within each nebula. Future H-beta observations will be used to prepare contour maps of the reddening within each nebula, which will in turn provide insight into variations of grain properties within HII regions.
This research is supported by grants from the National Science Foundation Research Experience for Undergraduates program and from the American Astronomical Society.
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