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D.A. Leahy, T. Wenwu (University of Calgary)
The supernova remnant HB3 was re-observed at 408MHz and 1420MHz with the Dominion Radio Astrophysical Observatory Synthesis Telescope as part of the Canadian Galactic Plane Survey. These observations supercede previous observations, as they have higher sensitivity and significantly improved calibration and dynamic range.
HB3 is adjacent to the bright HII regions W3, W4 and W5, so that the improved imaging significantly improves the contamination by the HII regions' emission. The current analysis includes identification and removal of background point sources to improve the measurement of the radio flux due to the supernova remnant. Spectral index is measured for several region in HB3 using integrated flux. We also apply the T-T plot method, which is sensitive to the spectral index of spatially variable emission. The results are compared with previously published values. The analysis shows that removal of background point sources and the contribution from extended emission from W3 are both important. The average spectral index of HB3 is 0.3-0.4, flatter than previously reported. The difference is consistent with being due the spectrum of the background sources. The filamentary emission from HB3 is found to have spatially variable spectral index. The possible mechanisms for this are discussed.
This work supported by the Natural Sciences and Engineering Research Council of Canada.
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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.