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Session 48 - Spiral & Field Galaxies.
Display session, Tuesday, January 16
North Banquet Hall, Convention Center

[48.13] ROSAT HRI Observations of NGC 2276 and NGC 1961

D. S. Davis, W. C. Keel (U. Alabama), J. S. Mulchaey (OCIW), J. J. Condon (NRAO)

Results from the analysis of the NGC 2276 and NGC 1961 ROSAT HRI will be presented. For NGC 2276, a spiral with disk diameter about 2 arcmin, the HRI data show that the strong star-forming knots on the western, truncated side of the disk are also strong X-ray sources. Furthermore, diffuse disk emission is detected as well, this is by far most distant spiral in which this component has been measured. The diffuse disk emission accounts for \sim2.1\times10^41 erg s^-1 out of the galaxy's total of \sim3.5\times10^41 erg s^-1 in the HRI X-ray band. This luminosity is not unusual for bright spirals, but the long exposure of this observation allows its detection at an unusual distance. NGC 1961 is a spiral galaxy which also shows distorted optical morphology similar to that seen in NGC 2276. The HRI image is clearly extended, with diffuse emission from the disk but no bright X-ray emission from the brightest star-forming regions (in contrast to the structure of NGC 2276). Cross-correlation of the X-ray image with data from the radio continuum, optical continuum, and H\alpha, to isolate the contributions related to recent star formation as traced in these bands, and a search for any link required to influences of the surrounding IGM will also be presented.

Program listing for Tuesday