Serendipitous XMM-Newton Detection of X-ray Emission from the Bipolar Planetary Nebula Hb 5

Rodolfo Montez Jr, Rochester Institute of Technology
Joel H. Kastner, Rochester Institute of Technology
Bruce Balick, University of Washington
Adam Frank, University of Rochester

This is the pre-print of an article published by the American Astronomical Society. The final, published version is available here:

© 2009 The American Astronomical Society.

Also archived in: arXiv:0901.4095v1 [astro-ph.SR]

Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works in February 2014.


We report the serendipitous detection by the XMM-Newton X-ray Observatory of an X-ray source at the position of the Type I (He- and N-rich) bipolar planetary nebula Hb 5. The Hb 5 X-ray source appears marginally resolved. While the small number of total counts (~170) and significant off-axis angle of the X-ray source (~7.8') precludes a definitive spatial analysis, the morphology of the X-ray emission appears to trace the brightest features seen in optical images of Hb 5. The X-ray spectrum is indicative of a thermal plasma at a temperature between 2.4 and 3.7 MK and appears to display strong Neon emission. The inferred X-ray luminosity is L_X = 1.5 x 10^32 ergs/s. These results suggest that the detected X-ray emission is dominated by shock-heated gas in the bipolar nebula, although we cannot rule out the presence of a point-like component at the position of the central star. The implications for and correspondence with current models of shock-heated gas in planetary nebulae is discussed.