Serendipitous XMM-Newton Detection of X-ray Emission from the Bipolar Planetary Nebula Hb 5
This is the pre-print of an article published by the American Astronomical Society. The final, published version is available here: https://doi.org/10.1088/0004-637X/694/2/1481
© 2009 The American Astronomical Society.
Also archived in: arXiv:0901.4095v1 [astro-ph.SR]
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Abstract
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.
