  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.
