Published in: ApJ, 457, 773.
An X-ray spectrum of a wind-blown bubble in the planetary nebula BD +30 deg3639, acquired by the Advanced Satellite for Cosmology and Astrophysics (ASCA), shows the presence of hot (T = 3 x 106 K) gas dominated by the Ne K alpha line complex. There is circumstantial evidence for the enhanced abundances of other H- and He-burning products, although O is not as abundant as in the extremely C-rich stellar wind of the W-R central star. The temperature of the hot gas is several times lower than expected behind the shock from the 700 km s-1 stellar wind. This might be caused by variations in the stellar wind speed and its chemical abundances induced by the central star evolution, and possibly aided by mixing of the stellar wind gas with the nebular material. Mixing is hinted by the discovery of small (0."2) dusty clumps in the Hubble Space Telescope (HST) narrowband images of the nebula in [S III] lambda 9532 and [O II] lambda 3727 emission lines. These clumps are projected against an axisymmetric, nearly square nebular shell and are most likely associated with the neutral and molecular envelope surrounding the wind-blown bubble and the wind-swept shell.