Mathematics – Logic
Scientific paper
May 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011aas...21811002k&link_type=abstract
American Astronomical Society, AAS Meeting #218, #110.02; Bulletin of the American Astronomical Society, Vol. 43, 2011
Mathematics
Logic
Scientific paper
Planetary nebulae (PNe), the near-endpoints of stellar evolution for intermediate-mass stars, exhibit a dizzying variety of optical/near-infrared morphologies: round; elliptical; bipolar; highly point-symmetric; chaotic and clumpy. The physical mechanisms responsible for this morphological menagerie are hotly debated. It is thought that the shape of a PN results from the sculpting of previously ejected, slow-moving (red giant) stellar envelope material by a fast wind from a (newly unveiled) white dwarf at the PN's core. But to explain the large fraction of nonspherical PNe -- which are presumably shaped by aspherical fast winds -- some models now further propose that many (perhaps most) PNe are the products of interacting binary systems. Chandra is yielding valuable insight into these stellar outflow shaping processes. Chandra imaging spectroscopy of PNe provides a unique means to determine the X-ray surface brightness distributions, temperatures, emission measures, and elemental abundances within the "hot bubbles" generated by fast wind shocks. Chandra observations of PNe have also revealed intriguing examples of unresolved X-ray sources that are too hard to be modeled as photospheric emission from hot white dwarfs. Such hard X-ray point sources are likely indicative of the presence of binary companions and/or accretion processes at PN central stars. I summarize the progress in these areas resulting from Chandra's first dozen years, and present early results from the first systematic Chandra survey of PNe in the solar neighborhood -- a survey designed to understand the formation and evolution of hot bubbles, and to establish the frequency and characteristics of point-like X-ray sources, within PNe with names like the Ring, the Dumbbell, the Owl, and Saturn.
This work is supported by NASA Astrophysics Data Analysis Program and Chandra X-ray Center (CXC) grants to RIT. The CXC is operated by SAO for and on behalf of NASA under contract NAS8-03060.
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