The Asymmetric X-ray Morphologies of Planetary Nebulae
Joel H. Kastner(Chester F. Carlson Center for Imaging Science, Rochester Institute of Technology), Noam Soker (University of Haifa at Oranim, Israel), Saeqa D. Vrtilek (Harvard-Smithsonian Center for Astrophysics)
Abstract
Planetary nebulae, the ejected outer envelopes of
expired stars with initial masses
in the range 1-8
,
have long been
known to exhibit large departures from spherical
symmetry in optical images. With the recent discovery by
Chandra of extended X-ray emission from a handful of
planetaries, we can investigate for the first time how such
asymmetries manifest themselves at high energy. In
particular, Chandra images have revealed that the X-ray
emitting regions of the young planetary nebulae BD
and NGC 7027 are much more asymmetric than
the optical nebulosities. The rather low X-ray emission
temperatures of both objects (
K)
support the notion that heat conduction effects, and hence
magnetic fields, determine their X-ray emission
morphologies. The observed asymmetries also could be
generated by a combination of clumpy extinction and
collimated outflows, however. To evaluate these possibilities, we
are conducting a quantitative study of the optical, IR, and
X-ray morphologies of these objects.
CATEGORY: NORMAL STARS AND WHITE DWARFS