26,119 research outputs found
XMM-Newton Detection of Hot Gas in the Eskimo Nebula: Shocked Stellar Wind or Collimated Outflows?
The Eskimo Nebula (NGC 2392) is a double-shell planetary nebula (PN) known
for the exceptionally large expansion velocity of its inner shell, ~90 km/s,
and the existence of a fast bipolar outflow with a line-of-sight expansion
velocity approaching 200 km/s. We have obtained XMM-Newton observations of the
Eskimo and detected diffuse X-ray emission within its inner shell. The X-ray
spectra suggest thin plasma emission with a temperature of ~2x10^6 K and an
X-ray luminosity of L_X = (2.6+/-1.0)x10^31 (d/1150 pc)^2 ergs/s, where d is
the distance in parsecs. The diffuse X-ray emission shows noticeably different
spatial distributions between the 0.2-0.65 keV and 0.65-2.0 keV bands.
High-resolution X-ray images of the Eskimo are needed to determine whether its
diffuse X-ray emission originates from shocked fast wind or bipolar outflows.Comment: 4 pages, 2 figures, accepted in Astronomy and Astrophysics Letter
Bubbles and Superbubbles
An isolated massive star can blow a bubble, while a group of massive stars
can blow superbubbles. In this paper, we examine three intriguing questions
regarding bubbles and superbubbles: (1) why don't we see interstellar bubbles
around every O star? (2) how hot are the bubble interiors? and (3) what is
going on at the hot/cold gas interface in a bubble?Comment: 8 page, 5 figures, to appear in the proceedings of "How does the
Galaxy work? A Galactic Tertulia with Don Cox and Ron Reynolds", eds Alfaro,
Perez & Franc
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