X-ray images of Eta Carinae
(credit: NASA / Chandra project, 1999)
In this famous AXAF (Chandra) image of Eta Carinae, colors indicate
temperatures of the hot
X-ray-emitting gas. The gas is essentially thermal, probably heated
by shocks. The blue region
at the center is mostly above 40 million degrees K, indicating flow
speeds close to 3000 km/s
within 100 AU of the star -- the wind of a hot companion star, or
localized streams in the primary
wind? (The central region is probably unresolved at Chandra's resolution
even though it appears
somewhat extended in the picture.) The outer ejecta are much cooler, with flow
speeds below
1500 km/s.
In both regions, the X-ray luminosity and X-ray-emitting mass are tiny
compared to those
observed at ultraviolet-visual-infrared wavelengths. Integration times when
observing Eta Car
are agreeably short for almost everyone except the X-ray astronomers, who
need to integrate
for hours or even days to collect a decent number of photons!
Relative scale sizes can be judged from the next picture.
(Above:) Here we 've superimposed an HST/WFPC2 image of the Homunculus
onto the same
X-ray picture , to show how large the outer X-ray regions are. 20" corresponds
to a projected
linear distance of about 45000 AU or 0.7 lightyear.
A
Chandra/Harvard site has more X-ray images.
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