"Just three years ago
the Hubble Space Telescope provided a dazzling image of a star that
was blowing off massive quantities of material in a blast that
looked like a supernova yet, mysteriously, wasn't one.
Now the
Chandra X-ray Observatory has looked at
Eta Carina and showed
details that are, well, shocking."
A Hubble Space Telescope
image of Eta Carina is shown scaled to fit within the much larger
X-ray nebula discovered by
Chandra.
The lobes are as wide as our solar system and expanding in opposite
directions away from a central bright disk at speeds in excess of 1
million km/h (600,000 mph).
The odd shape is believed to be partly due
to the star's intense magnetic field channeling plasma.
"It is not what I expected,"
said Dr. Fred Seward of the Harvard-Smithsonian Center for
Astrophysics.
The new X-ray observation shows three distinct
structures: an outer, horseshoe-shaped ring about 2 light years in
diameter, a hot inner core about 3 light-months in diameter, and a hot
central source less than 1 light-month in diameter which may contain the
superstar that drives the whole show.
The outer ring provides evidence
of another large explosion that occurred over 1,000 years ago.
All three structures are thought to represent shock waves produced by
matter rushing away from the superstar at supersonic
speeds.
The temperature of the shock-heated gas ranges from 60 million deg
Kelvin in the central regions to 3 million K (108 million deg. F to 5.4
million deg. F) on the outer structure.
Since it looked like a
supernova, one naturally would assume that was the end of the
star.
All that should be left are beautiful nebula and, perhaps, a
neutron star or black hole where the original star once
stood. Instead, Eta Carinae is still there (in a subtle bit
of grammar, astronomers refer to the star as Eta Carinae and the nebula
as Eta Carina).
As long ago as 1968 Dr Charles Bruce of the UK Electrical
Research Association identified planetary nebulae as bipolar
electrical discharges from a central star. Eta Carina obviously belongs
in that category.
Unfortunately, astronomers have very limited options in their toolkit to
explain 3 million degree temperatures and x-rays from gas more than a
light-year from the central star. However, it is simple to explain if it
is a plasma heated by electric current being fed into Eta Carinae.
Just as with our own sun, the highest "temperatures" are then
encountered outside the star. That would explain why there is relatively
little radiation from the star at the centre. Most of the power focused
on the hapless star is being intercepted by distant gas and dust and
radiated energetically into space.
Dr. Fred Seward said:
"I expected to see a
strong point source with a little diffuse emission cloud around it.
Instead we see just the opposite- a bright cloud of diffuse
emission, and much less radiation from the centre."
A star is merely a
focus of a galactic electric discharge and does not have to
provide internal energy to power objects like the Eta Carina nebula.
A good sense of the desperate ideas required to save the old model
can be gauged from the following post-script to the NASA report:
"As if its huffing and
puffing behavior weren't weird enough, Eta Carina also
appears to be a Death Star powerful enough to make Darth Vader turn
in his light saber.
Sveneric Johansson, a specialist in
atomic spectroscopy at the University of Lund in Sweden, has
proposed that Eta Carinae also is acting as a massive ultraviolet
laser.
Johansson, using Hubble observations made with the
Goddard High-Resolubon Spectrograph, reported in 1996 that his
interpretation is not yet proven, but that it appears to be the most
plausible explanation of the data."
Chandra.
speeds.
The temperature of the shock-heated gas ranges from 60 million deg
Kelvin in the central regions to 3 million K (108 million deg. F to 5.4
million deg. F) on the outer structure.