According to a recent
press release,
"...observations from the Herschel
Space Observatory show a bizarre,
twisted ring of dense gas at the
center of our Milky Way galaxy." The
ring observation is not new, as
reported in a previous Picture of
the Day. What is new is the bizarre
figure-eight structure.
What Herschel saw was not visible
to optical telescopes, since the
intervening dust and gas obscures
the view of our galaxy's nucleus.
Several
past infrared views had
revealed a portion of the ring,
sparking speculations that it exists
because inertia from galactic spin,
as well as that imparted by gas
moving across the central bulge,
creates a standing wave.
The latest images show the
complete ring, with the
figure-eight or
"infinity" structure. The warped
nucleus of
galaxy Centaurus A was
discussed in a previous Picture of
the Day. It was noted that many
active galaxies display transverse,
donut-shaped plasma discharges, as
well as plasma jets erupting from
their axes. Twisted rings inside
galaxies form because helical
electric currents squeeze plasma
inside them, creating cosmic
“transmission lines” through space
known as Birkeland currents. These
currents confine clouds of ionized
gas within electromagnetic fields,
causing star formation and toroidal
currents around the galactic axis on
its equator.
In a recent Picture of the Day,
it was reported that the reason
galactic rings flatten and curl at
the edges is because of plasma
instabilities in the torus. As
electric current density increases:
"The edges curl in and out and
upwards and downwards to the current
flow.” [Anthony L. Peratt,
“Characteristics for the Occurrence
of a High-Current, Z-Pinch Aurora as
Recorded in Antiquity,” IEEE
Transactions on Plasma Science,
Volume 31, Number 6, December 2003,
pages 1195-6.]
An electric discharge in plasma
creates a tube-like magnetic sheath
along its axis. If enough current
flows through the circuit, the
discharge will cause the sheath to
glow, sometimes creating a number of
other sheaths within it. The sheath
is called a “double layer.”
Double layers form when positive
charges build up in one region of a
plasma cloud and negative charges
build up nearby. A powerful electric
field appears between the two
regions, which accelerates charged
particles. The electric charges
spiral in the magnetic fields,
emitting X-rays, extreme
ultraviolet, and sometimes gamma
rays.
Toroidal filaments couple to
hourglass-shaped current sheets that
are subject to diocotron
instabilities: the current flow
through plasma sometimes
forms vortices that
change into distorted curlicue
shapes. This phenomenon has been
witnessed in many laboratory
experiments, as well as in the polar
aurorae.
Stephen Smith
Hat tip to Larry White
New
DVD
The Lightning-Scarred
Planet Mars
A video documentary that could
change everything you thought you
knew about ancient times and
symbols. In this second episode of
Symbols of an Alien Sky, David
Talbott takes the viewer on an
odyssey across the surface of Mars.
Exploring feature after feature of
the planet, he finds that only
electric arcs could produce the
observed patterns. The high
resolution images reveal massive
channels and gouges, great mounds,
and crater chains, none finding an
explanation in traditional geology,
but all matching the scars from
electric discharge experiments in
the laboratory. (Approximately 85
minutes)
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