Astronomers Report Unprecedented Double Helix Nebula Near Center of the Milky Way (Forwarded)

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FOR IMMEDIATE RELEASE: Wednesday, March 15, 2006

Astronomers Report Unprecedented Double Helix Nebula Near Center of the
Milky Way

Astronomers report an unprecedented elongated double helix nebula near the
center of our Milky Way galaxy, using observations from NASA's Spitzer
Space Telescope. The part of the nebula the astronomers observed stretches
80 light years in length. The research is published March 16 in the
journal Nature.

"We see two intertwining strands wrapped around each other as in a DNA
molecule," said Mark Morris, a UCLA professor of physics and astronomy,
and lead author. "Nobody has ever seen anything like that before in the
cosmic realm. Most nebulae are either spiral galaxies full of stars or
formless amorphous conglomerations of dust and gas -- space weather. What
we see indicates a high degree of order."

The double helix nebula is approximately 300 light years from the enormous
black hole at the center of the Milky Way. (The Earth is more than 25,000
light years from the black hole at the galactic center.)

The Spitzer Space Telescope, an infrared telescope, is imaging the sky at
unprecedented sensitivity and resolution; Spitzer's sensitivity and
spatial resolution were required to see the double helix nebula clearly.

"We know the galactic center has a strong magnetic field that is highly
ordered and that the magnetic field lines are oriented perpendicular to
the plane of the galaxy," Morris said. "If you take these magnetic field
lines and twist them at their base, that sends what is called a torsional
wave up the magnetic field lines.

"You can regard these magnetic field lines as akin to a taut rubber band,"
Morris added. "If you twist one end, the twist will travel up the rubber
band."

Offering another analogy, he said the wave is like what you see if you
take a long loose rope attached at its far end, throw a loop, and watch
the loop travel down the rope.

"That's what is being sent down the magnetic field lines of our galaxy,"
Morris said. "We see this twisting torsional wave propagating out. We
don't see it move because it takes 100,000 years to move from where we
think it was launched to where we now see it, but it's moving fast --
about 1,000 kilometers per second -- because the magnetic field is so
strong at the galactic center -- about 1,000 times stronger than where we
are in the galaxy's suburbs."

A strong, large-scale magnetic field can affect the galactic orbits of
molecular clouds by exerting a drag on them. It can inhibit star
formation, and can guide a wind of cosmic rays away from the central
region; understanding this strong magnetic field is important for
understanding quasars and violent phenomena in a galactic nucleus. Morris
will continue to probe the magnetic field at the galactic center in future
research.

This magnetic field is strong enough to cause activity that does not occur
elsewhere in the galaxy; the magnetic energy near the galactic center is
capable of altering the activity of our galactic nucleus and by analogy
the nuclei of many galaxies, including quasars, which are among the most
luminous objects in the universe. All galaxies that have a
well-concentrated galactic center may also have a strong magnetic field at
their center, Morris said, but so far, ours is the only galaxy where the
view is good enough to study it.

Morris has argued for many years that the magnetic field at the galactic
center is extremely strong; the research published in Nature strongly
supports that view.

The magnetic field at the galactic center, though 1,000 times weaker than
the magnetic field on the sun, occupies such a large volume that it has
vastly more energy than the magnetic field on the sun. It has the energy
equivalent of 1,000 supernovae.

What launches the wave, twisting the magnetic field lines near the center
of the Milky Way? Morris thinks the answer is not the monstrous black hole
at the galactic center, at least not directly.

Orbiting the black hole like the rings of Saturn, several light years
away, is a massive disk of gas called the circumnuclear disk; Morris
hypothesizes that the magnetic field lines are anchored in this disk. The
disk orbits the black hole approximately once every 10,000 years.

"Once every 10,000 years is exactly what we need to explain the twisting
of the magnetic field lines that we see in the double helix nebula,"
Morris said.

Co-authors on the Nature paper are Keven Uchida, a former UCLA graduate
student and former member of Cornell University's Center for Radiophysics
and Space Research; and Tuan Do, a UCLA astronomy graduate student. Morris
and his UCLA colleagues study the galactic center at all wavelengths.

NASA's Jet Propulsion Laboratory in Pasadena, Calif., manages the Spitzer
Space Telescope mission for the agency's Science Mission Directorate.
Science operations are conducted at the Spitzer Science Center at the
California Institute of Technology. JPL is a division of Caltech. NASA
funded the research.

IMAGE CAPTION:
[http://www.newsroom.ucla.edu/downloads.asp?RelNum=6903]
The double helix nebula. (The image uses false colors because the eye is
not sensitive to infrared light.) The spots are infrared-luminous stars,
mostly red giants and red supergiants. Many other stars are present in
this region, but are too dim to appear even in this sensitive infrared
image.

Credit: NASA/JPL-Caltech/UCLA


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