Cosmic nebulae usually look like disorganized blobs in space, but astronomers using the Spitzer Space Telescope reported on March 15, 2006 that they have found a nebula twisted like the double helix on DNA. (Xinhua/Reuters)

LOS ANGELES, March 15 (Xinhuanet) -- With NASA's Spitzer Space Telescope, U.S. astronomers spotted an unprecedented DNA-like nebula near the center of our Milky Way.

    The observed part of elongated double helix nebula, stretching 80 light years in length, sits 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.

    The researchers published their findings in the March 16 edition of the journal Nature.

    "We see two intertwining strands wrapped around each other as in a DNA molecule," said Mark Morris, lead author of the study at the University of California, Los Angeles.

    "Nobody has ever seen anything like that before in the cosmic realm. Most nebula 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 fancy feature of the nebula could be driven by magnetic waves at the center of galaxy, Morris explained. Galactic center has a strong, highly-ordered magnetic field, and the magnetic field lines are oriented perpendicular to the plane of the galaxy.

    "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," he said. "You can regard these magnetic field lines as akin to a taut rubber band."

    "That's what is being sent down the magnetic field lines of our galaxy," Morris said. "We see this twisting torsional wave propagating out."

    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, according to the researchers.

    The magnetic field at our 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.

    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.

    But what launches the wave, twisting the magnetic field lines near the center of the Milky Way? The researchers hypothesized that the magnetic field lines are anchored in a massive gas disk orbiting 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. Enditem