UCLA scientists have stumbled upon a never-before-seen
phenomenon: a double-helix-shaped nebula reminiscent of the
structure of a DNA molecule, the genetic material of living
organisms.
The research is published in the March 16 edition of the journal
Nature.
“Most nebulae are formless, amorphous conglomerations of
dust and gas, but here 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 of the
article.
“This is the first time we have seen this high degree of
order, but we are considering it to be a more general
phenomenon,” he said.
The double-helix nebula is approximately 300 light-years from
the enormous black hole at the center of the Milky Way, and the
part of the nebula the astronomers observed stretches 80
light-years in length.
With the discovery of this nebula, scientists are now searching
outside the galaxy for other helix-shaped nebulae.
“We are currently working on a possible detection of an
even larger double helix in a close-by starburst galaxy,”
said Tuan Do, the article’s co-author and a UCLA astronomy
graduate student.
Do decoded the data from the Spitzer Space Telescope and created
the images of the first helix.
According to a UCLA press release, the Spitzer Space Telescope
is an infrared telescope managed by NASA’s Jet Propulsion
Laboratory in Pasadena, and its sensitivity and spatial resolution
were required to see the double-helix nebula clearly.
Just as one can visualize magnetic fields by sprinkling iron
filaments onto a surface with nearby magnets, nebulae containing
interstellar dust and gas can outline the traces of magnetic
fields, Morris said.
Astronomers refer to these thread-like cosmic structures as
filaments.
“Other filaments are visible in the traces of magnetic
fields created when the galactic center was formed, but these have
less coherent structure,” Do said.
“There must be a driver of the double-helix filaments
because we wouldn’t expect them to stay defined for so
long.”
Morris and his colleagues said the estimated 100,000-year-old
helix filaments may be caused by a huge disk of gas, known as the
circumnuclear disk, which orbits just a few light-years outside the
black hole at the center of the galaxy.
They hypothesize that magnetic lines are anchored in this disk,
and as the disk rotates around the black hole, the lines twist
around each other and produce a magnetic wave that extends away
from the base.
A fast-moving magnetic wave can carry small dust particles up
from the disk and trap them, providing something that can absorb
and emit infrared radiation, which is detected by the Spitzer
telescope, Morris said.
Former UCLA graduate student Keven Uchida is another co-author
on the Nature paper.