My off the wall guess is that
this is a rare star that has yet to orbit through a star cluster which would
strip these arms away. Otherwise, just
as a galaxy seems to form spiral arms It is plausible a dust halo will also
form a spiral structure.
What I would like to see is a
shock wave front lit up in this manner.
Maybe the star is traveling toward us?
The more I consider the options; most likely it is traveling toward us
or away from us. The symmetry is too nice.
It is always fun when the
universe dares you to explain it all.
A Star with Spiral Arms
Oct 31, 2011: For more than four hundred years, astronomers have
used telescopes to study the great variety of stars in our galaxy. Millions of
distant suns have been catalogued. There are dwarf stars, giant stars, dead
stars, exploding stars, binary stars; by now, you might suppose that every kind
of star in the Milky Way had been seen.
That's why a recent discovery is so surprising. Researchers using
the Subaru telescope in Hawaii
Two spiral arms emerge from the gas-rich disk around SAO 206462, a
young star in the constellation Lupus. This image, acquired by the Subaru
Telescope and its HiCIAO instrument, is the first to show spiral arms in a
circumstellar disk. The disk itself is some 14 billion miles across, or about
twice the size of Pluto's orbit in our own solar system. (Credit: NAOJ/Subaru)
[larger
image]
The name of the star is SAO 206462. It's a young star more than
four hundred light years from Earth in the constellation Lupus, the wolf.
SAO 206462 attracted attention because it has a circumstellar disk--that is, a
broad disk of dust and gas surrounding the star. Researchers strongly suspected
that new planets might be coalescing inside the disk, which is about twice as
wide as the orbit of Pluto.
When they took a closer look at SAO 206462 they found not planets, but
arms. Astronomers have seen spiral arms before: they’re commonly found in
pinwheel galaxies where hundreds of millions of stars spiral together around a
common core. Finding a clear case of spiral arms around an individual star,
however, is unprecedented1.
The arms might be a sign that planets are forming within the disk.
"Detailed computer simulations have shown us that the
gravitational pull of a planet inside a circumstellar disk can perturb gas and
dust, creating spiral arms,” says Carol Grady, an astronomer with Eureka
Scientific, Inc., who is based at NASA's Goddard Space Flight Center. “Now, for
the first time, we're seeing these dynamical features."
Grady revealed the image to colleagues on Oct. 19th at a meeting
at Goddard entitled Signposts of Planets.
Theoretical models show that a single embedded planet may produce a
spiral arm on each side of a disk. The structures around SAO 206462, however,
do not form a matched pair, suggesting the presence of two unseen worlds, one
for each arm.
Grady's research is part of a five-year international study of newborn
stars and planets using the giant 8.2 meter Subaru Telescope. Operated by the
National Astronomical Observatory of Japan ,
Subaru scans the heavens from a perch almost 14,000 feet above sea level at the
summit of the Hawaiian volcano Mauna Kea . From
there it has a crystal-clear view of innumerable young stars and their
planet-forming disks throughout the Milky Way.
"What we're finding is that once these systems reach ages of a few
million years—that’s young for a star--their disks begin to show all kinds of
interesting shapes,” says John Wisniewski, a collaborator at the University of Washington
in Seattle
However, it is not an open and shut case. The research team cautions
that processes unrelated to planets might give rise to these structures. Until
more evidence is collected--or until the planets themselves are detected--they
can’t be certain.
Whatever the cause of the arms, their reality is undeniable and the
great catalogue of stars has one more type. Stay tuned to science@nasa
for future entries.
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