A moth-like
structure with a 22-billion-mile wingspan is hovering out in space.
This giant
is actually a massive cloud of dust surrounding a nearby, young star imaged by
the Hubble Space Telescope that has shown astronomers that these dust
disks can take on unexpectedly unusual shapes.
Such disks are
typically flat, pancake-shaped structures where planets
can form. But HD 61005's disk breaks from the norm with a shape dubbed
"The Moth". The shape is produced by starlight scattering off the
dust.
"It is
completely unexpected to find a dust disk with this unusual shape," said
senior research scientist Dean Hines of the Space Science Institute in Corrales, New Mexico. "We think HD 61005 is plowing through a local patch of
higher-density gas in the interstellar medium, causing material within HD
61005's disk to be swept behind the star."
Hines said
that such a collision was unexpected "because the area through which our
Sun is moving was evacuated within the past few million years by at least one
supernova... Yet, here's evidence of dense material that's very close, only 100
light-years away."
The Moth is
part of a survey of sun-like stars that Hines and his colleagues have
undertaken with Hubble and NASA's Spitzer
Space Telescope to study the formation and evolution of planetary systems.
Astronomers
have found evidence that the environment a star forms in can influence the
prospects for planet formation around it. But Hines and his team are uncertain
how passage through a cloud similar to the one HD 61005 is in would affect
planet formation.
"What
effect this might have on the disk, and any planets forming within it, is
unknown," Hines said.
Hines and
his colleagues presented their finding today at a meeting of the American
Astronomical Society in Austin, Texas.
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