A new image of vast filaments of frigid interstellar dust
that reach across our Milky Way galaxy is giving scientists new clues into the
forces behind the birth of new stars and the galaxy's shape.
The European Space Agencys (ESA) Planck space observatory
took the new cosmic snapshot of dust structures spread across a region of space
within 500 light-years of the sun. In the image, the dust filaments link up to
the plane of Milky Way galaxy, which appears as a pink, horizontal bar across
the bottom of the image.
"What makes these structures have these particular
shapes is not well understood," said ESA's Planck project scientist Jan
Tauber in a statement.
The new image is color-coded to depict the temperatures
of different regions within the view. The whitish-pink areas are regions that
are just a few tens of degrees above absolute zero, the theoretical coldest
temperature possible in the universe (minus 459 degrees Fahrenheit or minus 273
degrees Celsius). Deeper, richer colors mark areas of minus 437 degrees
Fahrenheit (minus 261 degrees Celsius). That's just 12 degrees Celsius warmer
than absolute zero.
While the warmer dust is concentrated along the plane of
the Milky Way, the colder dust hovers above and below the galaxy's plane.
The Planck
observatory is designed to study the early universe by
studying the cosmic microwave background — light emitted just after the Big
Bang, which is thought to have created the universe 13.7 billion years ago.
The structures observed by Planck in the new image
include molecular clouds in more diffuse regions, as well as so-called "cirrus"
dust clouds. They are made of both dust and gas, though the interstellar gas
component is not directly visible, ESA officials said.
The clouds are pulled to and fro by a galaxy's rotation
and gravity, and can also be affected by radiation and particle jets that swirl
their component gas and dust around.
The bright clumps seen in the Planck image are collections
of matter that may offer a safe harbor for new star formation. As these clumps
collapse inward on themselves they become denser, offering a more substantial
shield against exterior light and radiation.
That shield can allow the clumps to cool and collapse
faster to make new stars, ESA officials said.
Planck launched in May 2009 alongside ESA's Herschel
infrared space observatory, which is also mapping
the universe to make detailed observation of structures
on a smaller scale than Planck's view.
The new image from Planck reinforces a cosmic oddity that
is perplexing astronomers, ESA officials said. That question is why the
large-scale dust filaments seen by Planck are similar to smaller-scale ones
observed by Herschel.
"That's a big question," Tauber said.
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