January 9, 2013
Astronomers Discover The First “Bone” In the Milky Way
redOrbit Staff & Wire Reports - Your Universe Online
Astronomers affiliated with the Harvard-Smithsonian Center for Astrophysics (CfA) have discovered a new structure in the Milky Way — a lengthy tendril comprised of dust and gas.
The tendril — or “bone” as they refer to it — is long and slender, drawing comparisons to the fibula, or calf bone. In a statement, lead author Alyssa Goodman stated that this marks the first time that scientists have been able to locate such a “delicate piece” of the Milky Way´s so-called galactic skeleton.
While we know that our galaxy is a spiral galaxy — or, as the CfA describes it, a “pinwheel-shaped collection of stars, gas and dust” with “a central bar and two major spiral arms that wrap around its disk” — it has proven difficult to determine its exact structure and appearance since we reside in it.
The team explained that similar features have been discovered in other spiral galaxies by analyzing them with infrared wavelengths of light. These longer, thinner arms are relatively straight and stick out from between the galaxies´ spiral arms. They also tend to be far less massive than their curved counterparts.
“Computer simulations of galaxy formation show webs of filaments within spiral disks. It is very likely that the newly discovered Milky Way feature is one of these "bone-like" filaments,” they said. Goodman presented her team´s findings Tuesday at a meeting of the American Astronomical Society (AAS) in California.
She and her associates first discovered the tendril or “bone” while they were studying a dust cloud called “Nessie” in honor of the Loch Ness Monster. The dust cloud was discovered in 2010 by James Jackson of Boston University with the aid of data from the Spitzer Space Telescope.
Goodman´s analysis, however, led them to realize that it was actually between two and eight times longer than Jackson had originally estimated.
“Radio emissions from molecular gas show that the feature is not a chance projection of material on the sky, but instead a real feature,” CfA researchers explained. “Not only is ℠Nessie´ in the galactic plane, but also it extends much longer than anyone anticipated. This slender bone of the Milky Way is more than 300 light-years long but only 1 or 2 light-years wide. It contains about 100,000 suns' worth of material, and now looks more like a cosmic snake.”
"It's possible that the 'Nessie' bone lies within a spiral arm, or that it is part of a web connecting bolder spiral features. Our hope is that we and other astronomers will find more of these features, and use them to map the skeleton of the Milky Way in 3-D," added Goodman.