First Milky Way’s Galactic Bone Identified – ‘Nessie Bone’

An international team of astronomers led by Dr Alyssa Goodman of the Harvard-Smithsonian Center for Astrophysics has identified a bone-like filament in our Milky Way Galaxy.

The Nessie bone was discovered while studying a dust cloud that in 2010 was nicknamed after the Loch Ness Monster. Nessie turns out to be at least twice, and perhaps as much as eight times, longer than originally claimed. Both the original 2010 Nessie and the extended structure are outlined and labeled here on a Spitzer infrared image (NASA / JPL / SSC)

“This is the first time we’ve seen such a delicate piece of the galactic skeleton,” said Dr Goodman, who presented the discovery at a meeting of the American Astronomical Society in Long Beach, California.

Spiral galaxies display internal bones or endoskeletons. Observations have found long skinny features jutting between galaxies’ spiral arms. These relatively straight structures are much less massive than the curving spiral arms. 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.

The team spotted the galactic bone while studying a dust cloud nicknamed Nessie.

The central part of the Nessie bone was discovered in 2010 by Dr James Jackson of Boston University, who named it after the Loch Ness Monster.

Dr Goodman’s team noticed that Nessie appears at least twice, and possibly as much as eight times, longer than Jackson’s original claim.

Radio emissions from molecular gas show that the feature is not a chance projection of material on the sky, but instead a real feature. 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.

“This bone is much more like a fibula – the long skinny bone in your leg – than it is like the tibia, or big thick leg bone,” Dr Goodman said.

“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.”

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Bibliographic information: Goodman AA et al. The Bones of the Milky Way. 221st AAS Meeting. Long Beach, CA. January 8, 2013