January 8th, 2013 by James Ayre
For the first time one of the ‘bones’ of the Milky Way have been identified by researchers. ‘Bones’ and endoskeletons are often visible in spiral galaxies, but as we are within the Milky Way it is more difficult to see what is what, as compared to our more clear observations of other galaxies.
The newly identified ‘bone’ structure is essentially “a long tendril of dust and gas” densely packed within the larger spiral arms of the galaxy.
“This is the first time we’ve seen such a delicate piece of the galactic skeleton,” says primary author Alyssa Goodman of the Harvard-Smithsonian Center for Astrophysics.
“Other spiral galaxies also display internal bones or endoskeletons. Observations, especially at infrared wavelengths of light, 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 galactic bone was spotted by the researchers while investigating a dust cloud called ‘Nessie’. “The central part of the ‘Nessie’ bone was discovered in Spitzer Space Telescope data in 2010 by James Jackson (Boston University), who named it after the Loch Ness Monster. 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,” explains Goodman.
“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,” she adds.
Discoveries like this show how much remains unknown about the galaxies of the Universe, including the Milky Way within which we live. The modern scientific investigation of the stars and other phenomena observed in space is a very recent undertaking. And this scientific knowledge remains very limited by the short time-span of its observations and conclusions. Future discoveries could very well be completely outside of the currently accepted paradigms.
Image Credits: NASA/JPL/SSC
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