Scientists discover a piece of the Milky Way's galactic skeleton

Credit: NASA/JPL/SSC
Credit: NASA/JPL/SSC
A long tendril of dust and gas that stretches 300 light-yers long appears dark in this infrared image from the Spitzer Space Telescope. Researchers say the thin is a part of the structure of the spiral Milky Way -- one “bone” in the galaxy’s skeleton.

When James Jackson, an astronomer at Boston University, first noticed a dust cloud that curved across the sky in 2010, he saw something serpentine in its skinny shape and called it “Nessie,” after the Loch Ness monster.

Scientists began to wonder whether they were seeing the whole cloud, spurring further research.

Now, a team including Jackson has announced they were looking at just a portion of a twisting line of dust and gas that is longer than anyone expected. The dark, dense cloud of dust and gas is massive, spanning some 300 light-years. It is 80 times longer than it is wide. At the meeting of the American Astronomical Society in Long Beach, Calif., Alyssa Goodman, a professor of astronomy at the Harvard-Smithsonian Center for Astrophysics, announced on Tuesday that the expanse of dust and gas appears to be a structural component of the Milky Way, something she compares to a bone in the galaxy’s skeleton.

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The Milky Way is a spiral galaxy, with arms that swirl outward, and researchers believe the “bone” they found is one of the arms of the spiral. To be specific, it’s part of the Scutum-Centaurus arm. But there are many things they don’t know about what they’ve discovered, because although telescopes have taken many pictures of spiral galaxies, we’ve never been able to turn the same scrutiny on our own neighborhood.

“We’ve never seen a real picture of our galaxy, because we can’t get far enough outside our galaxy to take a picture of it. What we have are cartoon pictures of what our galaxy looks like,” Goodman said. “Now, if we know this bone is there, this would be the easiest one to find. If we know what we’re looking for, we can look through the rest of the galaxy, with more and more sensitive surveys of the whole galaxy and probably map out the whole skeleton.”

Such clouds of dust and gas play a key role in the life of a galaxy, according to Goodman, forming new stars.