New study details skeleton of the Milky Way galaxy

BOSTON, Dec. 21 (UPI) -- Researchers with the Harvard-Smithsonian Center for Astrophysics claim to have traced the "skeletal structure" of the Milky Way galaxy. They shared their findings earlier this month in the Astrophysical Journal.

Astronomers Catherine Zucker, Cara Battersby and Alyssa Goodman argue that the Milky Way's spiral arms are organized around distinct skeletal features. They describe these features, or bones, as long, thin, high-contrast filaments of cold, dark clouds of gas and dust. The filaments can stretch thousands of light-years in length, but boast a girth of only a few light-years.

Documenting these skeletal features may be key to understanding our home galaxy's broader structure.

Despite decades of studies and observations, researchers still aren't in agreement on whether the Milky Way has two or four spiral arms. The exact location and design of these arm aren't entirely clear either. Astronomers also aren't sure whether inter-arm structure are mostly web-like or feature distinctive spurs of stars and gas.

A map of the galaxy's bones may answer some of these questions, researchers say.

The first skeletal structure was spotted by astronomers during a mid-infrared survey of Milky Way's arms conducted five years.

The astronomers' latest infrared survey presents evidence of 10 new potential skeletal features, all positioned near the galaxy's mid-plane. Each of the ten have an aspect ratio -- or length-to-width ratio -- of at least 50-to-1. All weigh at least several thousand solar masses.

Researchers expect future surveys to reveal hundreds of similar bones.

"Ultimately, if we can reliably identify hundreds of Milky Way bones," researchers wrote, "it should be possible to combine the 'skeleton' suggested by bones with other tracers of galactic structure, in order to piece together a much better view of the Milky Way's structure than we have now."