Our solar system sits between two major spiral arms of the home galaxy in a structure called the Local Arm that, although previously thought to be only a small spur, instead is much more like the adjacent major arms and is likely a significant branch of one of them, they said.
"Our new evidence suggests that the Local Arm should appear as a prominent feature of the Milky Way," Alberto Sanna of the Max-Planck Institute for Radio Astronomy said at the American Astronomical Society's meeting in Indianapolis.
Astronomers have long struggled to determine the structure of the Milky Way, an effort made difficult by the Earth's position within it, and while astronomers have long agreed the galaxy has a spiral structure, there are disagreements on how many arms it has and on their specific locations.
Researchers have used the ultra-sharp radio vision of the National Science Foundation's Very Long Baseline Array to make new measurements, a release from the National Radio Astronomy Observatory in Charlottesville, Va., reported Tuesday.
The measurements have led to an upgrade to the status of the Local Arm within which the solar system resides, between two major spiral arms of the galaxy, the Sagittarius Arm and the Perseus Arm.
"Based on both the distances and the space motions we measured, our Local Arm is not a spur," Sanna said. "It is a major structure, maybe a branch of the Perseus Arm, or possibly an independent arm segment."