Milky Way map with highest resolution unveiled

After a 15-year study, an international team of astronomers has unveiled a map with the highest resolution to date of the spiral structure of the Milky Way, offering clear proof that it is a barred spiral galaxy with four major spiral arms.

The findings were presented in an article, “A New Map of the Milky Way,” published in the latest issue of the journal Scientific American as a cover story.

The piece is co-written by Mark Reid, from the Harvard-Smithsonian Center for Astrophysics, and Zheng Xingwu, from the Nanjing University School of Astronomy and Space Science. The article summarizes the results from the 15-year study completed by the two scientists, together with a team, led by German scientist Karl Menten.

The astronomers behind the new findings used Very Long Baseline Interferometry, an astronomical observing technique, to measure nearly 200 massive star-forming regions on the disk of the Milky Way.

They obtained the structure of the spiral arms of the galaxy, the location of the solar system, and the rotation speed of the solar system orbiting the Milky Way’s center.

They also charted the structure of the galaxy with a scale of approximately 100,000 square light years, Zheng said.

“This is the most accurate structural map of the Milky Way to date,” Zheng said. “It resolved a long-standing debate over whether the spiral comprises of four or two arms.”

The solar system is not located on the four prominent major arms but a tiny spur, or a Local Arm in the galaxy, the study stated.

Since the beginning of the 21st century, a group of 22 astronomers from eight countries including China, the United States, Germany and Italy, have launched a plan called the Bar and Spiral Structure Legacy Survey, known as the “BeSSeL Plan,” to clarify the structure of the Milky Way.