Milky Way spiral arms may be 10% larger than previously estimated

Astronomers have discovered that the outer spiral arms of the Milky Way may extend 10% further than previously estimated. The findings are based on precise distance measurements to dust clouds within the galaxy's arms.

Researchers utilized X-ray data from NASA’s Chandra observatory and the European Space Agency’s (ESA) XMM-Newton to analyze X-ray echoes. These echoes were produced by violent cosmic phenomena outside the Milky Way, such as gamma-ray bursts (GRBs) resulting from neutron star mergers or massive star collapses. By studying the annular structure of these echoes, scientists calculated the distances of the Perseus, Outer, and Scutum-Centaurus arms relative to Earth.

The results indicate that both the Outer and Scutum-Centaurus arms are approximately 10% more distant from the galactic center than once thought. Unlike previous methods that relied on assumptions regarding galactic rotation, this geometric technique reduces uncertainty in the peripheral regions of the galaxy.