Astronomers Push 2 Milky Way Spiral Arms 10% Farther Using Gamma-Ray Burst Echoes
Updated
Updated · Science@NASA · Jul 1
Astronomers Push 2 Milky Way Spiral Arms 10% Farther Using Gamma-Ray Burst Echoes
3 articles · Updated · Science@NASA · Jul 1
Summary
Two outer Milky Way arms—the Outer and Outer Scutum-Centaurus—appear about 10% farther from the galactic center than earlier estimates, based on a study published Wednesday in Astronomy & Astrophysics.
Three gamma-ray bursts let researchers measure dust-cloud distances geometrically: X-ray light echoes formed rings whose sizes revealed how far the spiral-arm material lies from Earth, avoiding rotation-based assumptions that grow less reliable in the galaxy’s outskirts.
Chandra and ESA’s XMM-Newton supplied the data for three arms—Perseus, Outer and Outer Scutum-Centaurus—and the team estimated the most distant arm’s dust cloud spans about 3,500 light-years, suggesting the measurement reflects the arm’s full thickness.
The revision could force updates to estimates of the Milky Way’s mass and overall width, though the method may be hard to repeat because suitable gamma-ray bursts shining through the galactic plane have appeared only a handful of times in 25 years.