The James Webb Space Telescope (JWST) has given astronomers the clearest view of Westerlund 1, the largest young star cluster in the Milky Way. Previously obscured by interstellar gas and dust, this colossal stellar nursery has now been captured in remarkable detail, showcasing an extraordinary cluster of stars. Located about 12,000 light-years away in the constellation Ara, Westerlund 1 is known for its immense size and the sheer number of massive stars it contains. Some stars here are 2,000 times larger than the Sun, and if they were within our solar system, they would extend to Saturn’s orbit.
A Cluster Like No Other
Westerlund 1 is not an ordinary star cluster; it is a ‘super star cluster,’ far surpassing the mass of most clusters in the Milky Way. With a mass between 50,000 to 100,000 times that of the Sun, it dwarfs most other clusters, which typically weigh in at about 10,000 solar masses. Many stars in Westerlund 1 are shining a million times brighter than the Sun, making it a true galactic giant. If Earth orbited a star in Westerlund 1, the night sky would be illuminated by hundreds of stars as bright as the full moon.
Future Supernovae and JWST’s Unique Capabilities
Astronomers predict that more than 1,500 supernovae will light up Westerlund 1 in the next 40 million years. Currently, the cluster is only 3.5 to 5 million years old. The JWST was able to capture this hidden wonder because its Near Infrared Camera (NIRCam) can see through the gas and dust that blocks optical telescopes like Hubble. This ability allows scientists to study these massive stars and gain insights into the Milky Way’s history.