Gazing deep into the cosmos, the James Webb Space Telescope (JWST) has unveiled a breathtaking view of Westerlund 1, a super star cluster located a staggering 12,000 light-years away in the constellation Ara. This celestial marvel, visible from Earth’s Southern Hemisphere, is the largest known star cluster in our Milky Way galaxy, making it the ultimate example of a “super star cluster.”
While most star clusters are about 10,000 times the mass of our sun, Westerlund 1 is a colossal behemoth, boasting a mass 50,000 to 100,000 times greater than our sun. This cluster harbors hundreds of incredibly massive stars, some reaching sizes 2,000 times larger than our own sun. Imagine their sheer scale – if they were in our solar system, they would extend outwards to the orbit of Saturn!
The brilliance of these stars is equally astonishing. They shine with a luminosity 1 million times brighter than our sun. If Earth were orbiting a star within Westerlund 1, our night sky would be a dazzling spectacle of hundreds of stars as bright as the full moon.
This latest Picture of the Month from the JWST reveals a cosmic tapestry woven with the threads of stellar creation and destruction. The image showcases the cluster’s immense scale and the intricate details of its star-forming regions. Twists of red gas, visible at the top and center of the image, are a testament to the dynamic processes shaping this stellar nursery.
The image, captured by JWST’s Near Infrared Camera (NIRCam), unveils a hidden universe. Unlike optical telescopes like Hubble, which are obscured by interstellar clouds of gas and dust, the JWST can peer through this cosmic veil, its infrared vision penetrating the dust and gas to reveal the secrets hidden within.
The bright stars in the image are adorned with six large and two small snowflake-like diffraction spikes, a signature pattern created by the way light diffracts from the 18 hexagonal mirrors in the telescope’s primary mirror. The two horizontal lines through each star are a result of the light’s reflection from the primary mirror to a secondary mirror, held in place by two struts.
Westerlund 1 offers astronomers a glimpse into the Milky Way’s past, a time when our galaxy produced a far greater number of stars. This cluster, one of the few survivors from that era, provides valuable clues to understanding the Milky Way’s evolution, the lives and deaths of massive stars, and the processes that shaped our galaxy billions of years ago. As astronomers delve deeper into the secrets of Westerlund 1, they gain a greater understanding of the cosmic forces that shaped the universe we inhabit.