Westerlund 1 is a super star cluster, a massive grouping of gravitationally-bound stars producing stellar newborns at a prodigious rate.
Astronomers used the Chandra X-ray Observatory and existing optical data from the Hubble Space Telescope to capture a new image of Westerlund 1.
It’s thought super star clusters like Westerdlund 1 were the main source of rapid star formation in the Milky Way’s early history.
So learning more about them could reveal more about how our Galaxy evolved.
Westerlund 1 and star formation in the Milky Way
Currently only a few stars form in the Milky Way every year.
But about 10 billion years ago, astronomers think the Galaxy was churning out hundreds of stars a year.
This was the Milky Way’s peak star-forming era, and the rate of star formation has been declining ever since.
Most of this rapid star formation likely occurred in massive clusters of stars – known as ‘super star clusters’, like Westerlund 1.
About Westerlund 1
Westerlund 1 is about 3-5 million years old and is the biggest of the remaining super star clusters in the Milky Way.
It’s thought to contain the same amount of mass as 50,000 – 100,000 Suns.
Westerlund 1 just 13,000 lightyears from Earth, making it the closest super star cluster to our Solar System.
Studying the image
This new image was produced using 12 days of observations with the Chandra X-ray Observatory, along with previously released data from the Hubble Space Telescope.
X-rays detected by Chandra in white and pink show young stars and diffuse, heated gas throughout the cluster.
This gas appears in pink, green and blue, in order of increasing temperature.
The stars captured by Hubble appear as yellow and blue dots.
Chandra’s dataset of Westerlund 1 has more than tripled the number of X-ray sources known in the cluster.
It’s the first data publicly released from the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) by astronomers from the Italian National Institute of Astrophysics in Palermo.
It found that 1,075 stars detected by Chandra are squished into the core of Westerlund 1, just 4 lightyears from the centre.
This is the same distance as between the Sun and Proxima Centauri, the closest star to our Sun, which shows just how crowded the centre of Westerlund 1 is.
And the diffuse emission picked up by Chandra amounts to the first time a halo of hot gas has been detected around the centre of the star cluster.
This is enabling astronomers to get a better idea of Westerlund 1’s formation, evolution and current mass.
Find out more about the study by reading the official paper, published in the journal Astronomy and Astrophysics.