Astronomers have made an exciting discovery: 55 fast-moving stars that were thrown out of a young star cluster called R136.
This star cluster is located in the Large Magellanic Cloud, a small galaxy near our Milky Way.
Using data from the European Gaia Space Telescope, the astronomers increased the number of known “runaway stars” in this area by ten times.
Their findings were published in Nature by a team that includes Simon Portegies Zwart from Leiden Observatory.
When a star cluster like R136 forms, the stars are packed tightly together, and their movements can sometimes cause near-collisions. These close encounters can launch some stars out of the cluster at high speeds.
The team, led by Ph.D. student Mitchel Stoop, discovered that about a third of R136’s most massive stars have been ejected in the last few million years.
These stars are speeding away at more than 100,000 kilometers per hour and may travel up to 1,000 light years from their birthplace before eventually exploding as supernovas, leaving behind either a neutron star or a black hole.
Stoop and his team found two different times when these stars were ejected. The first event happened 1.8 million years ago when the cluster was just forming.
This fits with the idea that young clusters can eject stars during their formation. However, a second ejection event occurred more recently, just 200,000 years ago.
The stars from this second event are moving more slowly and in a specific direction, unlike the first batch that was shot off in random directions. The astronomers believe that this second ejection could be due to R136 interacting with another nearby star cluster, which was only discovered in 2012.
This suggests that the two clusters may merge in the future.
Massive stars are known for their short but brilliant lives. They shine extremely brightly—up to a million times brighter than the Sun—and mostly emit ultraviolet light, which ionizes hydrogen gas around them.
They usually explode as supernovas in the same region where they were born, surrounded by clouds of gas and dust that dampen their effects. However, the discovery that many massive stars are ejected early from their birth regions means their impact on galaxies might be even greater than previously thought.
These runaway stars may have played a significant role in the early universe by helping to re-ionize it with their ultraviolet light.
The Gaia Space Telescope, which provided the data for this study, is located 1.5 million kilometers from Earth. It measures the positions, distances, and speeds of more than a billion stars, making discoveries like this one possible.
This research shows that R136, with hundreds of thousands of stars, is a very special star cluster and helps us better understand the movement and impact of massive stars.
