A recent discovery by astronomers using the Gaia satellite has revealed that 55 high-speed stars have been ejected from the R136 star cluster, located in the Tarantula Nebula of the Large Magellanic Cloud (LMC). This finding indicates that up to one-third of the stars in R136 have been expelled over the last century.
The R136 cluster, approximately 160,000 light years from Earth, is one of the most massive known, containing some of the largest stars ever observed. These stars, formed from the surrounding gas in the nebula, are relatively young, at just a few million years old.
The ejection of stars from such clusters is a common phenomenon, driven by the random movements of gas and the gravitational interactions among stars. The team, led by University of Amsterdam PhD student Mitchel Stoop, recorded the ejected stars traveling at velocities exceeding 100,000 km/hr.
Analysis showed that the ejections occurred at different intervals in the cluster's history. The first event took place approximately 1.8 million years ago, coinciding with the cluster's formation, while a second event occurred around 200,000 years ago. Notably, the stars from the first ejection moved in random directions, whereas those from the second event exhibited a more uniform trajectory.
Co-author Alex de Koter suggested that the second ejection event may have resulted from interactions between R136 and a nearby cluster discovered in 2012, hinting at a potential future merger of the two clusters.
This discovery underscores the significant role of ejected stars in influencing other regions of the galaxy. Historically, such ejections may have contributed to the reionization of the universe, transitioning it from a state filled with ionized gas to one dominated by neutral hydrogen atoms.