This computer simulation shows the gravitational interaction of two young star clusters in a nearby star-forming region. The three and a half million years of the encounter have been compressed into just 27 seconds. The smaller star cluster approaches from the left, has its trajectory bent strongly as it swings by the larger cluster, and then returns for a second pass. The visualization then zooms in and dissolves to a Hubble Space Telescope image of a suspected pair of interacting star clusters in 30 Doradus (also known as the Tarantula Nebula) located 170,000 light-years away. After a partial zoom out, the simulation moves forward in time for another 1.4 million years to show the clusters merging into a single cluster.
At the start of the simulation, the smaller cluster is not gravitationally bound to the large cluster. After the first interaction, the cluster pair become gravitationally entwined and destined to merge together. A noticeable byproduct of the encounter is that interactions between stars efficiently eject massive stars from the smaller cluster. In addition, the stars in the smaller cluster are one million years older than those in the larger cluster. While all the stars shown are initially hot and blue, some reach the end of their lives during the simulation and evolve to cooler red giant stars.
Credit: NASA, ESA, M. Gieles (University of Cambridge, UK), and F. Summers