Gas is needed for star formation. In clusters, clusters have long been considered unable to form new stars because large amounts of gas are dissipated in the early stages of cluster formation. Only collisions or coalescence between stars are possible to replenish burning material for older stars. Make them look younger than other stars. Stars formed by collision or merging are called blue discrete stars, and their names come from the evolution process that is quite different from that of most stars, which makes them dissociate from the evolution trajectory predicted by theory. Using the observed data, a research team studied the blue discrete stars in the young cluster NGC.2173 and observed an unusual group of blue discrete stars in this young cluster for the first time. It was found that the cluster contained blue discrete stars formed by sudden outbursts.
The main idea of this passage is that there are unusual blue discrete stars in the cluster.