Unexpected Excess of Giant Planets in Star Cluster Messier 67
Astronomers have found that there are far more planets of the hot Jupiter type than expected in a cluster of stars called Messier 67. This surprising result was obtained using a number of telescopes and instruments. The denser environment in a cluster will cause more frequent interactions between planets and nearby stars, which may explain the excess of hot Jupiters. Ref. Source 3g.