Assertion: nebula's star | /r/CapableOf | form cluster
Facets:
Source sentences:
text: In 1931, Robert J. Trumpler noted that the fainter stars near the Trapezium formed a cluster, and he was the first to name them the Trapezium cluster.
text: Swiss-American astronomer Robert Julius Trumpler was the first to use the name Trapezium Cluster for the young open cluster inside M42 after discovering that the fainter stars near the Trapezium asterism formed a cluster.