A 4th-magnitude open cluster in Crux, near the Coalsack dark nebula, also known as NGC 4755 or the Kappa Crucis Cluster. Most of the bright stars in the cluster are blue-white in colour, including Kappa Crucis, a magnitude 5.9 supergiant, but an 8th-magnitude red supergiant lies near the centre. The cluster is just under 5000 l.y. away. It was named by J. F. W. Herschel who compared it to a collection of jewels. The name Jewel Box is sometimes also applied to M6 in Scorpius, better known as the Butterfly Cluster.
Subjects: Astronomy and Astrophysics.