Butterfly Cluster

The Butterfly Cluster (also known as M6 or NGC 6405) is an open cluster in the Orion Arm of the Milky Way Galaxy.

Most of the bright stars in this cluster are hot, blue B type stars but the brightest cluster member is a K type orange giant star. This star, known as BM Scorpii, is classed as a semiregular variable star. This orange star contrasts sharply with its blue neighbours in the cluster.

The cluster has a spatial dimension of some 12 light years.