Butterfly Cluster (M6, NGC 6405)

Butterfly Cluster (M6, NGC 6405)

The Butterfly Cluster. Credit: AURA, NOAO, NSF.

The Butterfly Cluster (M6, NGC 6405) is an open cluster in the constellation Scorpius, 4° northwest of M7 (Ptolemy's Cluter), that contains about 80 stars roughly in the shape of a butterfly. Visible to the naked eye, it was first noted by Giovanni Hodierna before 1654. Its most conspicuous star is an orange giant K star of magnitude 6.2.


visual magnitude 5.3
angular size 25'
diameter 20 light-years
age about 50 million years
distance 2,000 light-years
position RA 17h 40.1m, Dec -32° 13'