Deep Sky
M6
NGC6405

Butterfly Cluster
Constellation: Scorpius
Most of the members of the open cluster are hot blue B type stars,  however that bright one is a K type orange giant star.  This bad boy is known as BM Scorpii.  You'd think a fire breather like this one would have a little more colorful name than BM...  It is classified as a semiregular variable star, and its magnitude varies from +5.5 to +7.  Kind of wish we knew, how bright he was this September night.
Astronomers had different distances for the Butterfly, now they figure it is about 1,600 light-years from us.  It is some 12 light-years across (some big buttrfly).  Its overall brightness or magnitude is 4.2.
The first astronomer to record the butterfly was Giovanni Battista Hodiema in 1654.  The Messier dude put it in his catalogue as M6, in 1764.
m6
10 images
20 sec
date: 9-15-12