M6 and SH2-12

The magnificent M6 Butterfly Cluster is seen here, reminiscent of a Minbari White Star entering a Jumpgate near Babylon Five.

This beautiful cluster is situated near its neighbour, Sh2-12, which features strong emission lines of H-alpha (HA), Oxygen III (O3), and Sulfur II (S2). However, Sh2-12 is usually imaged in broadband only, making these emission lines a rare sight in most amateur astrophotography.

As of January 2022, the Butterfly Cluster is one of the few remaining objects within the Messier Catalog that the Hubble Space Telescope has not photographed.
Taken from my light-polluted Bortle 6 backyard in Melbourne, Australia (Pop 5 million night light-loving sports fans!)

About this Nebula

Top left of the frame is NGC 6383, an open cluster of stars in the constellation of Scorpius. It was discovered by English astronomer John Herschel in 1847. This is a large cluster of scattered stars that spans an angular diameter of 20′. The cluster NGC 6383 is located approximately 3,540 light-years (1,086 pc) from the Sun. It forms part of the Milky Way galaxy’s Carina–Sagittarius Arm in a star-forming region identified as Sh 2-012 and lies in front of a dust absorption cloud.

The Butterfly Cluster (catalogued as Messier 6 or M6 and as NGC 6405) is an open cluster of stars in the southern constellation of Scorpius. Its name derives from the vague resemblance of its shape to a butterfly.

Giovanni Battista Hodierna, who recorded the Butterfly Cluster’s existence in 1654, was the first astronomer to do so. However, Robert Burnham Jr. proposed that the 2nd-century astronomer Ptolemy may have seen it with the naked eye while observing its neighbour, the Ptolemy Cluster (M7).
Credit for the discovery is usually given to Jean-Philippe Loys de Chéseaux in 1746. Charles Messier observed the cluster on May 23, 1764, and added it to his Messier Catalog.

Estimates of the Butterfly Cluster’s distance have varied over the years. Wu et al. (2009) found a distance estimate of 1,590 light-years, giving it a spatial dimension of some 12 light-years. Modern measurements show its total visual brightness to be a magnitude of 4.2. The cluster is estimated to be 94.2 million years old.
Most of the bright stars in this cluster are hot, blue B-type stars, but the brightest member is a K-type orange giant star, BM Scorpii, which contrasts sharply with its blue neighbours in photographs.