The Constant Gardener - Messier 6 (M6), the Butterfly Cluster, with Sh2-12 & 13

Somewhere in the Scorpius constellation, a kaleidoscope of butterflies hovers behind a diligent horticulturist as he stoops to tend his crop.

Messier 6 (M6) – The Butterfly Cluster

The tight group of stars on the left is M6, the Butterfly Cluster—an open start cluster about 1,500 light years away that spans roughly 12 light years. It ostensibly contains around 80 stars, but that is an older measurement. Astronomers estimate its age at 92 to 100 million years old, which makes it a very young open star cluster.

Open star clusters (or “open clusters”) are collections of stars—perhaps a few dozen to a few thousand—that likely formed in the same molecular cloud but are not gravitationally bound to each other. They eventually wander away from each other and find their own paths through the galaxy. Our own sun was probably once part of an open cluster at one time but has since moved out on its own.

From our vantage, M6 is very close to the emission nebulas Sh2-12 and Sh2-13—the latter two responsible for me conjuring the image of an old man bent over his crop of vegetables.

Sh2-12

Sh2-12 is an emission nebula roughly 5,600 light years from Earth. The open star cluster NGC 6383 is close enough that it is thought to be the ionizing source for the nebula.

Sh2-13

Sh2-13, located above and to the right of Sh2-12 in the image, is a smaller open star cluster at an estimated distance of around 3,900 light years. Some scientists postulate that a single large star ionizes it and that this star is a runaway star ejected from the NGC 6383 cluster that ionizes Sh2-12.