Using the Wide Field Imager on the MPG/ESO 2.2-m telescope at ESO’s La Silla Observatory, astronomers captured an extraordinary image of a young open star cluster called NGC 2367.

NGC 2367, otherwise known as C 0718-218, was discovered by Sir William Herschel on 20 November 1784. It is a bright star cluster located in the constellation Canis Major, around 7,175 light-years away.

The cluster is roughly 6 million years old. Most of its stars are young and hot and shine with an intense blue light.

Open clusters like this one are a common sight in spiral galaxies like our Milky Way Galaxy, and tend to form in their host’s outer regions. On their travels about the galactic center, they are affected by the gravity of other clusters, as well as by large clouds of gas that they pass close to.

What is more unusual is that, as you begin to pan out from the cluster and its nebula, a far more expansive structure is revealed.

NGC 2367 and the nebula containing it are thought to be the nucleus of a larger nebula, Brand 16, which in turn is only a small part of a large star-forming supershell, known as GS 234-02.

The supershell is a vast structure, spanning hundreds of light-years. It lies towards the outskirts of our Galaxy.

It began its life when a group of particularly massive stars, producing strong stellar winds, created individual expanding plasma bubbles.

These neighboring bubbles eventually merged to form a superbubble, and the short life spans of the stars at its heart meant that they exploded as supernovae at similar times, expanding the superbubble even further, to the point that it merged with other superbubbles, which is when the supershell was formed. The resulting formation ranks as one of the largest possible structures within a galaxy.