NASA has released an image that’s stunning even by its standards of nebula NGC 6357. The colors are the result of a composition obtained by putting together X-ray data from  Chandra X-ray Observatory and the ROSAT space telescope, the infrared data from NASA’s Spitzer space telescope and optical data from the SuperCosmos Sky Survey.

NGC 6357, also known as the Lobster Nebula or the War and Peace Nebula, is a diffuse nebula, which is a nebula that has a considerable extension without defined borders, as well as an emission nebula, which is an interstellar cloud of ionized gas emitting light of various colors. It’s associated with big young stars forming what is called H II region, which indicates ionized hydrogen.

The NGC 6357 nebula includes at least three star clusters that contain young stars and many of them are massive and therefore very bright. Such stars emit huge amounts of radiation affecting the hydrogen content in interstellar gas clouds nearby stripping away its electrons ionizing it. That’s the reason why the gas clouds associated with massive stars form H II regions but they don’t last long in astronomical terms because those massive stars have a life of no more than some tens of millions of years.

Because the nebula NGC 6357 is about 5,500 light years distant from Earth we can see it at the peak of its activity and its evolution with a delay limited to a few thousand years and with many details. Its massive young stars are shining even at X-rays but they also come from areas where the gas is very hot. Inside NGC 6357 hundreds of X-ray sources were discovered and they provide a lot of information otherwise invisible at other frequencies of electromagnetic radiation blocked by dust and gas.

Putting together the X-ray data from Chandra and ROSAT (the purple colored areas), the Spitzer infrared data (orange areas) and the SuperCosmos Sky Survey optical data (blue areas), it was possible to get the final image which gives an idea of varied processes in place within the nebula NGC 6357. Inside it there are many young massive stars but also bubbles, voids created by radiation and materials swept away from the surface of massive stars but also by the tremendous power of supernovae.

This type of image that brings together observations at different frequencies is absolutely spectacular, but as always there’s also a scientific utility. Astronomers hope to better understand the characteristics of NGC 6357 and why within it some of the most massive stars ever discovered are forming.