This is Pismis 24-1 (HDE 319718), a region with spectacular diversity, beginning with its open cluster of neighboring stars, called Pismis 24. Together, they are centrally located within the diffuse “War & Peace” nebula (more formally known as NGC 6334), which is located approximately 8,150 light-years from Earth in the constellation of Scorpius.
Interestingly, Pismis 24-1 is one of the top candidates for the coveted title of being the “Milky Way Stellar Heavyweight Champion” because, when it was initially discovered several years ago, astronomers thought the area was powered by a single star that was about 300 times more massive than the sun. This conclusion was based on standard stellar models, in addition to its brightness and distance, but now there is a general consensus among the astronomical community that there are three stars embedded in the nebula. Each of the stars about 100 solar masses, putting them at the more massive end of the solar spectrum.
The interesting contrast of colors in this nebula is largely due to ionization taking place between the hydrogen in the nebula and a massive blue star that’s spitting out ultraviolet radiation, which creates the bubble seen here. As lovely as it may be to observe, the presence of the gas makes it all the more difficult to get a closer peek at the activity going on with the stars embedded inside the nebula.
You can download a larger version of this image, as well as find a zoomable version, here.