Pismis 24

The star cluster Pismis 24 lies within the much larger emission nebula called NGC 6357, located about 8,000 light-years from Earth. The cluster is seen here above a small portion of the nebula. The gas below the stars glows through ionization caused by intense ultraviolet radiation from the massive young stars within the cluster. The strong radiation and stellar winds from from these blazing, blue-white stars also pushes the nebular material outward, creating one of many low-density bubbles within NGC 6357. One of the top candidates for the title of "Milky Way Stellar Heavyweight Champion" was once Pismis 24-1, a bright young star that lies in the core Pismis 24. This star was thought to have an incredibly large mass of 200 to 300 solar masses. Hubble Space Telescope measurements of the star, however, resolved Pismis 24-1 into two separate stars, and, in doing so, "halved" its mass to around 100-150 solar masses. For more information, visit: hubblesite.org/contents/news-releases/2006/news-2006-54.html

Credits: NASA, ESA and Jesús Maíz Apellániz (Instituto de Astrofísica de Andalucía, Spain); Acknowledgment: Davide De Martin (ESA/Hubble)