Weekend Image: Supermassive Star Lights Up a Nebula

          

The breathtakingly beautiful Cocoon Nebula is located about 4,000 light years away toward the constellation of Cygnus. Hidden inside the Cocoon is a newly developing open cluster of stars dominated by a massive star in the center of the above image that opened a hole in an existing molecular cloud through which much of the glowing material flows. The same star, which formed about 100,000 years ago, provides the energy source for much of the emitted and reflected light from this nebula.

Massive stars shine steadily until the hydrogen has fused to form helium ( it takes billions of years in a small star, but only millions in a massive star), when it  becomes a red supergiant and starts off with a helium core surrounded by a shell of cooling, expanding gas. Over the next million years a series of nuclear reactions occur forming different elements in shells around the iron core.

When the core collapses in less than a second, it causes a supernova, in which a shock wave blows of the outer layers of the star. If the core -between 1.5 - 3 solar masses- survives, it contracts to become a neutron star. If the core is much greater than 3 solar masses, the core contracts to become a black hole.

Image Credits: Jean-Charles Cuillandre (CFHT), Hawaiian Starlight, CFHT