Gamma rays in the Heart of Cygnus

Cosmic rays are subatomic particles — mainly protons — that move through space at nearly the speed of light. In their journey across the galaxy, the particles are deflected by magnetic fields, which scramble their paths and make it impossible to backtrack the particles to their sources. Yet when cosmic rays collide with interstellar gas, they produce gamma rays — the most energetic and penetrating form of light — that travel to us straight from the source.

The Cygnus X star factory is located about 4,500 light-years away and is believed to contain enough raw material to make two million stars like our sun. Within it are many young star clusters and several sprawling groups of related O- and B-type stars, called OB associations. One, called Cygnus OB2, contains 65 O stars — the most massive, luminous and hottest type — and nearly 500 B stars. These massive stars possess intense outflows that clear out cavities in the region's gas clouds. A tangled web of shockwaves associated with this process impedes the movement of cosmic rays throughout the region. Cosmic rays striking gas nuclei or photons from starlight produce the gamma rays Fermi detects.

The release on NASA.gov is here.