M82 is an excellent example of a starburst-type irregular galaxy.  Astronomers theorize the nearby spiral galaxy M81 passed very close to M82 approximately 600 million years ago .  The resulting gravitational interaction is likely responsible for some of the unusual properties observed in this interesting object.  Massive stars grouped in large concentrations are observed in the galaxy. The Hubble Space Telescope imaged M82 in infrared light revealing over 100 of these super star clusters ¹.  These clusters can be seen in my image as bright areas in the galactic disk.  The massive stars in these clusters consume their nuclear fuel on a very short time scale ending in violent supernova events.  These events expel large volumes of hot molecular gas and shock waves into interstellar space triggering additional star formation.  M82 is one of the sky's most luminous galaxies in the X-ray portion of the spectrum.  Visible in high energy images from the Chandra telescope, M82 has a huge central jet of very high-energy particles and and gas extending perpendicular to its cigar-shaped body.  The driving energy source is attributed to a high rate of super nova explosions which expel massive amounts of material into interstellar space and, in the case of M82, even into intergalactic space.  The central red colored feature is a hint of this violent behavior and is most probably highly energized hydrogen being ejected from these massive supernova explosions.  This strange and very interesting galaxy is the object of much study in the scientific community and many diverse theories explaining its perplexing properties abound.

Acknowledgments: My sincere thanks are extended to Dr. P. Clay Sherrod of the Arkansas Sky Observatory for his most interesting and informative communications concerning this subject and to Randy Nulman for his patient assistance and advice on processing this rather difficult object.

¹ http://www.seds.org/messier/more/m082_hst.html