出典:Wiktionary
出典:Wikipedia
出典:『Wikipedia』 (2011/07/03 05:13 UTC 版)
Messier 87 (also known as M87, Virgo A or NGC 4486) is a supergiant elliptical galaxy. It was discovered in 1781 by French astronomer Charles Messier. The second brightest galaxy within the northern Virgo Cluster, it is located about 53.5 million light years away from Earth. Unlike a disk-shaped spiral galaxy, Messier 87 has no distinctive dust lanes and it has an ellipsoidal shape. At the core is a supermassive black hole, which forms the primary component of an active galactic nucleus that is a strong source of multiwavelength radiation, particularly radio waves. A jet of energetic plasma originates at the core and extends out at least 5000 light-years.