Compass and scale image of M87 jet

M 87 is a supergiant elliptical galaxy, about 55 million light years from Earth. The galaxy has a featureless, ellipsoidal shape and is the second brightest galaxy in the nothern Virgo Cluster.

In the center of the galaxy a supermassive black hole is located, which is also the main component of its active galctic nucleus. Caused by the black hole and its accretion disk a relativistic jet emerges 5000 light years from the nucleus of the galaxy.

Within the Jet the space telescopes Hubble and Spitzer detected a knot, designated HST-1. This knot is about 210 light years from the core. By 2006, the X-ray intensity of this knot had increased by a factor of 50 over a four-year period.