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New technique for ‘weighing’ black holes   The nature of Ultra Luminous X-ray (ULX) sources remains controversial, but many astronomers think that some or most of these objects consist of an intermediate-mass black hole that accretes matter from a companion star.
Recent evidence suggests that a ULX in the galaxy NGC 5408 has a black hole of about 2 000 solar masses.  This artist’s impression depicts a binary system akin to Cygnus X-1. It consists of a blue supergiant star (right) and a black hole.
The black hole is surrounded by a gaseous accretion disk that is fed by the star. Some black holes emit jets along the polar axis, as shown here. Release date: 3 August 2007 |