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The last cry of matter   Graphical depiction of gas swirling around a black hole before falling into it.  GRO J1655-40 is the second so-called 'microquasar' discovered in our Galaxy. Microquasars are black holes of about the same mass as a star. They behave as scaled-down versions of much more massive black holes that are at the cores of extremely active galaxies, called quasars. Astronomers have known about the existence of stellar-mass black holes since the early 1970s. Their masses can range from 3.5 to approximately 15 times the mass of our Sun.
Using Hubble data, astronomers were able to describe the black-hole system. The companion star had apparently survived the original supernova explosion that created the black hole. It is an ageing star that completes an orbit around the black hole every 2.6 days. It is being slowly devoured by the black hole. Blowtorch-like jets (shown in blue) are streaming away from the black-hole system at 90% of the speed of light.   The task of Integral, ESA's International Gamma-Ray Astrophysics Laboratory, is to gather the most energetic radiation that comes from space. The spacecraft was launched October 2002 and will help to solve some of the biggest mysteries in astronomy. Gamma rays are even more powerful than the X-rays used in medical examinations. Fortunately, the Earth's atmosphere acts as a shield to protect us from this dangerous cosmic radiation. However this means that gamma rays from space can only be detected by satellites. Integral is currently the most sensitive gamma-ray observatory ever launched. It detects radiation from the most violent events far away and from processes that made the Universe habitable. Last update: 26 October 2004 |