Search for the heart of the matter
Article Abstract:
A black hole has such strong gravity that even light cannot escape. Its escape velocity is 300,000 km/sec: the speed of light. It is practically impossible to find a black hole but one may be discovered by its gravitational effects. V404 Cygni was discovered in 1992 as a result of a burst of x-rays detected by the Japanese satellite Ginga in 1989. The Hubble Space Telescope discovered another black hole in the middle of a galaxy called M87. The centre stars of M87 are packed 500 times more densely than other galaxies, held together by the gravity of a black hole which weighs 2.5 billion times the mass of the sun.
Publication Name: The Independent
Subject: Retail industry
ISSN: 0951-9467
Year: 1992
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Bright lights at the heart of Hercules
Article Abstract:
A large cluster of stars, M13, in the constellation of Hercules, is visible in June. It was formed 15 billion years ago. Each globular cluster has over 100,000 stars, so appears very bright. They are fossils which aid measurement of our galaxy's age. The galaxy's centre is 25,000 light years from the Sun. Electronic light detectors take measurements which show that the clusters have a range of ages, so the galaxy may have been created by a million small quantities of gas rather than by one huge gas cloud.
Publication Name: The Independent
Subject: Retail industry
ISSN: 0951-9467
Year: 1992
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How galaxies go bananas
Article Abstract:
The Hubble Space Telescope is transmitting extremely unusual images of the universe as a result of the influence of a natural distoring lens in space. Its new image of Abell 2218 is the best gravitational lens ever seen by astronomers, containing 120 different mirages. It makes background galaxies visible, showing them as they were when the universe as one-quarter of its present age.
Publication Name: The Independent
Subject: Retail industry
ISSN: 0951-9467
Year: 1995
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