Black Holes in Small and Medium
Using data from the Rossi X-Ray Timing Explorer, scientists have found the smallest Black Hole yet identified. It is part of a binary system in galaxy XTE J1650-5000. The Black Hole has 3.8 times the mass of the Sun and would have an event horizon 24 km in diameter. These findings were presented Monday at the AAS High Energy Astrophysics Meeting.
Separately, astronomers have identified a medium-sized Black Hole 17,000 light-years away in the Omega Centauri cluster. This globular cluster, pictured above, contains 10 million stars that are among the youngest in the Universe. Scientists have long wondered how globular clusters formed. Some estimates have them older than the Universe itself! Researchers using the Gemini South and Hubble Space Telescopes conclude that Omega Centauri contains a Black Hole of 40,000 solar masses.
Since globular clusters are so old, this Black Hole could be primordial, formed soon after the Big Bang. We have also found galaxies containing supermassive Black Holes formed when the Universe was less than a billion years old. Size of a primordial Black Hole is limited by a horizon distance related to the speed of light. Massive Black Holes within ancient globular clusters are another indicator that c has changed.
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Labels: black holes