sábado, 29 de octubre de 2011

Astrophysics - Planet-Killing Supermassive Black Holes the Cause of Mysterious Zodiacal Dust

Sag2cann (1)
Vast clumps dust shrouds that obscure about half of supermassive black holes could be the result of high speed roller-derby crashes between planets and asteroids, according to a new theory from an international team of astronomers, led by Sergei Nayakshin of the University of Leicester. 
Collisions between these rocky objects would occur at colossal speeds as large as 1000 km per second, continuously shattering and fragmenting the objects, until eventually they end up as microscopic dust.

An example of this phenomenon  is the 'light echo' of dust illuminated by a nearby star V838 Monocerotis as it became 600,000 times more luminous than our Sun in January 2002, which was  believed to have been caused by a giant collision between two stars or a star and a planet.
Collected data indicates that about 50% of them are hidden from view by mysterious clouds of so-called zodiacal dust, known to originate from collisions between solid bodies such as asteroids and comets. The scientists suggest that the central regions of galaxies contain not only black holes and stars but also planets and asteroids.
Dr. Nayakshin points out that this harsh environment - radiation and frequent collisions - would make the planets orbiting supermassive black holes sterile, even before they are destroyed.
"Too bad for life on these planets", he says, "but on the other hand the dust created in this way blocks much of the harmful radiation from reaching the rest of the host galaxy. This in turn may make it easier for life to prosper elsewhere in the rest of the central region of the galaxy."
"We suspect that the supermassive black hole in our own Galaxy, the Milky Way, expelled most of the gas that would otherwise turn into more stars and planets", he continues, "Understanding the origin of the dust in the inner regions of galaxies would take us one step closer to solving the mystery of the supermassive black holes".
Image at top of page shows the Sagittarius Dwarf Elliptical Galaxy  dwarf elliptical galaxy is being ripped by tidal forces into long streams of stars that will eventually be merged into the Milky Way
Image credit: Gabriel Pérez Díaz, Martínez-Delgado et al, 2003  and 2001, University of Geneva.
Source: The Daly Galaxy - ras.org.uk

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