Supermassive black holes: the destroyers of worlds

Posted by fi17 at Nov 03, 2011 05:10 PM |
New theory from team led by University scientist proposes that huge black holes are surrounded by the crushed remains of dead planets
Supermassive black holes: the destroyers of worlds

Hubble image of ‘light echo’ of dust illuminated by V838 Monocerotis that became 600,000 times more luminous than our Sun in January 2002, believed to have been caused by a giant collision. image: NASA/ESA.

Astronomers and physicists have long suspected that supermassive black holes lurk in the heart of most galaxies - there's even one in our own back yard, in the centre of the Milky Way. These deep space monsters are often surrounded by a doughnut-shaped cloud of dust and gas - and this dusty cloud is the subject of a new theory proposed by Dr Sergei Nayakshin of our Department of Physics and Astronomy and his international team.

Dr Nayakshin believes that the dust is in fact the shattered remains of planets and asteroids that once inhabited the galactic core, along with stars and black holes. In the centre of the galaxy these rocky objects would have crashed into each other at high speeds - up to 1,000km per second. These collisions would shatter the planets and asteroids into ever smaller pieces, eventually reducing them to microscopic dust. But even before they're smashed to smithereens, these planets would be lifeless - rendered sterile by the harsh radiation emitted from the supermassive black holes they orbit around.

The dust around black holes often obscures them from view, but Dr Nayakshin believes this rocky cloud also shields the rest of the galaxy from the black holes' harmful radiation - indirectly making it easier for life to thrive on planet Earth. It turns out those poor planets didn't die for nothing.

The team's findings have been published in the journal Monthly Notices of the Royal Astronomical Society.