14 December 2011
from BBC Website
Simulation of cloud path around black hole (ESO/MPE/Marc Schartmann)
Simulations suggest that the cloud will be ripped to bits
and partially swallowed by the black hole
Researchers have spotted a giant gas cloud spiraling into the
super-massive black hole at our galaxy's centre.
ESO images of gas cloud
Reviews of existing pictures from the VLT
show the cloud speeding up in recent years
Our local super-massive black hole, dubbed
Sagittarius A*, lies
about 27,000 light-years away, and has a mass about four million
times that of our Sun.
It is likely that about half of the
cloud will be swallowed up, with the remainder flung back out into
Supermassive Black Hole and Gas Cloud
Supermassive Black Hole at The Galactic Center
Measurements of stellar orbits provide compelling evidence that the compact radio source Sagittarius A* (Sgr A*) at the Galactic Centre is a black hole four million times the mass of the Sun.
With the exception of modest X-ray and infrared flares, Sgr A* is surprisingly faint, suggesting that the accretion rate and radiation efficiency near the event horizon are currently very low. Here we report the presence of a dense gas cloud approximately three times the mass of Earth that is falling into the accretion zone of Sgr A*.
Our observations tightly constrain the cloud’s orbit to be highly eccentric, with an innermost radius of approach of only ~3,100 times the event horizon that will be reached in 2013.
Over the past three years the cloud has begun to disrupt, probably mainly through tidal shearing arising from the black hole’s gravitational force.
The cloud’s dynamic evolution and radiation in the next few years will probe the properties of the accretion flow and the feeding processes of the super-massive black hole.
The kilo-electronvolt X-ray emission of Sgr A* may brighten significantly when the cloud reaches pericenter. There may also be a giant radiation flare several years from now if the cloud breaks up and its fragments feed gas into the central accretion zone.