Article Posted on : - May 06, 2010

The Abell 315 galaxy cluster. An ESO Photo

PARIS (BNS): A massive galaxy cluster, containing myriads of galaxies and equaling the size of a full Moon, has been detected by astronomers in the constellation of Cetus (the Whale).

The huge galaxy cluster – Abell 315 – captured by the European Southern Observatory's Wide Field Imager telescope, is located about two billion light-years away from Earth.

Dominated by dark matter, the new-found assembly of galaxies could only be a ‘tip of the iceberg’ as the cluster deflects light from background galaxies, thereby distorting their observed shapes slightly, ESO said.

The presence of dark matter in a galaxy cluster can be found from its gravitational effect which acts on the light emitted from galaxies behind the cluster like a ‘cosmic magnifying glass’, bending the trajectory of the light and thus making the galaxies appear slightly distorted.

By observing and analysing the twisted shapes of such background galaxies, astronomers can infer the total mass of the galaxy cluster responsible for such distortion.

In the case of Abell 315, astronomers, after studying the shapes of around 10,000 faint galaxies, have estimated its mass as over a hundred thousand billion times the mass of Sun.

The new Wide Field Imager picture, while capturing a wide cosmic field, has also thrown light on few objects much smaller than galaxies and galaxy clusters, and much nearer to Earth. These objects are stars belonging to the Milky Way galaxy, and several asteroids lying in the main asteroid belt located between the orbits of Mars and Jupiter, ESO said.