Three researchers behind the discovery that our Universe's expansion is accelerating have been awarded this year's Nobel prize for physics. Saul Perlmutter and Adam Riess of the US and Brian Schmidt of Australia will divide the prize.

The trio studied what are called Type 1a supernovae, determining that more distant objects seem to move faster. Their observations suggest that not only is the Universe expanding, its expansion is relentlessly speeding up.

Prof Perlmutter of the University of California, Berkeley, has been awarded half the 10m Swedish krona (£940,000) prize, with Prof Schmidt of the Australian National University and Prof Riess of Johns Hopkins University's Space Telescope Science Institute sharing the other half.

The Nobel prizes have been given out annually since 1901, covering the fields of medicine, physics, chemistry, literature and peace.

Monday's award of the 2011 prize for physiology or medicine went to Bruce Beutler of the US, Jules Hoffmann from France and Ralph Steinman from Canada for their work on immunology.

This year's chemistry prize will be announced on Wednesday, BBC News reported.