Washington, August 23 : The Universe is forming fewer stars than it did
over 8 billion years ago and scientists believe that it is because
galaxies are, quite literally, running out of gas.

Dr Robert Braun (CSIRO Astronomy and Space Science) and his colleagues
used CSIRO's Mopra radio telescope near Coonabarabran, NSW, to study
far-off galaxies and compare them with nearby ones.

Galaxies at this stage of the Universe's life appear to contain
considerably more molecular hydrogen gas than comparable galaxies in
today's Universe, the research team found.

"Star formation has used up most of the available molecular hydrogen gas," Dr Braun said.

After stars form, they shed gas during various stages of their lives, or in dramatic events such as explosions (supernovae).

This returns some gas to space to contribute to further star formation.

"But most of the original gas-about 70 percent-remains locked up, having
been turned into things such as white dwarfs, neutron stars and
planets," Dr Braun said.

Dr. Braun blames the hypothetical dark energy that drives galaxies apart for the missing gas.

This accelerating expansion will have made it increasingly difficult for
galaxies to capture the additional gas they need to fuel future
generations of star formation, Dr Braun speculates.

The study will be published in the monthly notices of the Royal Astronomical Society. (ANI)