14 May 07

Astronomers have witnessed galaxies giving birth to their first stars just over a billion years after the Big Bang. The multinational team, led by Dr Aprajita Verma from Oxford Astrophysics, captured these young galaxies in the earliest stages of star formation and their findings are shedding new light on how our galaxy and its neighbours evolved.

'It is exciting to think that by analysing the light from these very distant galaxies we can directly study the first star formation episodes that happened so soon after the Big Bang' said Dr Verma, lead author of a report on the work recently published in Monthly Notices of the Royal Astronomical Society.

The astronomers were able to see what galaxies similar to those around today were like over 12 billion years ago. They found that, in their youth, galaxies of this kind have a very high density of stars - comparable to the centres of only the most massive of today's galaxies. The young galaxies they observed are also forming stars at a surprisingly high rate - up to 100 times the rate of The Milky Way, our own galaxy.

The team were able to achieve their results by analysing the relative brightness of each galaxy across the spectrum from visible to infrared light. The galaxies involved are small compact structures that emit light of a different colour to less distant galaxies, and it is this difference that enables astronomers to spot galaxies one billion years after the Big Bang.

Dr Verma said: 'While some of these galaxies were mature and had been forming stars for several hundred million years, the majority had been forming stars for a far shorter period, just tens of millions of years - in essence we were seeing these galaxies in the first flush of youth.'