Quasars: Astronomers find cast iron evidence of when first stars were born

Brussels, 13 May 2003

The latest observations of the distant corners of space have shed light on when the first stars were born, which European astronomers now believe was much earlier than previously thought.

A team of European and American astronomers, using the latest readings from the NASA/ESA Hubble space telescope, have made the remarkable find that stars may have first formed as early as 200 million years after the 'big bang'. As the universe is generally held to be at least 13 billion years old, this means that stars have spun in the cosmos since its infancy.

Astronomers from the European Space Agency (ESA) reached this conclusion when they noticed the presence of iron on three of the universe's most distant and ancient quasars – quasi-stellar radio sources believed to be powered by super-massive black holes.

Stars are, in effect, 'nuclear factories' that process lighter elements, such as hydrogen and helium, into progressively heavier ones. Scientists estimate that it takes a quasar some 700 million years before it produces iron. The light from the quasars – which had travelled for 12.8 billion years before reaching Hubble's spectrograph – had left them 900 million years after the Big Bang. By deducting the two figures, astronomers were able to calculate the age of the first stars.

"We believe that the iron we detected was created in the very first generation of stars which formed soon after the Big Bang," says Wolfram Freudling, head of the team who made the discovery.

Revising the origin of life

The detection of iron so early in the life of the universe has profound implications and may cause astronomers to revise some standing theories. "The presence of iron, and, by implication, all other lighter elements, shows that basic ingredients for planets and life were present, at least in some places, very early in the history of the universe," says Michael Corbin, a member of the ESA team.

These findings may also shed light on the dark enigma of black holes. According to an ESA press announcement, these new observations suggest that the first stars predated by hundreds of millions of years the super-massive black holes that power the quasar engines in the centres of galaxies.

"The creation of the black holes themselves still remains a mystery, although the birth date of the first stars may prove to be a very valuable clue," the statement read.

Contact: research@cec.eu.int

More information on this subject:

ESA press release

DG Research
http://europa.eu.int/comm/dgs/research/i ndex_en.html
http://europa.eu.int/comm/research/headl ines.html#04