Mysteries of the stars deepen

The European Space Agency's X-ray multi-mirror satellite, known as XMM-Newton. ESA

Swiss astronomers, who are investigating the mysteries of the universe, have found that questions rather than answers lie in the stars.

This content was published on January 12, 2001 minutes

Astrophysicists at the Paul Scherrer Institute near Zurich have made a baffling
discovery while examining stars, some 37 light years away.

Contrary to all expectations, the composition of the stars' atmosphere appears
to be totally unlike that of the sun.

"We found a composition that is very different from what we expected," says project leader, Manuel Güdel.

"We would have expected to see a lot of iron and much less neon but what we found was a lot of neon and not so much iron. Now we are looking for answers."

The Paul Scherrer Institute is part of an international team evaluating data from the European Space Agency's X-ray multi-mirror satellite, known as XMM-Newton.

The satellite, which was launched in 1999, is the most powerful X-ray telescope ever placed in orbit and scientists are sure that the 10-year mission will help solve many cosmic mysteries from black holes to the formation of galaxies.

However, forced to rethink their theories about the atmospheric composition of stars, scientists have come up with a number of theories.

"Probably electric or magnetic fields are responsible for transporting those elements into the atmosphere of the star and the exact theory is not really
known at all for the stars we observed," said Güdel. "We will certainly look into effects due to electric fields and magnetic fields."

With its wafer-thin X-ray mirrors peering into deep space, XMM-Newton is expected to considerably increase our knowledge of very hot objects created when the universe was very young.

But in the meanwhile, it's raising more questions than answers than answers.

"The temperatures we observed in these stellar atmospheres are much higher than in the solar atmosphere," Güdel said.

"Imagine that the solar surface has a temperature of about 6,000 degrees and the stars that we observe have temperatures even less than that on the surface. But the atmospheres are as hot as 20 million degrees, and we don't understand why. There is no good explanation."

by Vincent Landon

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