24 October 2008

Distant stars send good vibes

Agence France-Presse
French astronomers have measured vibrations from distant stars for the first time, a technical feat that could also help answer questions about climate change caused by solar activity here on Earth.
Vibrating star

Illustration of a stellar global oscillation shaking the whole star interior and thus carrying information on it. Yellow refers to maximum temperature variations due to oscillations. Credit: Aarhus University/S. Frandsen

PARIS: French astronomers have measured vibrations from distant stars for the first time, a technical feat that could also help answer questions about climate change caused by solar activity here on Earth.

Using an orbital telescope called CoRoT, launched in December 2006 by the European Space Agency, the researchers analysed oscillations from three stars that result from nuclear fusion which shakes the stellar interior. They report the find today in the U.S. journal Science.

The stars measured are all between 1.2 and 1.4 times more massive than the Sun, and located between 100 and 200 light years away. The study revealed that all three are much hotter than the Sun and have vibrations around 50 per cent more fierce, though still far less than had been predicted.

Solar seismology

“The Sun is a simple star, it is old and lost its memory. You don’t learn very much by looking at it,” said co-author Annie Baglin at the National Centre for Scientific Research (CNRS) in Meudon, France, explaining why the researchers are measuring the vibrations of other stars.

The initial discovery of oscillations in our Sun in the late 1970′s led to the creation of “solar seismology,” which has since been used to measure the movement and transport of heat around the Sun. Solar seismology led to rapid progress in understanding the Sun’s internal structure, but eventually researchers hit a wall.

Accurate measurements of solar and stellar oscillations require the collection of precise data from long, uninterrupted sequences of observations, making ground-based study impossible.

Understanding how this mechanism works, using the CoRoT (COnvection ROtation and planetary Transits) telescope, is now shedding light on variations in solar radiation that, even if slight, can have major impacts on Earth’s climate, inflicting periods of icing or warming.

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