Saturday, June 15, 2013

Space: Discovery of stars with changing light - Metronews

space has not finished to unveil its mysteries. It has long been known that the brightness of the stars could fall over time, be pulsating or variable. But this is the first time a group of astronomers confirmed the existence of stars with changing light according to a well-established pattern. These were observed by a team of Swiss scientists from the La Silla Observatory in Chile, and an article on the subject was published in the journal Astronomy and Astrophysics , released Wednesday.

These

Swiss monitored for not less than seven years of stars in the stellar cluster NGC 3766, to 7000 light years away from Earth. They found that over time a small change in light of the order of 0.1% of estimated between two and twenty hours, depending on the observed star cycles. If brightness variations have been observed, it had never been done on such specific periods and also the stable frequency.

A periodic variation that changes everything

“The existence of this new class changing star is a real challenge for astrophysicists,” enthused Sophie Saesen, member of the Geneva Observatory. “The current theoretical models predict that their light is not supposed to vary periodically, so our efforts are to better understand the behavior of this new type of star.”

However, for now, it is not possible to determine the precise reasons for these variations. However, scientists have made some observations. First, these stars are “slightly warmer and brighter than the sun,” said the European Monitoring astral (ESO). Moreover, they appear with a rapid rotation: turning more than half of their critical speed (variable threshold at which a star becomes “unstable” and ejects material into space by centrifugal force .)

“Under these conditions, the rapid rotation will have a significant impact on their internal properties, but we are not yet able to model the variations in brightness,” said Nami Mowlavi, head of the scientific group that made this discovery particularly interesting.

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