SNIPPETS - Rare system of five stars discovered

Rare system of five stars discovered

Astronomers have discovered a very rare system of five connected stars. The quintuplet consists of a pair of closely linked stars —binaries — one of which has a lone companion; it is the first known system of its kind. The pair of stars orbit around a mutual centre of gravity, but are separated by more than the distance of Pluto’s orbit around the Sun. The findings have been presented at the UK National Astronomy Meeting in Llandudno.

The unusual system lies 250 light-years away in the constellation Ursa Major. It was discovered in data gathered by the SuperWASP (Wide Angle Search for Planets) project. This uses relatively small and low-cost cameras in the Canary Islands and South Africa to image much of the sky every few minutes. Measurements of the brightness of individual stars are, over years, assembled into light curves - plots of brightness against time. When the stars pass in front of one another, they produce a regular pattern of pairs of dips in the light curve.

Data from the new system revealed the existence of two binary stars, one of which was a so-called contact binary. Co-author Dr Markus Lohr, from the Open University, said that these contact binaries were stars that orbit so closely they share an outer atmosphere.
The other star pair - a detached binary - has a separation distance of some three million km. The two binaries orbit in the same plane at a distance of 21 billion km. Follow-up observations of different wavelengths of light coming from the star system uncovered a fifth star, which is linked to the detached binary star.

“This is a truly exotic star system. In principle there’s no reason why it couldn’t have planets in orbit around each of the pairs of stars. Any inhabitants would have a sky that would put the makers of Star Wars to shame,” Dr Markus said. “There could sometimes be no fewer than five Suns of different brightnesses lighting up the landscape.”
Paul RINCON

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Crossbreeding can help survival
Mixing and matching corals of the same species from different latitudes could help coral reefs survive despite warming ocean temperatures, according to a new study. “Corals already have the genetic variance to adapt to changing temperature,” said Mikhail Matz, an assistant professor of integrative biology at the University of Texas at Austin.

“It’s just a matter of transporting these mutations from hot locations to locations that will be hot very soon because of global warming.” Mikhail and his colleagues studied corals from naturally warmer areas of the Great Barrier Reef in Australia and those in cooler water 300 miles to the south.

The researchers found that coral larvae with parents from the north, where waters are slightly warmer, were up to 10 times as likely to survive elevated temperatures in laboratory studies. They reported their findings in the journal Science.

Mikhail and his colleagues also found that when the coral from the north and south were crossbred, genes for heat tolerance could be passed on. “Not only is heat tolerance heritable, but it’s highly heritable,” Mikhail said.

Coral larvae move across waters naturally, and crossbreeding will occur anyway. Mikhail said humans could speed the process up by 10 to 20 years. He warned, though, that as the climate continues to warm, coral reefs still face threats. “This is not a magic bullet,” Mikhail said. “The existence of this gene variation buys us some time.”
Sindya N Bhanoo

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