Monday, 15 October 2012

Planet Hunters

Just been reading the latest extrasolar planet news. The newly publicised planet PH1 is extremely cool for two reasons. Firstly, it was discovered by two volunteers at, and secondly, it's got four suns!

PH1 is a Neptune-sized planet in a system around 5000 light years distant. The planet orbits a binary star - pretty fantastic in itself, seeing that such circumbinary planets were only confirmed to be possible a few years ago. Now, that binary pair, and beyond PH1 itself, orbit two more stars, in a second binary pair at a distance of roughly 1000 AU.

This is described as a 'hierarchical quadruple star system" featuring a planet orbiting an eclipsing binary. This is unexpected. When the two volunteer astronomers, K. Jek and R. Gagliano, reported their findings to Planethunters, the professionals got on the case and took a proper look at the system, confirming the analysis. They were understandably dubious of such a finding, since common consensus holds that such a system is impossible. The combined gravitational pulls of the four stars would be expected to tear the planet apart. Yet, there it is, happily orbiting one pair primarily and the next secondarily (much as the Moon orbits the Earth, and the Earth-Moon system orbits the Sun).

It's all a bit of a headscratcher. Plenty more information at io9 and

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