Shot-in-the-dark astronomy finds super-Earth

'Super-Earth' MOA-2012-BLG-505Lb is about 24,000 light years away from earth.

'Super-Earth' MOA-2012-BLG-505Lb is about 24,000 light years away from earth.

Nasa is adopting a planet hunting technique created by Kiwi scientists.

Called gravitational microlensing, it helped Auckland and Massey University scientists Associate Professor Ian Bond and Dr Nick Rattenbury find a new giant planet orbiting a far flung star this year with Canterbury's Mt John telescope - a 'super-Earth.'

Estimated to be two to five times the size of Earth, the "very cold and icy" planet is about 24,000 light years away, and is believed to orbit a dim star weaker than our own sun, Rattenbury said.

Canterbury's Mt John Observatory MOA-II telescope.

Canterbury's Mt John Observatory MOA-II telescope.

But the discovery of the latest planet was partly by chance.

The pair found out they had actually captured the planet in observations made back in 2012. However it was not till this year as they were sifting through all their data that they realised what they had.

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"We'd started a new way of observing, about once a night we used to observe very infrequently different directions shifting the telescope from position to position, then we changed our strategy to a small number of [positions] lots of times a night," Rattenbury said.

"This event [discovery of the super-Earth] lasted only 10 days, they usually last 30 days on average."

Unlike planets revealing themselves by directly blocking out star light, gravitational microlensing detects perceived increases in light caused by a gravitational field - the gravitational field betrays the presence of a planet.

"The chances of one of these things lining-up [with the telescope] is about a million-to-one," Rattenbury said.

Sifting-through years of accumulated data in 2017, the scientists discovered they'd actually detected the planet back in 2012, Rattenbury said.
What's exciting about discovery is that it adds to evidence showing planets can exist close to the centre of our galaxy, the Milky Way, Rattenbury said.
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Since the 1990's about 25 planets have been found using gravitational microlensing, about another 14 are yet to be confirmed, he said.

Albert Einstein first theorised the technique and the Kiwi scientists have helped turn it into a reality as part of the New Zealand/Japanese Microlensing Observations in Astrophysics (MOA) collaboration, using the University of Canterbury's MOA-II Mt John telescope.

Now NASA has adopted the gravitational microlensing technique developed by our scientists and will use it aboard its planned 2020 outer space Wide Field Infrared Survey Telescope.

As for the planet officially known as MOA-2012-BLG-505Lb, no one's in a hurry to name it and for now it will likely keep its "phone number" name, Rattenbury said.

The collaboration group's under peer-review paper, MOA-2012-BLG-505Lb: A super-Earth mass planet in the Galactic bulge, will be published in The Astrophysical Journal.

 - Stuff


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