First extragalactic exoplanet may have been found by gravitational microlensing

June 11th, 2009 - 2:06 pm ICT by ANI  

London, June 11 (ANI: A team of scientists has used gravitational microlensing to come up with a tentative detection of the first extragalactic exoplanet in Andromeda, our nearest large galactic neighbour.

In gravitational microlensing, a distant source star is briefly magnified by the gravity of an object passing in front of it.

This technique has already found several planets in our galaxy, out to distances of thousands of light years.

“Extending the method from thousands to millions of light years won’t be easy, but it should be possible,” said Philippe Jetzer of the University of Zurich in Switzerland.

According to a report in New Scientist, Jetzer and five colleagues simulated microlensing from the Andomeda galaxy, which is more than 2 million light years away.

They started by populating Andromeda with planets, assuming that they will have the same range of sizes and orbits as known exoplanets in our own galaxy.

“These are reasonable guesses, probably right within a factor of two,” Jetzer told New Scientist.

They then calculated how these planets might reveal themselves.

When a lensing star system drifts into our line of sight, it bends light from the background star, which appears to brighten and then fade again smoothly over a few weeks or months.

If the lensing star has a planet in tow, then the planet’s additional gravity can produce an uneven pattern of brightening and fading, or even add a brief flare lasting hours or days.

Looking at Andromeda, telescopes won’t be able to pick out individual background stars, but instead they could see a similar effect in the brightness of individual pixels, which may represent several stars - when a big star is lensed.

Next year, a group at the University Observatory of Munich will begin looking for microlensing events in Andromeda using a new 2-metre telescope on Mount Wendelstein in Germany.

They might just get lucky and spot the first planet in another galaxy. (ANI)

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