University of Leicester eBulletin

Leading Lights in Search for New Planets

March 2002

No 55  

University of Leicester astronomers hope to be the first to see a planet in a nearby star system.

Analysis of white dwarfs - dimly glowing stars at the end of their lives - could provide clues of new worlds out there.

Although more than 80 planets outside the Solar System have been detected, no-one has ever seen one. All were found indirectly by observing the "wobble" their gravity imparts on their parent stars.

Now Dr Matt Burleigh, of the University's Department of Physics and Astronomy, is hoping to use white dwarfs as a method of locating new planets.

He said: "Actually seeing planets orbiting a star is extremely difficult because they are so faint. It is like trying to find a firefly flitting in front of a car headlight."

It is estimated the it could take 15 years for NASA and the European Space Agency to image planets around normal, Sun-like stars. But Dr Burleigh believes that white dwarfs could provide the necessary clues.

He said: "White dwarfs are burned out remnants of old stars which have expanded into "red giants", thrown off their outer layers, and collapsed. Typically, they are 10,000 times less luminous than the Sun.

"Although a swollen red giant would devour nearby planets, those further out would spiral outwards and survive.  We think that planets more than five times the Earth's distance from the Sun will survive right through to the white dwarf phase," said Dr Burleigh.

He has been awarded time on the new twin eight-metre Gemini telescopes in Hawaii and Chile, and is starting to look at 50 nearby white dwarfs using near infra-red light wavelengths, which should provide the best chance of finding a planet. "Since 90% of stars evolve into white dwarfs, planets should be just as common around them as around other stars", says Burleigh. That could mean more than 10% of white dwarfs have planets. "Actually imaging a planet around another star would be fantastic," said Burleigh, "But at this stage I have no idea what we're going to see."

For more information, contact Dr Matthew Burleigh, telephone +44 (0)116 252 2077 XRA Astronomy Group Fax +44 (0)116 252 3311 Department of Physics and Astronomy, mbu@star.le.ac.uk University of Leicester www:http://www.star.le.ac.uk/~mbu/  Leicester, LE1 7RH ENGLAND Mobile: 07941 303519 .

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