01 Apr 2008

Open University astronomers help to find 10 new planets

Image of the Euler (Swiss) Telescope dome

Image of the Euler (Swiss) Telescope dome

An international team of astronomers have used two batteries of cameras, one in the Canary Islands and one in South Africa, to discover 10 new planets in orbit around other stars (commonly known as extrasolar planets). The results from the Wide Area Search for Planets (SuperWASP) was made at the RAS National Astronomy Meeting (NAM 2008) in Belfast on Tuesday 1 April.

SuperWASP uses two sets of cameras to watch for events known as transits, where a planet passes directly in front of a star and blocks out some of the star’s light, so from the Earth the star temporarily appears a little fainter. The SuperWASP cameras work as robots, surveying a large area of the sky at once and each night astronomers have data from millions of stars that they can check for transits and hence planets. The transit method also allows scientists to deduce the size and mass of each planet.

Astronomers at The Open University have been key players in the SuperWASP consortium since its inception, providing funding and person-power to get the project started. They continue to play leading roles in the ongoing detection of extrasolar planets and their characterisation. OU Senior Lecturer Dr. Carole Haswell is leading follow-up observations of the WASP planets using the Hubble Space Telescope, working with her postgraduate students Becky Enoch and Andrew Carter to measure physical properties of the newly discovered extrasolar panets. In addition, OU Senior Lecturer Dr. Andrew Norton is leading work on identifying half-a-million new variable stars amongst the millions of objects in the SuperWASP archive, and his postgraduate student Stan Payne is developing automated computer neural networks to classify them. Drs. Haswell and Norton are also coordinating an exhibit at this year’s Royal Society Summer Exhibition that will showcase UK extrasolar planet research.

Each possible planet found using SuperWASP is then observed by astronomers working at the Nordic Optical Telescope on La Palma, the Swiss Euler Telescope in Chile and the Observatoire de Haute Provence in southern France, who use precision instruments to confirm or reject the discovery.

45 planets have now been discovered using the transit method, and since they started operation in 2004 the SuperWASP cameras have found 15 of them – making them by far the most successful discovery instruments in the world. The SuperWASP planets have masses between a middleweight 0.5 and a huge 8.3 times that of Jupiter, the largest planet in our Solar System. A number of these new worlds are quite exotic. For example, a year on WASP-12B (its orbital period) is just 1.1 days. The planet is so close to its star that its daytime temperature could reach a searing 2300 degrees Celsius.

Scientists have found more than 270 extrasolar planets since the first one was discovered in the early 1990s. Most of these are detected through their gravitational influence on the star they orbit – as it moves the planet pulls on the star, tugging it back and forth. However, making these discoveries depends on looking at each star over a period of weeks or months and so the pace of discovery is fairly slow.

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