SuperWASP – the project that recently discovered the five-star system
Discovery of a five-star system containing two eclipsing binary stars and a fifth lonely star made the headlines recently because of the rarity of such system and also because of the project from which the data was used that led to the discovery of such a rare system – SuperWASP.
SuperWASP is basically a project that is enabling scientists to search for exoplanets orbiting distant stars. Aptly named Super Wide Angle Search for Planets, the project detects planets by looking for ‘transits’ of planets in front of its parent star. This transit temporarily obscures some of the host star’s light, which can be detected from the Earth as a slight dimming of the star’s luminosity.
That’s what SuperWASP does! It constantly monitors the brightness of the stars in its field of view and alerts astronomers of any variations that may be due to the presence of a planet.
The SuperWASP observatories each consist of an array of 8 cameras, backed with a high-quality CCD (charge-coupled device). These cameras are extremely wide field – upto 2000 times greater than a conventional astronomical telescope. The cameras continuously image the night sky, each camera capturing up to 100,000 stars per image (this many are needed to stand any chance of detecting transiting planets). This amounts to over 50 gigabytes of observational data per night, per observatory, which is automatically processed by our custom built computer ‘Pipeline’.
The ‘Pipeline’ first reduces the images by removing errors such as variations in pixel sensitivity, dirt/scratches on the lenses, noise etc. This is done by comparing the images to special calibration images including Flat-field; Bias; and Dark-current.
The ‘pipeline’ then examines the images and matches each star with an astronomical catalogue of stars to identify them. Finally a complex photometric analysis is performed to measure the brightness of every star, the results of which are stored in the project database hosted by the University of Warwick.
When sufficient observations have been made (over several months), we perform searches for dips in brightness that might indicate the presence of a planet passing in front of a star. Unfortunately there are a large number of phenomenon, other than planets, that can cause changes in stellar brightness.
Very careful analysis is needed to verify the presence of a planet which is performed with the help of our collaborators from the Geneva Planet Search group. To confirm the presence of the planet they use sensitive spectrographs to measure the minute shift in position of the star as the planet orbits around.
Once confirmed, astronomers can then use large instruments such as the Hubble and Spitzer space telescopes to study these worlds.