The transit method has now bagged its 13th and 14th planets, both of them ‘hot Jupiters’ so close to their stars that their orbits are two and two and one-half days respectively. That makes for temperatures well over 1800 degrees Celsius, and adds more data points in our improbable collection of massive planets that all but skim their stars as they race around their orbits. One of the new planets, called WASP-1b, is in the constellation Andromeda, and is thought to be 1000 light years distant. WASP-2b, in Delphinius, is some 500 light years away.
Behind the discovery is the UK consortium called SuperWASP — Wide Angle Search for Planets. The astronomers involved are surveying millions of stars from robotic observatories in the Canary Islands and in South Africa. Each observatory uses eight wide-angle cameras, with a field of view 2000 times greater than a conventional astronomical telescope. The goal is to detect the faint dimming of starlight that flags a planetary transit, visible in the ‘light curve’ of stars with a clear transit. In the case of WASP-1b and WASP-2b, the discoveries were later confirmed by radial velocity measurements.
Image: The transit detection process. As the planet passes in front of the star it produces a characteristic ‘light-curve’ whose shape is affected by the size and orbital distance (and hence orbital period) of the planet. SuperWASP constantly monitors the brightness of the stars in its field of view and alerts astronomers to any variations that may be due to the presence of a planet. Credit: SuperWASP.
I see that the SuperWASP team is still working with 2004 data (although its Web site doesn’t make it clear when the data on these new planets were gathered), but they seem to have enough interesting light-curves to feel confident that their transit effort will produce big results. The work was announced at the Transiting Extrasolar Planets Workshop at the Max Planck Institute for Astronomy in Heidelberg on September 26. The paper, available as a preprint, is Cameron et al., “WASP-1b and WASP-2b: Two new transiting exoplanets detected with SuperWASP and SOPHIE,” which has been submitted to the Monthly Notices of the Royal Astronomical Society.