Hunting for "Extrasolar Earths" via the Near Infared Transit Method
(Pinfield, Barnes, Jones, Napiwotzki)
Pinfield leads a large scale infrared transit survey searching for planets around cool stars. The survey uses the Wide-field Camera on the UK Infrared Telescope to monitor the brightness of many thousand M stars and searches for the characteristic periodic decrease in brightness as a planet passes in front of its host star.
Cool star planet-scape, by J. Pinfield, 2009, property of the RoPACS network at the University of Hertfordshire: A terrestrial planet orbits a cool red star. A small cratered moon is also seen in orbit around the planet. In its close orbit the planet is tidally locked to the star with the same hot side always in day light. The other side of the planet is cold, dark and icy. In between these two extremes lies the terminator region in which an ambient climate and liquid water have taken hold.
Other transit surveys use optical light, and are sensitive to planets transiting stars similar to the Sun. Cooler M dwarf stars are much fainter and 5-10 times smaller, and the transit technique is thus more sensitive to smaller planets around M stars, that could have lower temperatures and may be in the habitable zone. With 100+ nights of observations the survey has built up to a critical sensitivity at which new planets can be found.