Extrasolar Planets and Brown Dwarfs
PhD Projects
Discovering Y dwarfs from the WISE observatory
David Pinfield, Ben Burningham
David Pinfield leads a project in search of the faintest Y dwarfs detectable by NASA's orbiting WISE telescope. Y dwarfs are brown dwarfs, star-like objects that cool and fade with time. With temperatures of 300-500K or lower, Y dwarfs share many characteristics with giant planets and the coolest known example has a temperature of ~25 C (~room temperature). WISE has scanned the whole sky in the mid-infrared where very cool brown dwarfs are brightest, and in 2011 the US WISE-team discovered the first Y dwarfs. Our approach of searching for fainter Y dwarfs is more difficult, but has the potential to yield cooler and/or closer objects. The student will join the programme and take part in the process of followup and analysis leading to new discoveries. Also the student will refinements the new search methods to identify even fainter WISE objects. It is possible that WISE could reveal a Y dwarf within the distance of Proxima Centauri - currently the Sun's nearest neighbour.
Planet or brown dwarf? - characterising the coolest companions
David Pinfield, Avril Day-Jones
Very cool companions are excellent test-beds that help astronomers understand the physics of ultracool atmospheres, and can have a variety of provenance. They may be brown dwarf companions that formed in situ. Alternatively they may be giant planets that migrated out to large orbits. They may even be giant planets being ejected from their parent stars due to some dynamical interaction. The student will develop methods to identify such systems in the UKIDSS and fast-growing VISTA surveys, and define techniques to differentiate between brown dwarf and giant planets through their emitted spectra. Statistical assessment will also contribute to discoveries from this project.
Searching for Earth+Jupiter-like systems in Kepler
David Pinfield, Phil Lucas
Kepler is a NASA space-based observatory that searches for transiting planets with unparalleled accuracy. A transit occurs when a planet partly eclipses its host star, and Kepler is monitoring the brightness of 100,000 stars for such events, revealing a plethora of new planets to date. The Kepler database is just about to release an expanded baseline of data giving sensitivity to longer period orbits. This project will take advantage of the new data by developing techniques to identify transiting cold giant planets (like Jupiter) out beyond the frost line. A tailored study of these systems will then be made to search for smaller planets closer into the host star, including potentially Earth-like planets. Such systems could be critical as possible hosts of terrestrial planets with surface oceans, since the gravity of cold giant planets is thought to be responsible for transferring water-ice (mainly comets) inwards where they may collide with terrestrial worlds.