UStAPS -- University of St.Andrews Planet Search

St.Andrews Astrophysics
staff: Prof.Keith Horne , Prof.Andrew Collier Cameron ,
Postdocs: Dr.Steve Kane , Dr.Tim Lister , Dr.Martin Dominik ,
PhD Students: Chris Leigh , Dan Bramich , Khalid Alsubai , Ben Hood.
Former students: Rachel Street , Yianni Tsapras , Colin Snodgrass .

HOT JUPITER SHADOWS: Doppler surveys show that 1% of nearby main sequence stars host "Hot Jupiters" in 3-4 day 0.05 AU orbits. 10% of these will have orbits close enough to edge-on for the planet to transit in front of the star. Thus 1 in 1000 main sequence stars should "wink" every 3-4 days. Jupiter transiting the Sun produces a 1% wink -- easy to detect by differential CCD photometry. Lower mass main sequence stars are smaller, making their winks even deeper. There are many transit searches underway worldwide. St.Andrews is pursuing both Deep and Wide transit searches.
DEEP SURVEY: We use the wide-field CCD camera on the 2.5m Isaac Newton Telescope to search for hot Jupiters transiting faint stars (18 to 22 mag) in Milky Way open cluster fields (NGC 6819, 7789, 6940).
WIDE SURVEY: We use small wide-angle CCD cameras to discover Hot Jupiters transiting relatively bright stars, down to 13th mag. St.Andrews is a leading member of the SuperWASP Consortium. . We are currently analysing data from the prototype WASP0 . camera on three fields, in Taurus, Draco, and Pegasus. The first SuperWASP camera was commissioned on La Palma in fall 2003, and will begin routine robotic operations in spring 2004. The SuperWASP consortium has secured funding for 2 additional cameras that will triple the speed of the wide-angle hot jupiter search.
MICROLENSING SEARCH FOR COOL PLANETS: St.Andrews is hunting cool planets using gravitational microlensing. The "cool zone" from 1-5 AU is most sensitively probed for planets by intensive monitoring of Galactic Bulge microlensing events. The OGLE III experiment finds 400-500 such events every year. As leading members of the PLANET collaboration, we monitor many of the most promising microlensing events to search for brief anomalies caused by cool planets. Each year a handful of anomalies are found (e.g. OB-2002-055 ) but usually without the intensive monitoring needed to characterise the cool planet mass. In the 2004 microlens season (Jun-Aug) we will use the UK's new 2m robotic Liverpool Telescope on La Palma, to intensify the coverage of microlens events. We are also proposing to purchase time on the Faulkes Telescopes (Maui Hawaii and Siding Springs Australia), linking these with the LT to form RoboNET 1.0. The next step is REX (as yet unfunded), deploying additional 2m scopes in Chile and South Africa. REX enables a sensitive 3-4 year search for cool Earths by observing >1000 microlens events with hourly sampling. This is the only known ground-based technique that is capable of discovering other Earths.
REFLECTIONS FROM HOT JUPITER ATMOSPHERES: St.Andrews pioneered a Doppler imaging technique to detect starlight reflected from the atmospheres of Hot Jupiters. Hot Jupiters intercept and reflect only 1E-5 to 1E-4 of the incident starlight. However, the reflected light has a Doppler shift, ~100 km/s, due to the orbital motion of the planet. We take hundreds of high S/N echelle spectra, recording the velocity profiles of thousands of stellar absorption lines, plus very faint shifted copies from the reflected starlight. We model and subtract the starlight spectrum, and then use a matched filter to extract the signature of the orbiting planet from the noisy residuals. We thereby measure the planet's orbit velocity, and hence the orbital inclination and the planet mass, the planet's albedo times radius squared, the albedo spectrum, and the phase function. More details .

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Keith Horne (kdh1@st-andrews.ac.uk)