In the past decade some 150 planets have been detected outside our Solar System, mostly via precise radial-velocity measurements of their host stars. Using an alternative method, transit searches have recently added 6 planets to the tally, and are expected to make more significant contributions in the future. The transit method is based on the detection of the tiny, periodic dip in the apparent brightness of a star when an orbiting planet passes in front of it. It requires intensive photometric monitoring of ??? 104 stars, with a precision better than ??? 1%. The 0.5 m Automated Patrol Telescope (APT) at Siding Spring Observatory, Australia, with its wide field of view and large aperture, is ideal for this task. This combination is also somewhat unique among telescopes used in transit searches. Since 2001, the APT has been semi-dedicated to a search for extrasolar planets. In this thesis work, observing, data reduction and analysis procedures were developed for the project. A significant fraction of the initial effort was focused on reaching the required photometric precision. This was achieved by implementing a new observing technique, and robust data reduction software. In the first two years of regular observations (starting in August 2002), 8 crowded Galactic fields were monitored, with photometric precision reaching 0.2% for the brightest stars. We searched the lightcurves of the brightest stars (V <13) and selected 5 planet candidates. Follow-up photometry and spectroscopy revealed all of these to be eclipsing binary stars. To date, no planets have been detected by this project. A detailed Monte Carlo simulation of the observations, using the currently known frequency and properties of extrasolar planets, resulted in a low calculated detection rate, consistent with the lack of detections. Using this simulation, we have investigated the observational and target star/planet parameters that determine the sensitivity of transit searches. The results highlighted the factors limiting our detection rate, and allowed us to significantly improve our observing strategy. According to the simulations, we should now detect ??? 2 planets per year. This will increase by a factor of a few when a new camera, currently under construction, is installed on the APT in early 2006.
| Identifer | oai:union.ndltd.org:ADTP/225450 |
| Date | January 2005 |
| Creators | Hidas, M??rton Gergely, Physics, Faculty of Science, UNSW |
| Publisher | Awarded by:University of New South Wales. School of Physics |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | Copyright M??rton Gergely Hidas, http://unsworks.unsw.edu.au/copyright |
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