An Antarctic Search for Transiting Extrasolar Planets
by Yan Fantei-Caujolle - 19 April 2007
A new research domain has appear with the discovery of extrasolar planets. Although difficult, the method of detecting planets that transit in front of their stars is very profitable because, when combined with radial velocity measurements, it yields the radius and mass of the planets and therefore a constraint on their composition. Although France is at the forefront of transit detections with the COROT mission, it is relatively absent of ground-based programs to detect transiting extrasolar planets. Yet, the Concordia station at Dome C is run by France and Italy, and has been shown to be a site of exceptional quality due to the continuous winter night and the extremely promising photometric conditions. Dome C is probably by far the best site on Earth for the detection and characterization of extrasolar planets by transits.
We were able to show from theoretical studies and analyses of transit surveys that two crucial limitations to the detection of planets by transits are: 1/ The non-continuous duty cycle at mid-latitudes due to the day-night alternance, and the imperfect meteorology; 2/ “Systematic effects” that are linked to the interactions between external phenomena (variations of the temperature, humidity, airmass…) and the instrument, with characteristic periods of a fraction to several hours. These systematics are very poorly known and require a precursor project before a massive transiting planet survey program can be proposed for Dome C.
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