A MATCHED-FILTER METHOD FOR GROUND-BASED SUB-NOISE DETECTION OF TERRESTRIAL EXTRASOLAR PLANETS IN ECLIPSING BINARIES - APPLICATION TO CM-DRACONIS

The photometric detection of extrasolar planets by transits in eclipsi ng binary systems can be significantly improved by cross-correlating t he observational light curves with synthetic models of possible planet ary transit features, essentially a matched filter approach. We demons trate the utility and application of this transit detection algorithm for ground-based detections of terrestrial-sized (Earth-to-Neptune rad ii) extrasolar planets in the dwarf M-star eclipsing binary system CM Draconis. Preliminary photometric observational data of this system de monstrate that the observational noise is well characterized as white and Gaussian at the observational time steps required for precision ph otometric measurements. Depending on planet formation scenarios, terre strial-sized planets may form quite close to this low-luminosity syste m. We demonstrate, for example, that planets as small as 1.4 Earth rad ii with periods on the order of a few months in the CM Draconis system could be detected at the 99.9% confidence level in less than a year u sing l-m class telescopes from the ground. This result contradicts com monly held assumptions limiting present ground-based efforts to, at be st, detections of gas giant planets after several years of observation . This method can be readily extended to a number of other larger star systems with the utilization of larger telescopes and longer observin g times. Its extension to spacecraft observations should also allow th e determination of the presence of terrestrial-sized planets in nearly 100 other known eclipsing binary systems. (C) 1996 Academic Press, In c.