The analysis and removal of systematic trends in stereo’s HI-1A photometry and a search for planetary transits

[摘要] STEREO’S imager, HI-1A, monitors nearly 500,000 stars down to 4th magnitude as it orbits the Sun. The resulting light curves offer unique characteristics and repeatability, which could make significant contributions to stellar variability surveys and the hunt for transiting planets.The HI-1A trend removal pipeline (TRP) was constructed to counteract systematic and observationsal effects and thereby increase the potential of a transit search. This pipeline uses a non-linear iterative filter to provide an adaptable noise-reduction process, without effecting transit-like signals. The TRP reduces the point-to-point scatter by up to 50 % for the brightest targets (R ≤ 6) and 25 % for the faintest (R ≥ 9).The correlated noise on transit timescales was found to be negligible for most targets and only 20 % of the total noise for the brightest stars, which amount to < 3 % of the sample. In an automated search for planet candidates, several transit signals were detected in the HI-1A light curves. Further testing suggests that none of these were veritable planet candidates. However the results show that Neptune-sized planets are certainly detectable and that a more effective reduction of solar-noise will lead to a successful planet search in the future.

[发布机构] University:University of Birmingham;Department:School of Physics and Astronomy

[关键词] Q Science;QB Astronomy