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J.M. Jenkins (SETI Institute/NASA Ames Research Center), W.J. Borucki (NASA Ames Research Center), J.L. Mena-Werth (University of Nebraska)
The proposed Kepler Mission seeks to apply transit photometry to determine the frequency, sizes, and orbital characteristics of terrestrial- sized (and larger) planets around a variety of stellar types. As Earth-sized transits of solar-like stars are small (~10 ppm), the issue of stellar variability (as well as instrumental precision) is important. Here we combine the results of the Active Cavity Radiometer for Irradiance Monitoring (ACRIM 1) aboard the Solar Maximum Mission (SMM) satellite along with recent measurements by the DIARAD/VIRGO instrument aboard SOHO to estimate the impact of stellar variability on the detectability of transits by Earth-sized planets of solar-like stars. The Power Spectral Densities (PSDs) that are derived from these are then fitted to a parametric model allowing us to examine stellar variability for stars with activity levels and rotation periods different from that of the sun. The resulting PSDs are then combined with shot noise and expected instrumental noise to assess the detectability of transits against the total expected noise. 100,000 stars will be surveyed for transiting planets with periods from a few days to two years. This establishes a minimum signal-to-noise ratio (SNR) for a single transit of ~3.5 \sigma for a planet exhibiting four transits to be detected 50% of the time, if the false alarm rate is set to be no more than one for the entire experiment. Monte Carlo simulations were performed to establish the receiver operating characteristics (ROC) curves for our detection algorithm. We present the results, which demonstrate that Kepler will be able to detect a large fraction of Earth-sized planets transiting solar-like stars in its field of view.
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The author(s) of this abstract have provided an email address for comments about the abstract: jjenkins@mail.arc.nasa.gov