More star info…

Thanks again for your amazing work and feedback.  We are working to keep up with you! There is now a data-download button (thanks to Chris, Arfon, Michael, and Stuart!) on the star pages. We are also integrating information about stars that are known eclipsing binaries (EB), Kepler planet candidates (PC) and false positives (FP). Here is an ascii list of light curves with this information. On this list, the APH number is given, followed by the Kepler ID and a flag (EB, PC, FP). For EB objects, D indicates detached binaries, SD is semi-detached, OC is an overcontact binary. Kepler PC stars include columns with the prospective period and planet radius (in Jupiter radii units).

One note about false positives: There are light curves that masquerade as transiting planets. For example, light from a bright foreground star is spread out over several pixels on the CCD detector.  The halo of starlight is swept up into a single brightness measurement by the Kepler team’s software. However, in some cases a more distant eclipsing binary (EB) star system blends into the edges of the foreground star.  Since the EB is more distant, it is fainter and contributes a smaller fraction of the light. In this case, the background eclipse produces a diluted signal that looks very much like a transiting planet.  There are a couple of ways to eliminate these imposters:

  1. the Kepler team has software that looks for pixel contamination and identifies the star as a false positive (FP). When available, we are listing this information on the light curve and star pages.

  2. Follow up radial velocity measurements of the bright star will also include the background blended eclipsing binary.  A large velocity signal can be a give away sign that the light curve does not arise from a transiting planet.

This follow-up is a critical effort, required to move an object from a transit candidate to a planet.

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