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Title: THE POSSIBLE MOON OF KEPLER-90g IS A FALSE POSITIVE

The discovery of an exomoon would provide deep insights into planet formation and the habitability of planetary systems, with transiting examples being particularly sought after. Of the hundreds of Kepler planets now discovered, the seven-planet system Kepler-90 is unusual for exhibiting an unidentified transit-like signal in close proximity to one of the transits of the long-period gas-giant Kepler-90g, as noted by Cabrera et al. As part of the ''Hunt for Exomoons with Kepler'' project, we investigate this possible exomoon signal and find it passes all conventional photometric, dynamical, and centroid diagnostic tests. However, pixel-level light curves indicate that the moon-like signal occurs on nearly all of the target's pixels, which we confirm using a novel way of examining pixel-level data which we dub the ''transit centroid''. This test reveals that the possible exomoon to Kepler-90g is likely a false positive, perhaps due to a cosmic ray induced sudden pixel sensitivity dropout. This work highlights the extreme care required for seeking non-periodic low-amplitude transit signals, such as exomoons.
Authors:
; ;  [1] ; ;  [2] ;  [3] ;
  1. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)
  2. Department of Astrophysical Sciences, Princeton University, Princeton, NJ 05844 (United States)
  3. Department of Space Studies, Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, CO 80302 (United States)
Publication Date:
OSTI Identifier:
22364420
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 799; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COSMIC RADIATION; DIAGRAMS; MOON; PERIODICITY; PHOTOMETRY; PLANETS; SENSITIVITY; SIGNALS; STAR EVOLUTION; STARS; VISIBLE RADIATION