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Description
We present the results of a search for additional bodies in the GJ 1132 system through two methods: photometric transits and transit timing variations of GJ 1132b. We collected 21 transit observations of GJ 1132b with the MEarth-South array. We obtained 100 near-continuous hours of observations with the Spitzer Space Telescope, including two transits of GJ 1132b and spanning 60% of the orbital phase of the maximum (6.9-day) period at which bodies coplanar with GJ 1132b would transit. We exclude transits of additional Mars-sized bodies, such as a second planet or a moon, with a confidence of 99.7%. We find that the planet-to-star radius ratio inferred from the MEarth and Spitzer light curves are discrepant at the 3.7{sigma} level, which we ascribe to the effects of starspots and faculae. When we combine the mass estimate of the star (obtained from its parallax and apparent K_s_ band magnitude) with the stellar density inferred from our high-cadence Spitzer light curve (assuming zero eccentricity), we measure the stellar radius of GJ 1132 to be 0.2105_-0.0085_^+0.0102^ R_{sun}_, and we refine the radius measurement of GJ 1132b to 1.130+/-0.056 R_{Earth}_. Combined with HARPS RV measurements, we determine the density of GJ 1132b to be 6.2+/-2.0 g/cm^3^. We refine the ephemeris of the system (improving the period determination by an order of magnitude) and find no evidence for transit timing variations, which would be expected if there was a second planet near an orbital resonance with GJ 1132b.
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