Possible Detection of a Several Earth Mass Planet via Orbital Perturbations in the Gliese 436 System

J. L. Coughlin, G. S. Stringfellow, A. C. Becker, M. Lopez-Morales, F. Mezzalira, T. Krajci (NMSU, U. Colorado, U. Washington, Carnegie Institute, Astrokolkhoz Obs.)

We have collected new high-precision transit curves of Gl 436b with the 3.5-meter telescope at Apache Point Observatory, as well as other supporting telescopes. We model these along with all other published data, as well as a number of high-quality amateur observations, in a consistent and uniform manner. We find evidence for parameter variations in the transits of Gliese 436b, specifically rates of increasing inclination, width, and depth at 0.120 +/- 0.062 deg/yr, 3.43 +/- 1.01 min/yr, and 0.28 +/- 0.16 mmag/yr respectively. These variations are consistent with a second planet in the M-dwarf system with a mass of less than 12 Earth Masses. We do not detect any transit timing variations greater than ~1 minute, which constrains the second planet to a non-resonant orbit. If our trends are confirmed over the next year or two, it will be the first planet detected via orbital perturbations to a known transiting planet.