New Observations and a Possible Detection of Parameter Variations in the Transits of Gliese 436b

TL;DR

This paper reports new ground-based observations of Gliese 436b, analyzes all available transit data, and suggests possible orbital inclination variations indicating perturbations by a small unseen planet.

Contribution

It provides the first transit observation from 2005 and suggests potential orbital inclination changes caused by an additional planet.

Findings

No significant transit timing variations detected.

Possible evidence for increasing orbital inclination.

Supports presence of a <12 Earth mass perturbing planet.

Abstract

We present ground-based observations of the transiting Neptune-mass planet Gl 436b obtained with the 3.5-meter telescope at Apache Point Observatory and other supporting telescopes. Included in this is an observed transit in early 2005, over two years before the earliest reported transit detection. We have compiled all available transit data to date and perform a uniform modeling using the JKTEBOP code. We do not detect any transit timing variations of amplitude greater than ~1 minute over the ~3.3 year baseline. We do however find possible evidence for a self-consistent trend of increasing orbital inclination, transit width, and transit depth, which supports the supposition that Gl 436b is being perturbed by another planet of < 12 Earth Masses in a non-resonant orbit.