Context. The close-in planet orbiting GJ 436 presents a puzzling orbital eccentricity (e ≃ 0.14) considering its very short orbital period. Given the age of the system, this planet should have been tidally circularized a long time ago. Many attempts to explain this were proposed in recent years, either involving abnormally weak tides, or the perturbing action of a distant companion.
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Beust et al. (2012) studied this question.