Can planets exist in the habitable zone of 55 Cancri?

Abstract

Abstract The aim of our study is to explore the possible existence of Earth-mass planets in the habitable zone of 55 Cancri, an effort pursued based on detailed orbital stability simulations. This star is known to possess (at least) five planets with masses ranging between super-Earth and Jupiter-type. Additionally, according to observational constraints, there is a space without planets between ∼0.8 au and ∼5.7 au, and it is noted that the inner part of this gap largely coincides with 55 Cnc’s habitable zone—a sincere motivation for the search of potentially habitable planets. It has previously been argued that terrestrial habitable planets are able to exist in the 55 Cnc system, including a planet at ∼1.5 au. We explore this possibility through employing sets of orbital integrations and assuming an integration time of 50 Myr. We found that the possibility of Earth-mass planets in the system’s habitable zone strongly depends on the adopted system parameters, notably the eccentricity of 55 Cnc-f, which is controversial as both a high value (e ∼ 0.32) and a low value (e ∼ 0.08) have previously been deduced. In the case where the low value, the more plausible and most recent value, is adopted (together with other updates for the system parameters), Earth-mass planets would be able to exist in the gap between 1.0 au and 2.0 au, thus implying the possibility of habitable system planets. Thus, 55 Cnc should be considered a favorable target for future habitable planet search missions.