On the dynamical stability of the very low-mass object Gliese 22 Bb

► Accurate orbit and mass are given for the low-mass object Gl 22 Bb. ► Planetary or substellar nature is discussed. ► Prospects for the direct detection are discussed. ► Apsidal motion could be chaotic under certain conditions. ► Stability is assured for 10 Myr scale. Gliese 22 is a hierarchical triple red dwarf system formed by two close components, Aa and Ab, and a distant component, B, which is moving around the center of mass of the first two. The possible existence of a fourth very low-mass object (15 Jupiter mass) orbiting around component B was reported by Docobo et al. (Docobo, J.A. et al. [2007]. IAU Commun. 26, 3–4). In this probable scenario with four bodies, component B would be in reality two: star Ba and the new object, Bb. Two full three-dimensional accurate (circular and elliptical) solutions for the orbit of Bb have been obtained, along with an improved arrangement of the system masses. In addition, such a multiple system is analyzed by means of a (2 + 2)-body model considering its evolution during 10 Myr. In particular, we have studied its apsidal motion in order to eventually find any evidence of chaotic behavior. The nature of the new object as a giant planet or a brown star is also discussed.