2017MNRAS.467L..66D

The existence of significant anisotropies in the distributions of the directions of perihelia and orbital poles of the known extreme trans-Neptunian objects (ETNOs) has been used to claim that trans-Plutonian planets may exist. Among the known ETNOs, the pair (474640) 2004 VN₁₁₂-2013 RF₉₈ stands out. Their orbital poles and the directions of their perihelia and their velocities at perihelion/aphelion are separated by a few degrees, but orbital similarity does not necessarily imply common physical origin. In an attempt to unravel their physical nature, visible spectroscopy of both targets was obtained using the OSIRIS camera-spectrograph at the 10.4 m Gran Telescopio Canarias (GTC). From the spectral analysis, we find that 474640-2013 RF₉₈ have similar spectral slopes (12 versus 15 per cent/0.1 µm), very different from Sedna's but compatible with those of (148209) 2000 CR₁₀₅ and 2012 VP₁₁₃. These five ETNOs belong to the group of seven linked to the Planet Nine hypothesis. A dynamical pathway consistent with these findings is dissociation of a binary asteroid during a close encounter with a planet and we confirm its plausibility using N-body simulations. We thus conclude that both the dynamical and spectroscopic properties of 474640-2013 RF₉₈ favour a genetic link and their current orbits suggest that the pair was kicked by a perturber near aphelion.