Thermal modeling of the active Centaur P/2004 A1 (LONEOS)

Abstract

Context. The Centaurs are a dynamical class of minor bodies in the Solar System, moving on chaotic orbits with perihelion lying between Jupiter and Neptune orbits. P/2004 A1 (LONEOS) is a recently discovered object belonging to this class, observed at the TNG telescope in La Palma (Canary Islands) when it was at the heliocentric distance Rh of 5.54 AU, but it already displayed a welldeveloped coma and a long, sharp tail-like structure. Aims. We want to investigate whether it is possible to explain the strong activity of this body in terms of the usual sublimation mechanisms. Methods. We simulated the thermal evolution of LONEOS using a nucleus thermal evolution and differentiation model and took into account that it is being injected for the first time on an inner orbit as a consequence of a close encounter with Saturn experienced in 1992. Results. We show that, considering its peculiar dynamical history, it is possible to explain the activity of this Centaur with the sublimation of very volatile ices.