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

¹ INAF - Istituto di Astrofisica Spaziale (IASF), via del Fosso del Cavaliere, 00133 Rome, Italy e-mail: mariateresa.capria@iasf-roma.inaf.it
² INAF - Istituto per la Fisica del Plasma nello Spazio (IFSI), via del Fosso del Cavaliere, 00133 Rome, Italy
³ INAF - Osservatorio Astronomico di Capodimonte, via Moiariello 16, 80131 Napoli, Italy
⁴ Universitá Parthenope, Dip. Scienze applicate, Centro Direzionale Isola C4, 80143 Napoli, Italy

Received: 18 June 2007
Accepted: 18 May 2009

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 R_h of 5.54 AU, but it already displayed a well-developed 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.