The possible origin of three Apollo asteroids

3200 Phaethon, 2005UD, and 1999YC

¹ Astronomical Observatory, Volgina 7, 11060 Belgrade, Serbia
e-mail: nknezevic@aob.rs; ntodorovic@aob.rs
² Department of Astronomy, Faculty of Mathematics, University of Belgrade, Studentski trg 16, 11000 Belgrade, Serbia

Received: 9 May 2024
Accepted: 7 June 2024

Abstract

Aims. We study the possible dynamical background of three Apollo asteroids: 3200 Phaethon, 2005 UD, and 1999 YC. The source regions under consideration are the asteroid families (2) Pallas, in the outer belt, and two inner-belt families (329) Svea and (142) Polana. We also aim to explain some of the contradictions in the literature in regards to the origin of Phaethon.

Methods. Our methodology relies on the precise dynamical mapping of several mean motion resonances (MMRs), which are considered the main transport channels. This approach allows the clear detection of chaotic structures in an MMR and efficent selection of test asteroids for diffusion. We tracked the orbital evolution of the selected particles over 5 million years and registered all their eventual entries into the orbital neighborhood of the asteroids 3200 Phaethon, 2005 UD and 1999 YC. We performed massive calculations for different orbital and integration parameters using Orbit9 and Rebound software packages.

Results. We observed possible connections between three targeted Apollo asteroids and asteroid families we considered as their sources. The (2) Pallas family has the highest chance of being the origin of targeted asteroids, and (142) Polana has the lowest. The amount of transported material largely depends on the integrator, the integration step, and even the choice of the initial epoch, though to a lesser extent. There is a systematic discrepancy between the results obtained with Orbit9 and Rebound regarding the efficiency of the transport, but they show good agreement over delivery times and dynamical maps. A non-negligible number of objects approached all three target asteroids, which could indicate that the breakup of the precursor body occurred during its dynamical evolution.