A&A 450, L25-L28 (2006)
DOI: 10.1051/0004-6361:200600022

Letter

Apollo asteroid 2005 UD: split nucleus of (3200) Phaethon?

K. Ohtsuka¹, T. Sekiguchi², D. Kinoshita³, J.-I. Watanabe², T. Ito², H. Arakida² and T. Kasuga<sup>4

1</sup>  Tokyo Meteor Network, Daisawa 1-27-5, Setagaya-ku, Tokyo 155-0032, Japan
    e-mail: ohtsuka@jb3.so-net.ne.jp
²  National Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka, Tokyo 181-8588, Japan
³  Institute of Astronomy, National Central University, 300 Jhongda Rd, Jhongli, Taoyuan 32001, Taiwan
⁴  The Graduate University for Advanced Studies, Osawa 2-21-1, Mitaka, Tokyo 181-8588, Japan

(Received 14 December 2005 / Accepted 7 March 2006 )

Abstract
Context.The recently discovered Apollo asteroid 2005 UD is the most likely candidate for being a large member of the Phaethon-Geminid stream Complex (PGC).
Aims.Detecting more complex members like this should clarify the formation and evolution of the PGC.
Methods.Our backward and forward (-yr) integration of the Kustaanheimo-Stiefel regularized equation of motion revealed that the orbital evolutions of Apollo asteroids (3200) Phaethon and 2005 UD show a similar profile, time-shifting by ~4600 yr.
Results. Within the PGC, this time shift is rather large against the time-lag of 220 yr for Phaethon-Geminids and ~3900 yr between Phaethon-Sextantids, although much smaller than that of ~ yr between Phaethon-Canis Minorids.
Conclusions.This is a km-order object, hence may be a split nucleus of Phaethon. Besides, the orbital parameters of 2005 UD and the Sextantids are in good agreement along with the time-lag of 100 yr. Therefore, the Sextantid meteor shower seems to be associated more closely with 2005 UD than Phaethon.

Key words: minor planets, asteroids -- methods: numerical -- meteors, meteoroids

© ESO 2006

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