Letter to the Editor

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

¹ 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.