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

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 clarity the formation and evolution of the PGC. Methods. Our backward and forward (±10000-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 ∼19 000 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.