Title: Fast Rotation of a Sub-km-sized Near-Earth Object 2011 XA3 Author: S. Urakawa, K. Ohtsuka, S. Abe, T. Ito, T. Nakamura
We present lightcurve observations and their multiband photometry for near-Earth object (NEO) 2011 XA3. The lightcurve has shown a periodicity of 0.0304 +- 0.0003 day (= 43.8 +- 0.4 min). The fast rotation shows that 2011 XA3 is in a state of tension (i.e. a monolithic asteroid) and cannot be held together by self-gravitation. Moreover, the multiband photometric analysis indicates that the taxonomic class of 2011 XA3 is S-complex, or V-type. Its estimated effective diameter is 225 +- 97 m (S-complex) and 166 +- 63 m (V-type), respectively. Therefore, 2011 XA3 is a candidate for the second-largest fast-rotating monolithic asteroid. Moreover, the orbital parameters of 2011 XA3 are apparently similar to those of NEO (3200) Phaethon but F/B-type. We computed the orbital evolutions of 2011 XA3 and Phaethon. However, the results of the computation and distinct taxonomy indicate that neither of the asteroids is of common origin.
The 240 - 530 metre wide asteroid 2011 XA3 will make a close pass (15.6 lunar distances, 0.0401 AU), travelling at 36.67 km/second, to the Earth-Moon system on the 22nd December, 2011 @ 19:55 UT ±00:01.
Orbital elements:
2011 XA3 PHA, Earth MOID = 0.0359 AU
Epoch 2012 Mar. 14.0 TT = JDT 2456000.5 MPC
M 25.89065 (2000.0) P Q
n 0.55177514 Peri. 323.77804 -0.46986158 +0.74800891
a 1.4721813 Node 273.60952 -0.65843248 -0.65065586
e 0.9268627 Incl. 28.01268 -0.58795984 +0.13088020
P 1.79 H 20.4 G 0.15 U 8