The new research results of the physical studies on the Near-Earth asteroid 2005 UD have been published in the Planetary and Space Science recently. This collaborated studies between Yunnan Observatories (HUANG jianing & WANG Xiaobin) and university of Helsinki (Muinonen Karri) provide the important evidences that the 2005 UD may come from the parent of Phaethon.
The Near-Earth asteroid 2005 UD, together with two other asteroids (3200) Phaethon and 1999 YC comprise of the Phaethon-Geminid stream Complex, briefly PGC. As Near-Earth asteroids, they pose a possibility to impact our planet for wandering the proximity of the Earth. Relatively, Phaethon has the most small MOID among the members of PGC, and has been identified as a PHA (Potential Hazard Asteroid).
Since 2016, the research group of small bodies of solar system in Yunnan observatoies, carried out photometric and spectroscopic observations for members of PGC with several facilities (2.4m and 0.45m telescopes at lijiang site, and 0.3m telescope at Ali site in Tibet). Based on photometric data, the shape, size, spin orientation and period, and surface scattering parameters of 2005UD are determined with a Markov Chain Monte Carlo method.
The three dimensions of 2005UD is 1.90×1.45×0.76 km, the orientation of its spin axis is located at the direction of (285.8o,-25.8o) in J2000 heliocentric ecliptic frame, and the rotation period is 5.2 hours.
If compared to the spin axis of Phaethon (311o.2,-23o.6) , the spin axis of 2005 UD is aligned with that of Phaethon, which implies that the 2005 UD probable is a fragment of the parent body of Phaethon.
Additionally, both photometric phase function parameters of 2005UD and Phaetho suggest a C-type of asteroid, which is another evidence that 2005 UD has a genetic relationship with Phathon.
This research program was funded by the National Natural Science Foundation of China and the Academy of Finland.
Contact:
WANG Xiaobin, Yunnan observatories, CAS
wangxb@ynao.ac.cn
