29 February 2000
Lincoln Near-Earth Asteroid Research
(66391) 1999 KW4, Solar System, (164121) 2003 YT1, (175706) 1996 FG3, 65803 Didymos
(185851) 2000 DP107 is a near-Earth asteroid that is notable because it provided evidence for binary asteroids in the near-Earth population.
The asteroid was discovered by the LINEAR program on February 29, 2000.
The binary nature of this asteroid was suggested from radar observations taken with the Goldstone radar antenna on September 22 and 23, 2000, based on an observing proposal by J.-L. Margot and observations by S. J. Ostro and colleagues. Confirming observations were obtained with the Arecibo telescope from September 30 to October 7, 2000.
The binary system
The 800-meter-diameter primary and the 300-meter-diameter secondary orbit each other with a separation of 2.6 kilometers and a period of 1.76 days.
The density of the primary was calculated using the orbital elements of the binary system, the primary-to-secondary mass ratio, and estimates of the primary size. The primary has a low density of 1.7 g/cm3, which may indicate a "rubble pile" structure containing rocks and voids.
The primary is spheroidal and is spinning at a rate near the breakup point for strengthless bodies. These two features were observed in multiple binary systems, suggesting that near-Earth asteroid binaries form by a mechanism involving spin-up and mass shedding. Currently the most generally accepted spin-up mechanism is the Yarkovsky–O'Keefe–Radzievskii–Paddack effect.