The Albedo Distribution of Near Earth Asteroids
Abstract
The cryogenic Widefield Infrared Survey Explorer (WISE) mission in 2010 was extremely sensitive to asteroids and not biased against detecting dark objects. The albedos of 428 near Earth asteroids (NEAs) observed by WISE during its fully cryogenic mission can be fit quite well by a three parameter function that is the sum of two Rayleigh distributions. The Rayleigh distribution is zero for negative values, and follows f(x) =x\exp [{x}^{2}/(2{σ }^{2})]/{σ }^{2} for positive x. The peak value is at x = σ, so the position and width are tied together. The three parameters are the fraction of the objects in the dark population, the position of the dark peak, and the position of the brighter peak. We find that 25.3% of the NEAs observed by WISE are in a very dark population peaking at p _{ V } = 0.030, while the other 74.7% of the NEAs seen by WISE are in a moderately dark population peaking at p _{ V } = 0.168. A consequence of this bimodal distribution is that the congressional mandate to find 90% of all NEAs larger than 140 m diameter cannot be satisfied by surveying to H = 22 mag, since a 140 m diameter asteroid at the very dark peak has H = 23.7 mag, and more than 10% of NEAs are darker than p _{ V } = 0.03.
 Publication:

The Astronomical Journal
 Pub Date:
 October 2016
 DOI:
 10.3847/00046256/152/4/79
 arXiv:
 arXiv:1606.07421
 Bibcode:
 2016AJ....152...79W
 Keywords:

 minor planets;
 asteroids: general;
 Astrophysics  Earth and Planetary Astrophysics
 EPrint:
 7 pages LaTex, 4 figures, accepted for publication in the Astronomical Journal