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arXiv · 1808.07812

Unusual polarimetric properties of (101955) Bennu: similarities with F-class asteroids and cometary bodies

A. Cellino·S. Bagnulo·I. N. Belskaya·A. A. Christou
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Abstract

We have obtained polarimetric measurements of asteroid (101955) Bennu, a presumably primitive near-Earth object (NEO) that is the target of NASA's sample return mission OSIRIS-REx. During our observing campaign, Bennu was visible from Earth under a wide range of illumination conditions, with phase-angle in the range 16 to 57 degrees. Together with (3200) Phaethon and (152679) 1998 KU2, observed very recently, Bennu is the only existing example of a primitive NEO observed in polarimetric mode over a wide interval of phase angles. Based on our polarimetric data, we propose that Bennu belongs to the unusual F taxonomic class defined in the 80s. According to previous works, the F-class includes objects with cometary features. This fact can be of great importance for the interpretation of the results of the exploration of this object by OSIRIS-REx. From polarimetry we also derive an estimate of the geometric albedo of Bennu: 0.059 +/- 0.003.

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A. Cellino, S. Bagnulo, I. N. Belskaya, A. A. Christou. 2018-08-23. Unusual polarimetric properties of (101955) Bennu: similarities with F-class asteroids and cometary bodies. https://doi.org/10.1093/mnrasl%2Fsly156

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