Interstellar Interloper 1I/2017 U1: Observations from the NOT and WIYN Telescopes
David Jewitt, Jane Luu, Jayadev Rajagopal, Ralf Kotulla, Susan, Ridgway, Wilson Liu, and Thomas Augusteijn

TL;DR
This paper reports detailed observations of 'Oumuamua, the first known interstellar object passing through our solar system, revealing its physical properties, composition, and possible origin, and estimating the population of similar objects.
Contribution
It provides the first comprehensive physical characterization of 'Oumuamua, including its shape, rotation, and surface properties, and estimates the interstellar population of similar objects.
Findings
'Oumuamua has an elongated shape with a 6:1 axis ratio.
It shows no signs of cometary activity or exposed ice.
The population of similar interstellar objects inside Neptune's orbit is estimated at around 10,000.
Abstract
We present observations of the interstellar interloper 1I/2017 U1 ('Oumuamua) taken during its 2017 October flyby of Earth. The optical colors B-V = 0.700.06, V-R = 0.450.05, overlap those of the D-type Jovian Trojan asteroids and are incompatible with the ultrared objects which are abundant in the Kuiper belt. With a mean absolute magnitude = 22.95 and assuming a geometric albedo = 0.1, we find an average radius of 55 m. No coma is apparent; we deduce a limit to the dust mass production rate of only 210 kg s, ruling out the existence of exposed ice covering more than a few m of the surface. Volatiles in this body, if they exist, must lie beneath an involatile surface mantle 0.5 m thick, perhaps a product of prolonged cosmic ray processing in the interstellar medium. The lightcurve range is unusually large at…
Peer Reviews
No public reviews on file for this paper yet. If you reviewed it on a platform where reviews are public (OpenReview, ICLR, NeurIPS, ICML), you can paste yours below so the community can read it here.
Videos
No videos yet. Explain this paper in a talk, walkthrough, or lecture? Add one.
