‘Oumuamua (1I/2017 U1) is the first object of interstellar origin observed in the Solar system.
Recently, Micheli et al. (2018) reported that ‘Oumuamua showed deviations from a Keplerian orbit at a high statistical significance.

The observed trajectory is best explained by an excess radial acceleration ?a?r?2, where r is the distance of ‘Oumuamua from the Sun. Such an acceleration is naturally expected for comets, driven by the evaporating material. However, recent observational and theoretical studies imply that ‘Oumuamua is not an active comet. We explore the possibility that the excess acceleration results from Solar radiation pressure. The required mass-to-area ratio is m/A?0.1 g cm?2.

For a thin sheet, this requires a width of w?0.3?0.9 mm. We find that although extremely thin, such an object would survive an interstellar travel over Galactic distances of ?5 kpc , withstanding collisions with gas and dust-grains as well as stresses from rotation and tidal forces. We discuss the possible origins of such an object including the possibility that it might be a lightsail of artificial origin. Our general results apply to any light probes designed for interstellar travel.

Shmuel Bialy, Abraham Loeb
(Submitted on 26 Oct 2018 (v1), last revised 30 Oct 2018 (this version, v2))

Comments: 5 Pages, 1 Figure. Submitted to ApJL. Minor comments suggested by the referee were implemented
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:1810.11490 [astro-ph.EP] (or arXiv:1810.11490v2 [astro-ph.EP] for this version)
Submission history
From: Shmuel Bialy
[v1] Fri, 26 Oct 2018 18:33:15 UTC (107 KB)
[v2] Tue, 30 Oct 2018 22:54:48 UTC (108 KB)