1I/`Oumuamua as a Tidal Disruption Fragment From a Binary Star System

TL;DR

`Oumuamua is likely a fragment from a tidally disrupted planet ejected by a dense binary star system, explaining its unusual shape, lack of activity, and interstellar trajectory.

Contribution

This paper proposes a novel origin for `Oumuamua as a tidally disrupted planetary fragment from a binary system, contrasting with previous cometary or asteroid hypotheses.

Findings

`Oumuamua's characteristics are inconsistent with typical cometary activity.

Binary star systems are more efficient at ejecting small planetary fragments than single stars.

Tidal disruption by dense stars like red dwarfs can produce 100-m fragments ejected into interstellar space.

Abstract

1I/`Oumuamua is the first known interstellar small body, probably being only about 100~m in size. Against expectations based on comets, `Oumuamua does not show any activity and has a very elongated figure, and also exhibits undamped rotational tumbling. In contrast, `Oumuamua's trajectory indicates that it was moving with the local stars, as expected from a low-velocity ejection from a relatively nearby system. Here I assume that `Oumuamua is typical of 100-m interstellar objects, and speculate on its origins. I find that giant planets are relatively inefficient at ejecting small bodies from inner solar systems of main-sequence stars, and that binary systems offer a much better opportunity for ejections of non-volatile bodies. I also conclude that `Oumuamua is not a member of a collisional population, which could explain its dramatic difference from small asteroids. I observe that 100-m small bodies are expected to carry little mass in realistic collisional populations, and that occasional events when whole planets are disrupted in catastrophic encounters may dominate interstellar population of 100-m fragments. Unlike the Sun or Jupiter, red dwarf stars are very dense and are capable of thoroughly tidally disrupting terrestrial planets. I conclude that the origin of `Oumuamua as a fragment from a planet that was tidally disrupted and then ejected by a dense member of a binary system could explain its peculiarities.