One of the most exciting recent space stories has been the discovery and study of ‘Oumuamua, a strange visitor from deep space named for the Hawaiian word for “scout” or “first visitor from afar.” The curious object was spotted in October 2017 by astronomer Rob Weryk of the University of Hawaii Institute for Astronomy, using the Pan-STARRS1 telescope and analysis of the asteroid (initially believed to be a comet) revealed that it originated from another solar system, making it the first known interstellar visitor to our own neck of the cosmic woods. The cylindrical shape, speed, and unusual trajectory of the object gave many astronomers and amateur skywatchers hope that we might have witnessed the first alien vessel or probe passing through our solar system. Further analysis, however, revealed it to be just another dumb space rock in a universe full of dumb space rocks.
Still, ‘Oumuamua proved to be a source of wonder and new data on these far-ranging interstellar objects. A recent study revealed that its unusual tumble suggests some kind of “violent” episode in its past, perhaps a collision with another object or body, but the origin of the strange interstellar visitor has remained a mystery – until now. A new study published by astronomers at the University of Toronto claims to have identified a possible origin for ‘Oumuamua, one that also might reveal just how differently planetary formation works in other solar systems.
According to the study, ‘Oumuamua likely came from a binary star system – a solar system with two suns. In single star systems like our own, most objects ejected into deep space are icy comets, since they form farther away from stars. In binary star systems, however, the heat of twin suns prevents these bodies from forming the icy shells which surround comets; thus, they are more likely to resemble the ‘dark’ rocky consistency of ‘Oumuamua and other asteroids:
Whereas in [our] Solar system the ejected material is overwhelmingly icy, we expect that around 36 percent of binaries may predominantly eject material that is rocky or substantially devolatilised, leading to similar expectations for the abundance of rocky/devolatilised bodies in the interstellar population.
While this study isn’t exactly an astronomical smoking gun which tells us exactly where this strange interstellar visitor came from, possibly narrowing the search to binary star systems could help narrow down the search to…well, uh, 80% of all known star systems. Oh. Get crackin’, astronomers.