Its name means ‘visitor from afar’, since it is the first interstellar object (that we have detected) to visit our solar system. Given its exotic nature, the origin of Oumuamua has become a source of speculation since its discovery by a Hawaiian telescope in October 2017.
This interstellar object has the elongated shape of a large ‘cosmic cigarette’ 400 meters long and shows a chaotic rotation, which puzzles scientists. Given its rapid movement (at 95,000 kilometers per hour), we know that it is impossible for it to have formed in our solar system. The fact that it does not have a tail, like other asteroids, also misleads experts. Deep red in color and very dense, probably because it contains a lot of metal, Omuamua is nothing like any known object.
Although the hypothesis most supported by scientists is that it is nothing more than a peculiar interstellar asteroid, some others, such as certain members of the Harvard-Smithsonian Center for Astrophysics, proposed that it is actually a light probe of a civilization alien. But there is no detectable electromagnetic radiation or any other evidence to show that this not without controversy conclusion is anything more than mere (and sensational) intuition.
Now, a new study published April 13 in Nature Astronomy offers one of the first comprehensive answers to the questions of how Oumuamua formed and where it came from.
The research consisted of computer simulations to show how objects like Oumuamua can form under the influence of tidal forces similar to those of Earth’s oceans, but in this case stellar. This formation hypothesis, according to the study authors, would explain all the unusual characteristics of Oumuamua.
To understand it, one must start from the hypothesis that Oumuamua had a solar system of origin: “Oumuamua-like interstellar objects can form through extensive fragmentation during close encounters with their host stars, and then are expelled into space. interstellar, ”the document cites.
Fragmentation caused by a ‘stellar tide’
When a smaller body passes very close to a much larger one, tidal forces from the larger body can break apart the smaller one, as happened with Comet Shoemaker-Levy 9 when it approached Jupiter. According to computer simulations, if an object gets close enough to its star, it can break it into extremely elongated fragments “in a long-axis to short-axis ratio that can be even greater than ten to one,” as the document cites; and then it would be ejected into interstellar space. This process, which they have called stellar tide, is what has been suggested as a possible origin for Oumuamua.
Moreover, to the disappointment of some, again, the researchers insist: “The absence of radio emissions suggests that Oumuamua is a natural object.”
In addition, the researchers have applied thermal modeling of the surface of Oumuamua, which is also consistent with their fracture hypothesis: the initial fragments would melt at a very short distance from the star and recondense at greater distances, thus forming a cohesive crust that would guarantee the structural stability of the elongated shape.
A Family of Objects as Oumuamua
Moreover, the researchers have also calculated that there must be an extremely large population of interstellar objects like Oumuamua, and that this is just the tip of the iceberg. “The Oumuamua discovery implies that the population of rocky interstellar objects is much larger than we previously thought. On average, we believe that each planetary system should eject about 100 billion objects like Oumuamua .”
The researchers’ calculations demonstrate the efficiency of stellar tidal forces in producing such objects. This also implies that other objects, such as long-lived comets, debris discs, and even super-earths could transform into Oumuamua-shaped pieces during their stellar encounters.
Oumuamua has allowed astrophysicists and astrobiologists to open up very novel fields of work: given that these objects can cross the domains of habitable zones (as has happened in our case), the possibility that they can transport matter capable of generating life cannot be ruled out (the panspermia theory). Additionally, these interstellar objects could provide clues to how planetary systems form and evolve.
Referencia:
¡Tidal fragmentation as the origin of 1I/2017 U1 (‘Oumuamua)’, Nature Astronomy (2020). DOI: 10.1038/s41550-020-1065-8
