The mysterious object of the solar system called 'Oumuamua', discovered in 2017, still raises many questions from planetary scientists and astronomers. Where was it formed and where did it come from? The new study, published April 13 in Nature Astronomy, offers the first definitive answer to these questions.
Scientists led by Yuan Zhang of the National Astronomical Observatory of the Chinese Academy of Sciences have created a computer model that showed that objects like Oumuamua can be formed by tidal forces similar to those experienced by Earth's oceans. Their formation theory explains all of Oumuamua's atypical features.
According to Zhang, the object discovered on October 19, 2017 using the Panoramic Telescope and Rapid Response System 1 (Pan-STARRS1) in Hawaii is completely unlike anything else in the solar system. Its dry surface, unusual elongated shape and non-standard movement even made some scientists think that an alien probe has visited our system.
It is believed that when a smaller body passes very close to a much larger one, the tidal forces of the larger body can tear apart the smaller one, as happened with the comet Shoemaker-Levy 9 when it approached Jupiter. Tidal destruction processes can eject some particles into interstellar space. This is what was taken by scientists as the basis for the theory of the origin of Oumuamua. But whether such a process could explain Oumuamua's bizarre characteristics remained highly uncertain.
As a result, the research team conducted computer simulations to show the structural dynamics of an object flying close to a star. They found that if an object gets close enough to a star, the star can tear it apart into extremely elongated fragments, which are then ejected into interstellar space, which explains Oumuamua's shape.
The elongated shape is more convincing when we consider the change in the strength of a material during a star collision. The ratio of the long axis to the short axis may even be greater than ten to one, ”Zhang said.
At the same time, thermal modeling indicated that the surface of the fragments resulting from the destruction of the original body will melt at a very short distance from the star and condense at large distances. It is these processes that allow the formation of a cohesive crust, which will ensure the structural stability of an elongated shape.
Scientists managed to find out that heat dissipation during the destruction process under the influence of the ebb and flow of stars also consumes a large amount of volatiles, which not only explains the color of Oumuamua's surface, but also the dryness of its surface. However, some volatile substances with a high sublimation temperature hidden under the surface, such as water ice, can remain in condensed form.
