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Mexico City – Astronomers at the Harvard-Smithsonian Astrophysical Center believe that the elongated shape of the first known interstellar asteroid, "Oumuamua", functions as a sail that explains its unexpected acceleration.
They speculate on an artifical origin of the object, designed for the interstellar reconnaissance journey by an advanced civilization, but whose mission is over and has become a mess of a sinking.
The study, "Could solar radiation pressure explain the particular acceleration of Oumuamua?", Published in arXiv, was conducted by Shmuel Bialy, a postdoctoral researcher at the Institute of Physiology. theory and computer science, and Abraham Loeb, director of this center.
"Oumuamua" was first seen by the Pan-STARRS-1 poll 40 days after its closest passage to the sun (September 9, 2017). At this point, it was about 0.25 AU from the Sun (a quarter of the distance between the Earth and the Sun) and was already coming out of the solar system. At that time, astronomers noticed that it appeared to have a high density (indicating a rocky and metallic composition) and that it was spinning rapidly.
While he showed no signs of gas-free gas as he was passing near our Sun (which would indicate that it was a comet), a research team was able to obtain spectra indicating that "Oumuamua" was more cold than expected. Then, when he started leaving the solar system, the Hubble Space Telescope took some final images of "Oumuamua" that revealed unexpected behavior.
After reviewing the images, another international search team discovered that Oumuamua's speed had increased instead of slowing down as expected. According to them, the most likely explanation was that "Oumuamu" was releasing from the surface of the material because of solar heating (also called degassing). The release of this material, which corresponds to the behavior of a comet, would give "Oumuamua" the constant thrust it needed to reach that speed increase.
Bialy and Loeb propose a counter-explanation. If "Oumuamua" was really a comet, why did not he experience degassing when he was closer to our Sun? In addition, they cite other research that has shown that if degassing was responsible for acceleration, this would also have caused a rapid evolution of the "Oumuamua" bend (which was not observed) .
Bialy and Loeb are considering the possibility that "Oumuamua" is actually a light sail, a form of spacecraft that depends on the radiation pressure to generate propulsion, similar to that used in Breakthrough Starshot project sending small ships to d other systems.
Similar to what is planned for Starshot, this luminous candle can be sent by another civilization to study our solar system and look for signs of life. As Professor Loeb explained to Universe Today by email:
"We explain the excess of acceleration of" Oumuamua "away from the Sun due to the force that sunlight exerts on its surface.This force can explain the excess of acceleration measured, the object should be extremely small, in the order of a fraction of a millimeter thick but several tens of meters.This makes the object light for its surface and allows it to act as a light sail, its origin could be natural (in the interstellar medium or on protoplanetary disks) or artificial (like a probe sent for a reconnaissance mission in the inner region of the solar system). "
On this basis, Bialy and Loeb calculated the shape, thickness and surface / mass ratio of such an artificial object. They also tried to determine if this object could survive in interstellar space and whether or not it could withstand the tensile stresses caused by rotation and tidal forces.
With information from Europa Press
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