- Astronomy: Telescopes in search of aliens
- Space.Borisov, the second interstellar comet to visit our solar system
- Oumuamua The first interstellar object we see is also the strangest
They are called Oumuamua and 2I / Borisov and are so far the only two interstellar visitors we have seen. When Oumuamua was observed in October 2017, its strange elongated shape and demeanor led to speculation that it might be an alien spacecraft. Comet 2I / Borisov was discovered on August 30 by amateur astronomer Gennady Borisov, making it the second space rock from another detected solar system. Now, in just one week, we receive two investigations that provide more data on the possible origin and composition of these enigmatic objects, but also new questions.
On the one hand, research in the journal Nature Astronomy ruled out last week that Oumuamua was a space vehicle and supported the theory, already defended in other studies, that its origin is natural. "Our scenario shows that all its strange characteristics can be explained based on well-known physical principles," Yun Zhang, the first author of the study on Oumuamua, who is currently about 2.6 billion kilometers from Earth's orbit, assures EL MUNDO. Its color and the absence of radio signals, he adds, also point to its natural origin.
The scientist believes that this object is a hybrid between a comet and an asteroid : "Like asteroids, it does not show traces of the coma [the cloud of dust and gas that surrounds a comet], but it does vaporize ice when it receives solar radiation, like a comet. So maybe we can call it an active asteroid, "says Zhang, a researcher at the National Astronomical Observatories of the Chinese Academy of Sciences.
According to his study, based on computer simulations, Oumuamua could come from a fragment that detached from another object when it passed very close to its star due to the influence of gravitational forces.
Zhang's study suggests that Oumuamua acquired its peculiar cigar shape when it left the solar system in which it originated. "Our scenario shows that it has held its shape very stably although elements such as hydrogen may have been added during its interstellar journey, which could have altered its shape but there is no evidence for this," he says.
Regarding the time you have been traveling, you will download two possibilities that are based on the measurement of your relative speed. "Either it comes from a young billion-year-old solar system, or it originated in an older system and has been traveling for billions of years. The second possibility is the most likely."
Carbon monoxide and hydrogen cyanide
On the other hand, the study focused on Comet 2I / Borisov published this Monday by the same magazine maintains that it probably formed in an extremely cold environment, since they have found large amounts of carbon monoxide in it.
It was last December 15 and 16 when the ALMA radio telescope, from the European Southern Observatory, pointed towards 2I / Borisov in what was the first direct observation of the chemical elements that exist in an object formed in a planetary system different from ours.
The observations, led by Martin Cordiner and Stefanie Milam of NASA's Goddard Space Center, showed that the gas coming from the comet contained unusual amounts of carbon monoxide (CO). According to his calculations, this number is between nine and 26 times higher than the average of a comet in the Solar System.
The main reason scientists are interested in studying comets is because these objects spend most of their lives far from any star. They remain in cold environments and, unlike planets, their internal composition has not changed significantly since they were born. Therefore, it is believed that they can offer information about the processes that took place during the birth of protoplanetary disks (clouds of gas and dust in which planets are born).
" It is the first time we have seen the inside of a comet from another solar system and it is dramatically different from most comets we have observed," said astrochemist Martin Cordiner.
Specifically, the ALMA radio telescope detected two molecules in the gas emitted by the comet: hydrogen cyanide (HCN) and carbon monoxide (CO). Scientists hoped to find hydrogen cyanide, and what they saw was a similar amount to that found in comets in our solar system, but finding so much carbon monoxide, they say, was a big surprise: "It must have formed from material very rich in monoxide. carbon, which is only found in regions of space with very low temperatures, below -250º Celsius, "says Stefanie Milam, a planetary scientist.
So, Cordiner adds, they believe Borisov could have formed in an extremely cold region of a distant planetary system. A region as cold as the distant Kuiper Belt, beyond Neptune, where a multitude of frozen bodies have been discovered.
Carbon monoxide is one of the molecules most frequently found in space and appears to be present in most comets, but in amounts that vary greatly. And scientists don't know why there is so much difference. It could influence where they formed or how close they are to the Sun, which would make their icy material evaporate more easily.
Scientists have no explanation for the unusual composition of 2I / Borisov, so this analysis has raised more questions than answers. Now they want to know if other interstellar comets have a similar composition or in the coming years objects with other peculiar chemical compositions will be found, and what implications this chemical cocktail has for understanding the formation of solar systems.
Since Borisov moves at a speed of 33 kilometers per second , they believe that he could have been traveling through interstellar space for billions of years.
Based on the results of his study, Yun Zhan believes that there is a large population of interstellar objects like Oumuamua although the chances of seeing them arise every one or two years: "Given how small they are and therefore difficult to discover, and the limited Telescopes that we have (it is difficult to cover the entire sky) are not always able to detect them when they visit us. "
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