Four years ago, astronomers detected ‘Oumuamua, the first known interstellar object to pass through our solar system. According to new research, the object had a number of strange and inexplicable features, some of which are consistent with an icy fragment ripped from a Pluto-like object.
“We suggest that‘ Oumuamua was probably launched from a young star system about half a million years ago, ’” the authors of two new research papers published in the Journal of Geophysical Research: Planets state. Because the object features features seen on the moon of Pluto and Neptune’s Triton, the authors, planetary scientist Alan Jackson and astrophysicist Steven Desch, both of Arizona State University, say that “‘Oumuamua may be the first piece of an exoplanet they bring us. “
Of course, what do they mean is that it is the first known piece of an exoplanet that brought us; and by exoplanet they mean an exo-dwarf planet, since Pluto is not technically a planet (if these corrections are not what they intended to say, then I’m saying they should be).
In their roles, Jackson and Desch classify ‘Oumuamua as an‘ ex-Pluto ’, which I think is pretty cool. In fact, astronomers often compare exoplanets and other astronomical phenomena to those orbiting our Sun, for example, referring to hot Jupiter, super-Earth, and sub-Neptune. We can now add “ex-Pluto” to the list of known astronomical objects and, by virtue of this, “Pluto” in general: small icy worlds located in the Kuiper belts (another analog term borrowed from our solar system) distant stars systems.
Until this traveler He paid us a visit from afar, “we haven’t had a way to know if other solar systems have planets similar to Pluto, but now we’ve seen a piece of one pass through Earth,” Desch said in an AGU statement. Well, that assumes that this interpretation is correct, that if so it means “Oumuamua would be” the first evidence that Pluto-like objects exist elsewhere in the galaxy.
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‘Oumuamua didn’t stay long when he visited our neighborhood in 2017, as he was traveling at speeds reaching 315,430 km / h (196,000 miles per hour). It’s hard to understand this kind of speed, but saying it’s traveled 54 miles every second (87 km / s) helps a bit.
The interstellar object was fast, but it was also strange. “Oumuamua is quite small, about half the size of a city block, though exceptionally thin, with a depth of about 35 meters. So strange and unprecedented is this form that at least one scientific he said, ‘Oumuamua may not be at all natural and instead some kind of probe sent by aliens. The object is also very bright (i.e. it has it a high albedo), has a faint comet coma and apparently has a slight acceleration speed not caused by gravity.
For first of the two studies, Jackson and Desch considered several different types of ice that could exist in this object. They did to determine how the evaporation of ice could contribute to the non-gravitational acceleration of the object. Scientists made calculations of how quickly these different ice creams were sublimated (when a (solid changes directly to gas) when ‘Oumuamua passed through our Sun. Factors such as mass, shape, and reflectivity were also taken into account to explain the propulsion effect produced by the sublimating gel.
Solid nitrogen turned out to be the best match. This is a very interesting result, as Pluto and Triton are known for their nitrogen-rich solid surfaces. and for albedos similar to that described by ‘Oumuamua.
Nitrogen could also explain the unusual shape of the object. According to the study, “Oumuamua had only taken on the appearance of a pancake, as a result of flying close to the Sun. The resulting fusion caused the object to lose more than 95% of its total mass and, as the ice evaporates, “the shape of the body would have been gradually flattened, as a bar of soap does when the outer layers are removed. through use, ”Jackson said.
A la second paper, the authors estimated the speed at which Pluto-like objects could have large chunks of ice ripped from their surfaces during their youth. They also estimated the speed at which these pieces would be interstellar and would make the long journey to our solar system.
“A similar fragment, generated in another solar system, after traveling for half a million years through interstellar space, would match the size, shape, brightness, and dynamics of [‘Oumuamua]”, The authors wrote in the second article.” The probabilities of detecting this object, as well as more comet objects such as the interstellar object 2I / Borisov, are consistent with the number of these objects we expect in space. interstellar if most stellar systems ejected comets and [nitrogen] fragments of ice with the same efficiency as our solar system ”.
The 2I / Borisov object, in case you were wondering, was detected in 2019 and is the second known interstellar object to pass through our solar system.
Matthew Knight, an astrophysicist at the United States Naval Academy and an expert on ‘Oumuamua, was impressed with the completeness of the two studies.
“The authors have done an excellent job of satisfying various observational and theoretical limitations with a simple, self-consistent model,” said Knight, who was not involved in the new research. in an email. “His key idea, that ‘Oumuamua was composed mainly of highly reflective nitrogen ice, is both creative and satisfactorily plausible, as we have ample evidence that nitrogen ice is common on the surface of Pluto and other large objects in the solar system. outdoor”.
Knight said these ideas have “a good chance of finally being accepted as the best explanation for ‘Oumuamua’.”
As it stands, we only know two interstellar objects, ‘Oumuamua’ and 2I / Borisov, but that could soon change thanks to the upcoming Vera C. Rubin Observatory and the ten-year survey of the legacy of space and time. project.
“LSST is expected to find about one per year, so when we have 10 or 20 known objects, we will be in a much better position to do a statistical evaluation, ”said Knight. “It will be very exciting to see how these results change our understanding of how our solar system works and reveal how similar our solar system is to other solar systems.”