Four years ago, astronomers detected ‘Oumuamua’ – the first interstellar object we know to be moving through our solar system. According to new research, the object had a variety of strange and unexplained properties, some of which correspond to an icy shard torn from a Pluto-like object.
“We suggest that ‘Oumuamua was probably ejected from a young galaxy about half a billion years ago,'” say the authors of two new research articles published in the Journal of Geophysical Research: Planets, because the object displays features on Pluto and Neptune’s moon Triton, says the authors, planetary scientist Alan Jackson and astrophysicist Steven Desch, both of Arizona State University, “‘Oumuamua may be the first piece of an exoplanet brought to us.’
Of course, what they mean is that it is the first familiar piece of an exoplanet brought to us; and by exoplanet they mean an exo-dwarf planet, since Pluto is technically not a planet (if these corrections are not what they meant) to say, then I say that it must be).
In their papers, 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 with those in orbit around our sun, for example, referring to hot Jupiters, super-Earths and sub-Neptunes. We can now add ‘ex-Plutos’ to the list of known astronomical objects, and on this basis ‘Plutos’ in general – small icy worlds in the Kuiper belts (another similar term borrowed from our solar system) of distant stars systems.
To this traveler from afar we visit, ‘we had no way of knowing if other solar systems have Pluto-like planets, but now we have seen a part of the earth pass by,’ Desch said in an AGU. statement. Well, this is the assumption that this interpretation is correct, which means it would be ‘Oumuamua the first evidence that Pluto-like objects exist elsewhere in the galaxy.
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‘Oumuamua did not stay long when he visited our area in 2017, as it reached a speed of 315,430 km / h. It’s hard to comprehend that kind of speed, but it might help to say that it has traversed 54 km per second (87 km / s).
The interstellar object was fast, but it was also strange. ‘Oumuamua is quite small – about half the size of an urban block – but extraordinarily thin, with a depth of about 115 meters (35 meters). So strange and unprecedented is this form that at least one scientist said ‘Oumuamua may not be natural at all and instead a kind of sin sent by extraterrestrial people. The object is also very shiny (i.e. high albedo), it has a faint comet-like coma, and it shows a slight acceleration not caused by gravity.
For the first of the two studies, Jackson and Desch considered different types of ice that could exist on such an object. They did it to determine how the evaporation of ice can contribute to the observed non-gravity acceleration of the object. The scientists made calculations about how fast these different icebergs sublimated (when a solid turns directly into gas) when ‘Oumuamua passes by our sun. Factors such as mass, shape and reflection were also taken into account to explain the propellant-like effect produced by the sublimating ice.
Solid nitrogen was the best match. This is a very interesting result, because Pluto and Triton are known for their solid nitrogen-rich surfaces and for similar albedos as those described for ‘Oumuamua.
Nitrogen can also explain the unusual shape of the object. ‘Oumuamua has just donned his pancake-like appearance, a result of flying close to the sun, according to the study. The resulting melting resulted in the object losing more than 95% of its total mass, and as the ice evaporated, the shape of the body would gradually become more flat, just like a cookie soap when the outer layers were rubbed off. is used by, ”Jackson said.
In the second In the paper, the authors estimated the rate at which Pluto-like objects ripped large chunks of ice from their surfaces during their youth. They also estimated the rate at which these pieces would go interstellar and make the long journey to our solar system.
‘A similar fragment, generated in another solar system, traveled through interstellar space after about half a billion years, would correspond to the size, shape, brightness and dynamics of [‘Oumuamua], ”Wrote the authors in the second paper. ‘The chance of detecting such an object, as well as more comet-like objects such as the interstellar object 2I / Borisov, is consistent with the number of such objects we expect in interstellar space when most galaxies emit comets and [nitrogen] ice fragments with the same efficiency as our solar system. ”
Object 2I / Borisov, if you are wondering, was tracked down in 2019, and this is the second known interstellar object to go through our solar system.
Matthew Knight, an astrophysicist at the US Naval Academy and an expert on ‘Oumuamua’, was impressed with the comprehensiveness of the two studies.
“The authors have excelled in their task of meeting various observational and theoretical constraints with a simple and self-sustaining model,” said Knight, who was not involved in the new research. in an email. “The main idea, that ‘Oumuamua consists mainly of highly reflective nitrogen ice, is creative and satisfactory, as we have enough evidence that nitrogen ice is common on the surface of Pluto and other large objects in the outer solar system.’
Knight said these ideas ‘have a good chance of eventually being accepted as the best explanation for’ Oumuamua. ‘
As it stands now, we only know of two interstellar objects, ‘Oumuamua and 2I / Borisov, but that may soon change thanks to the upcoming Vera C. Rubin Observatory and the 10-year Legacy Survey of Space and Time. project.
‘LSST is expected to find about one per year, so if we have 10 or 20 objects, we will be in a much better position to make a statistical assessment, ”said Knight. “It will be very exciting to see how these results change our understanding of how our solar system works and how our solar system is similar to other solar systems, or not.”