The dark, reddish object that rushed into our solar system in 2017 and was named after the Hawaiian word for messenger or scout has long puzzled scientists.
Among its peculiarities is the lack of gas and dust envelopes that comets generally give off as they warm up. Other expert work has suggested that the body is accelerated by the loss of water vapor and other gases – as seen with comets but not asteroids. The result is that “Oumuamua has been labeled” disguised comet “.
Scientists now say they’ve cleared up the mystery and tackled the countless pieces of the “Oumuamua” puzzle.
They say that “Oumuamua is an” active asteroid “formed from a body that has been torn apart by its parent star and then ejected into interstellar space.
“Most planetary bodies … are made up of many pieces of rock that have fused under the influence of gravity. You can imagine them as sand castles floating in space, “said Dr Yun Zhang, co-author of the new study by the Observatory of the Côte d’Azur in France.
These bodies are subject to a number of forces as they pass their star.
“A tidal encounter between a planet or a small body and a star is a tug of war game between the gravitational pull of the star and the self-gravity of the flying body,” said Zhang, noting that when the body passes too close to the star and enters the region of tidal disturbance, it can stretch and tear to give birth to fragments.
In the journal Nature Astronomy, Zhang and Professor Doug Lin of the Lick Observatory at the University of California, explain how they used computer models to reveal that such a process could have produced “Oumuamua and explain characteristics such as its movement of fall, its color and its unusual shape.
Zhang said that near and far parts of Oumuamua’s parent body would have been separated from each other in the tidal disturbance region, the ensuing elongated body was glued together by surface materials that melted close from the star and froze when the body flew. The result is that fragments formed from the body – such as “Oumuamua – would also have an elongated shape.
Zhang said that most of the volatiles on the surface of ‘Oumuamua would have been lost from heating by the star around which it formed, but some residual water ice could have been kept beneath its surface and then heated by our warmer sun – explaining its unusual acceleration. “We can call ‘Oumuamua an active asteroid,'” said Zhang.
The team says “Oumuamua could have formed from a comet or a planet many times the size of Earth, but the former better explains” the apparent groundwater ice of Oumuamua. The star around which “Oumuamua was formed, they add, would probably have been similar to our sun but smaller and denser – or perhaps a white dwarf.
Zhang says the results not only re-tap the much-publicized notion that “Oumuamua is an alien spacecraft, but offer an effective way to form asteroidal interstellar objects, previously considered rare.”
In addition, she says, with objects like “Oumuamua passing through” habitable zones “, like our own solar system, they can even carry seeds of life.
Arizona State University Dr. Alan Jackson, who was not involved in the study but who had previously researched “Oumuamua,” commended the work.
“The idea that” Oumuamua is a fragment of a larger body that was disturbed by the tide near its parent star was suggested by Matija Ćuk in 2018, “he said. “But this is the first work I have seen that really explores this idea in detail and shows that it could explain how” Oumuamua was produced and many of its unusual features. “