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Scientists Track Down Origins Of The Mysterious Alien Object 'Oumuamua

Jan 18, 2019 11:38 AM EST
An artist’s impression of the first interstellar visitor `Oumuamua, which was discovered on Oct. 19, 2017 by the Pan-STARRS 1 telescope in Hawaii. A new study traces back its flight to find out where it came from.
(Photo : ESO | M. Kornmesser)

The elusive 'Oumuamua is the first ever known interstellar visitor to grace the solar system's skies, but much about it remains a mystery.

Probably the most pressing question is: where did it come from? Since it hurtled through the solar system in 2017, scientists have wondered about 'Oumuamua's origins.

Now, a team from the Max Planck Institute for Astronomy have narrowed down its source to four possible stars.

'Oumuamua, The First Ever Interstellar Visitor

'Oumuamua stunned astronomers when it was initially detected. After all, it's the first time in history that a visitor from another star system has been observed in the solar system.

At the time, no one could definitively explain what 'Oumuamua is exactly or where it came from. Is it a comet? An asteroid? It could be another type of cosmic rock entirely, but the answer was elusive as the mysterious object soon disappeared out of sight of astronomers.

After poring over the data that 'Oumuamua left in its wake, a study published in 2018 declared that despite the notable absence of a tail, the solar system's first interstellar visitor is most likely a comet.

The answer to the next question — where it came from — now comes in a new study published online.

Tracing 'Oumuamua's Origins

In the paper, which has also been accepted for publication in the Astrophysical Journal, researchers analyzed data from the ESA astrometry satellite Gaia to identify four stars where 'Oumuamua could have begun its flight over a million years ago. To do this, the team led by Coryn Bailer-Jones of the Max Planck Institute for Astronomy tracked the rock's flight backward.

One of the keys to their research is taking into account the findings of the June 2018 study, particularly the slight change and acceleration in 'Oumuamua's orbit as it approached the sun, according to Phys Org. The notable change is likely due to outgassing, a known phenomenon of comets when sunlight melts the ice at the rock's core and produces gas that accelerates its flight.

As Bailer-Jones and her team were able to include this adjustment in their study, they achieved a more precise map of 'Oumuamua's journey. The researchers also took into account the gravitational influence of other stars the rock may have passed during its long and lonely journey through the cosmos.

Four Likely Candidates

From findings of the current study and previous ones, the scientists know that tracing back 'Oumuamua's path would likely lead to the rock's home star. It's also generally accepted that this star would probably be relatively slow, since the rock would not be ejected at high speeds.

Four stars came close to the researchers' properties of where the mysterious rock might have come from: reddish dwarf star HIP 3757, the sun-like HD 292249, and two other little-known stars.

However, a giant planet would have to be present in these star systems to be able to eject 'Oumuamua at its speed. No such planets have been observed in the four candidate stars yet, although this could change when scientists take a closer look.

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