Harvard-Smithsonian astronomers: could the mysterious interstellar object be part of an ET probe?

First discovered a year ago, Oumuamua is the strange cigar-shaped object of interstellar origin that flew through our solar system at 196,000 mph. Since it was first spotted, scientists haven't decisively determined whether it's a mildly active comet or something else. Now, astronomers Shmuel Bialy and Abraham Loeb of the Harvard Smithsonian Center for Astrophysics have released a scientific paper asking if Oumuamua could be a "lightsail of artificial origin," part of a space probe developed by an advanced extraterrestrial civilization. Of course this is not a statement of fact but rather a question, albeit a very very interesting one. From CNN:

"'Oumuamua may be a fully operational probe sent intentionally to Earth vicinity by an alien civilization," they wrote in the paper, which has been submitted to the Astrophysical Journal Letters.

IThe theory is based on the object's "excess acceleration," or its unexpected boost in speed as it traveled through and ultimately out of our solar system in January 2018.

"Considering an artificial origin, one possibility is that 'Oumuamua is a light sail, floating in interstellar space as a debris from an advanced technological equipment," wrote the paper's authors, suggesting that the object could be propelled by solar radiation.

"COULD SOLAR RADIATION PRESSURE EXPLAIN 'OUMUAMUA'S PECULIAR ACCELERATION?" (PDF)

(image: artist's impression of Oumuamua, ESO/M. Kornmesser)