Scientists Shed New Light on Cigar-Shaped Interstellar Space Rock ‘Oumuamua’s Origins
In October 2017, astronomers spotted a strange, incredibly fast-moving object hurtling through the solar system. It was unlike anything that had ever been seen before.
‘Oumuamua—a Hawaiian term roughly translating to “scout” or a “messenger from afar”—is thought to measure around 800 by 100 feet and has a rare cigar-like shape. It is currently hurtling through the solar system at incredible speeds—around 16 miles per second—although it is tumbling rather than smoothly rotating.
Subsequent analysis showed that the object, ‘Oumuamua, was the first interstellar asteroid ever to visit our solar system. However, its origins remain a mystery.
Now, a new study—published in the journal Monthly Notices of the Royal Astronomical Society—has shed light on this issue. In the paper, Alan Jackson, from the Centre for Planetary Sciences at the University of Toronto Scarborough, and his colleagues propose that ‘Oumuamua very likely came from a binary star system in which two stars orbit a common center.
The scientists looked at how common binary star systems are in the Milky Way, and also how efficient they are at ejecting objects from their sphere of influence.
They found that binary star systems eject objects frequently. A sufficient number of binary systems exist to conclude that ‘Oumuamua was far more likely to come from such a system compared to a single star system like our own.
“It’s really odd that the first object we would see from outside our system would be an asteroid, because a comet would be a lot easier to spot and the Solar System ejects many more comets than asteroids,” Jackson said in a statement.
Researchers believe that ‘Oumuamua came from a system which contained a relatively hot, high mass star, because these tend to have more rocky objects orbiting them closely. It is also likely that the space rock was ejected from its home system around the time that planets were forming, the scientists propose in the study.
Because of its high speed and extremely eccentric orbit, scientists know it could not have originated in our solar system. At some point, it will eventually reenter interstellar space.
After its initial discovery, scientists assumed ‘Oumuamua was a comet—small icy bodies which warm and release gas in the form of a tail when they pass close to the Sun. However, it became clear as it passed close to the star that this was not the case, indicating that the object was, in fact, a rocky interstellar asteroid.
The latest findings have provided researchers with valuable insights into ‘Oumuamua’s history, however, with billions of star systems in the Milky Way, we are no closer to identifying exactly where it came from—and perhaps we never will.