Oumuamua: New study sheds light on the mysterious interstellar object

A new study reveals that the first known interstellar object to pass through our solar system is likely a piece of a Pluto-like planet from another solar system. Termed as ‘Oumuamua’, the object moves at over 26 km/s before and after picking up a boost from the Sun. The analysis may further help the scientists in learning about the stuff exoplanets are made of and the evolution of solar systems beyond our own. The term ‘Oumuamua’ is a Hawaiian name that means ‘scout’ or ‘messenger’. 

Steven Desch, an astrophysicist at Arizona State University and a co-author of the new study, in a press release said, “This research is exciting in that we’ve probably resolved the mystery of what ‘Oumuamua is and we can reasonably identify it as a chunk of an ‘exo-Pluto,’ a Pluto-like planet in another solar system”. He added, “Until now, we’ve had no way to know if other solar systems have Pluto-like planets, but now we have seen a chunk of one pass by Earth”. 

Mystery solved 

The makeup of the object remains unknown and the researchers have calculated what kinds of ice would sublimate at a rate that could lead to 'Oumuamua's rocket effect. It was concluded that the object is likely to be made of nitrogen ice, like the surface of Pluto and Neptune's moon Triton. Desch said, “In many ways 'Oumuamua' resembled a comet, but it was peculiar enough in several ways that mystery surrounded its nature, and speculation ran rampant about what it was”. The object is very much similar to a comet. 

(Illustration of a plausible history for ‘Oumuamua shows an origin in its parent system around 0.4 billion years ago; erosion by cosmic rays during its journey to the solar system; and passage through the solar system, including its closest approach to the Sun on 9 September 2017 and its discovery in October 2017. Image Credits: news.agu.org)

Desch and Jackson from Arizona State University determined that there are several characteristics of the object that differed from what would be expected from a comet. The object entered the solar system at a velocity that was lower than expected. Also, this indicates that the object had not been travelling in interstellar space for more than a billion years or so. Further, the object acquired a push away from the Sun. Jackson said, “We knew we had hit on the right idea when we completed the calculation for what albedo (how reflective the body is) would make the motion of ‘Oumuamua’ match the observations. That value came out as being the same as we observe on the surface of Pluto or Triton, bodies covered in nitrogen ice”. 

The researchers also calculated the rate at which the chunks of solid nitrogen ice would be knocked off the surfaces of Pluto. It was calculated that the probability that chunks of solid nitrogen ice from other solar systems would reach ours. The researchers also hope that the future telescopes, including those at the Vera Rubin Observatory/Large Synoptic Survey Telescope in Chile will be able to start finding even more interstellar objects.

(Image Credits: Unsplash/Bryan Goff)