Oumuamua, the interstellar asteroid ( or is it ? )
Discovered by the Pan-Starrs telescope in October 2017, this rocky body has been claimed to be the first interstellar body to enter the solar system. It is interstellar in the sense it came from a different star system. This was determined by studying its orbit, and its chemical composition. It was found to have a higher velocity ( around 320,000 kilometres per hour ) than it would have if it orbited the Sun, hence it must have been from somewhere else.
( Of course, the below image is a piece of an artist’s imagination of how it would look like ).
The asteroid was also weirdly shaped like an elongated cigar, which drew media attention, who hypothesised that it could be an alien spaceship. After some debate, a paper was published in March 2018 which said that Oumuamua was in fact, a comet and not an interstellar asteroid as it was previously claimed.
This was established with some evidence relating to its trajectory through the Solar System. It was expected to go through a perfectly hyperbolic path due to the gravitation of the Sun, but it started deviating from the said path. This was reasoned by a phenomenon called outgassing.
https://www.youtube.com/watch?v=imKjVEVq_vs ( This video shows it better )
Outgassing, as the name suggests, refers to the release of gas which was trapped, dissolved or absorbed in the interior of some material. Since outgassing reduces the mass of the object in discussion, it is possible that it could have changed the trajectory of the body. This outgassing could have been caused by the heat of the Sun melting and evaporating the ice present in Oumuamua, leading to the conclusion that it may be a distant comet that wandered too close to the Sun.
Later this year, another study which believed that it was indeed interstellar narrowed down its source to 4 nearby stars by backtracking its trajectory. The scientists used ESA’s Gaia mission to determine how nearby stars’ gravity affected these rocky bodies. Two of them are HIP3757, a red giant star and HD292249, a Sun-like star. But it is still unsure how massive a planet/star would have been possible to eject a body with such high velocities.
Now, let us get to some facts.
Official designation : Originally C/2017 U1 ( thought to have a Coma) , then A/2017 U1 after discovering that it didn’t have a coma. Finally I/2017 U1 because it is believed to be Interstellar ( a first of its kind ).
Size: less than a kilometre long
Closest approach to Earth: 0.276 AU
Apparent Magnitude: >20 ( no wonder we couldn’t get a real image of it )
Trajectory: Hyperbolic
Composition: Metal-rich, organic compounds called tholins, maybe a bit of ice.
References :
Comments
Post a Comment