Ploonets: When a moon escapes a planet’s orbit

Date:12 July 2019 Author: Sam Spiller Tags:, , , , , , , , , ,

Scientists have given a name to moons that move themselves out of their usual planetary orbit, and instead start orbiting nearby stars.

What do you get when a moon stops orbiting a planet and leaves to be its own? You get something called a ploonet.

Using modern-day telescopes, scientists are able to identify planetary objects that did not start out life on their own, but in fact were once tethered to another planet that eventually left it’s orbit. Here is where the new term ‘ploonet’ has originated.

Astrophysicist, Mario Sucerquia, leading fellow researchers at the University of Antioquia in Colombia, conducted a simulation to see if this would happen to moons that orbit a kind of planet called a ‘Hot Jupiter’. Hot Jupiters are giant planets primarily made up of gas that orbit very close to their sun. This results in their surfaces having scorchingly high temperatures. One of the closest Hot Jupiters to us is KELT 9b, which is about 650 light-years away and whose atmosphere has a temperature of around 4,300 degrees Celsius.

The simulation applies to Hot Jupiters as the researchers believe that these planets did not start out in life so close to a star. They slowly migrate towards it and in doing so, more and more energy is added into the orbit of any moons they have, which are then pushed away and flung completely free from them.

Some ploonets can be difficult to spot, as they may have the same characteristics as regular planets. Their life spans may also be shorter. Of the ploonets that the team simulated, half of them eventually crashed into their nearby star within half a million years. A number of the remaining ploonets then crashed within a million years.

This crashing, however, may help explain a series of other phenomena in space. Debris from them could result in planet’s having giant rings, or evaporating ice on the moon could give it a tail like a comet.

Planet Earth’s moon moves away from us by about four centimetres every year. It is possible that it will eventually turn into a ploonet, though scientists reckon that that would take around five billion years to happen.

With this new research at hand, astronomers may have an easier time identifying ploonets, which in turn could to lead to further insight on their origins.

Citation: arXiv:1906.11400 [astro-ph.EP]

Image: Pixabay

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