Saturday, October 01, 2016

Where Did Minor Planets Get Their Rings?

Where Did Minor Planets Get Their Rings?

ESO/L. Calçada/Nick Risinger (skysurvey.org)

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A study published in Astrophysical Journal Letters revealed how minor planets got their rings. The study explained that the rings were fragments produced when the minor planets came close to giant planets.

Previously, it was assumed that only giant planets like Saturn and Jupiter have rings but the 2014 discovery of centaur Chariklo disproved this. Centaurs are minor planets located between Jupiter and Neptune.

Another centaur called Chiron was then found to have the same rings. However, how the rings formed around the centaurs have remained a mystery until now.

Scientists from France and Japan created computer simulations that depicted centaurs moving close to giant planets. During such encounter, these centaurs usually get destroyed due to the giants’ tidal pull.

Of all 44, 000 centaurs around, 10 percent of them would come this close. However, other centaurs lucky enough to not experience the same fate only get partially destroyed, and the fragments from them eventually form the centaur’s ring.

Other factors also play a role in this ring formation. Experts suggest that the size of the centaur’s core, its distance of its closest approach to big planets, as well as its initial spin determine whether it will be annihilated completely or partially.

As of now, there have only been a few minor planets with rings found. However, the computer simulations created by the scientists demonstrate that such planets may be more common.

It is also possible that such centaurs with rings also have small moons but this requires further investigations.

Hyodo Ryuki of the Kobe University Department of Planetology, Graduate School of Science is the lead author for this study. His collaborators included Sébastien Charnoz of the Institute de Physique du Globe/Université Paris Diderot, Genda Hidenori of the Earth-Life Science Institute, Tokyo Institute of Technology and Ohtsuki Keiji of the Kobe University Department of Planetology, Graduate School of Science.