Welcome back to AITN Lite! It was hard to find a link to the last Astronomy in the News bulletin, so I have chosen the following story instead. This story is about a dwarf planet within our Solar System, Quaoar. The article can be found here:
Quaoar is a dwarf planet in the Kuiper Belt that is about half the size of Pluto. It has a moon, Weywot, which is thought to be a fragment of Quaoar that was ejected into orbit due to a collision event. However, the most striking feature of Quaoar is the recently discovered ring that surrounds the system. It is not unusual for planets or dwarf planets to have a ring, but this ring lies at a distance that is twice that should be capable of maintaining a stable ring.
The distance where the boundary between stable and unstable rings is called the Roche limit. Within this limit, the tidal forces from the central body will tear apart any object that attempts to form, causing a ring. Outside of this limit, the self-gravity of the objects in the ring will eventually allow coalescence and cause a moonlet.
As mentioned above, Quaoar shouldn’t have this ring as it should be coming together to form a moonlet, a process that is relatively quick on astronomical timescales, a matter of decades. The fact a ring exists, the authors of this study have postulated that the particles could be icy, which would cause elastic collisions, thus stopping the particles coming together to form the moonlet.
For further reading, a free version of the research article can be found here.