Super Saturn – How does a planet maintain rings 200 times larger than Saturn’s?

About 420 light years away in our galaxy lies a young planet going around a young Sun-like star. This planet has rings, much like Saturn. What is not like Saturn though is the truly colossal size of the rings.

Meet J1407b – an exoplanet 20 times more massive than Saturn. The rings of this Super Saturn span 180 million kilometers wide. That’s larger than the Earth-Sun distance of 150 million kilometers and 200 times bigger than Saturn’s rings! Make no mistake, J1407b is the true Lord of the Rings.

Artist’s impression of the massive ring system around J1407b. Credit: University of Rochester

Scientist could infer the presence of a large ring system because of the way it blocked light from the planet’s host star. Here is a video released by the discovery team showing the drop in the star’s brightness during what can be called a ring-eclipse.

Drop in the star’s brightness explained by the modeled rings of the planet J1407b. Credit: Matthew Kenworthy

The question is how are these huge rings not torn apart by the gravity of the planet’s host star?

Scientists ran computer simulations to model various ways in which rings of Super Saturn might go around it i.e in the same direction as the planet’s rotation (prograde) or the opposite direction (retrograde).

Scientists found that prograde rings didn’t survive a close, strong gravitational interaction with the host star. But in the case of retrograde rotation, the rings were intact! Having retrograde rotation means that the particles of the ring system are never too close to the star for too long, and thus can stay together. Here’s an animation showing the two scenarios.

A simulation of rings spinning in the opposite direction of the planet J1407b (left) vs. in the same direction (right). Credit: Steven Rieder

Even a retrograde ring system doesn’t last forever though. Scientists found that if the planet keeps orbiting the star, the rings will slowly disintegrate over a few thousand orbits.

Now the question is how likely is it for rings to form such that they spin in the opposite direction to the planet? That is being investigated.

There is another interesting thing about these rings. Did you notice the ring gap in the above video at 0:09?

Since the gap is quite substantial and the planetary system quite young, it is thought that the gap in the rings is caused by a newly formed moon. The rings of Super Saturn contain a lot of material in it, about the mass of Earth! This moon is thought to be 80% of that mass. That puts it as being larger than any Moon in the solar system. In fact, this exomoon, if confirmed, would be larger than Mars as well.

What we are seeing here are signs of a Jupiter/Saturn like elaborate system of moons being formed, albeit on a larger scale.

After the 13 years of stunning science of Saturn that NASA’s Cassini spacecraft gave us, one can only imagine the beautiful imagery and intricate data that will be revealed if we send a spacecraft to Super Saturn.

Dreamy. Just to think that there are such extreme worlds out there in the Universe waiting to be discovered, simply boggles my mind.

 Article published under the freedom-respecting Creative Commons Attribution-ShareAlike 4.0, minus any media file(s) credited independently.