Best known for its magnificent system of rings, the enormous gas-giant Saturn is perhaps the most beautiful planet in our entire Solar System. Saturn’s mesmerizing, lovely, and enchanting ring system is a collection of a multitude of sparkling icy objects that range in size from smoke-size icy particles to large boulders about the same size as city skyscrapers rings. Even though the most famous planetary rings in our Solar System belong to Saturn, the other three giant denizens of the outer limits of our Sun’s family–Jupiter, Uranus, and Neptune–are also circled by lovely ring systems.
Astronomer Dr. Eric Mamajek of the University of Rochester in New York and his co-author Dr. Matthew Kenworthy of the Leiden Observatory in the Netherlands said that the ring system they have been observing–eclipsing the baby star J1407–is of enormous proportions. The ring system belonging to a companion of this distant young star was discovered in 2012 by Dr. Mamajek. The companion, which is likely a giant planet, is designated J1407b.
The new analysis of the data, led by Dr. Kenworthy, suggests that the ring system is made up of more than 30 rings, and each of them is tens of millions of kilometers in diameter. Furthermore, the astronomers detected gaps in the rings which suggest that exomoons may have formed. An exomoon is an alien moon that orbits an alien planet that is in orbit around an alien sun. The results of the new analysis will be published in The Astrophysical Journal.
A planetary ring is a disk composed of moonlets, dust, and an assortment of other small objects orbiting a planet or similar body. The composition of ring particles varies–they may be silicate or icy motes of dust. Larger rocks and boulders can also tumble around in the rings. Indeed, in 2007 tidal effects from eight moonlets only a few hundred meters across were spied within Saturn’s rings.
Shepherd moons are small moons that orbit near the outer edges of planetary rings or within ring gaps. The shepherd moons got their name because their gravity serves to maintain a sharply defined edge to the ring. Material that wanders too close to the shepherd moon’s orbit will either be tossed back into the body of the ring or unceremoniously hurled out of the system altogether. Sometimes this material may even be accreted onto the shepherd moon itself.
Several of the gas-giant planet Jupiter’s petite innermost moons–Metis and Andrastea–twirl around within Jupiter’s system of rings. It has been proposed that these rings–circling by far the largest planet in our Sun’s family–are made up of material that is being ripped off the two sister-moons by Jupiter’s tidal forces. This might be facilitated by the pelting impacts of ring material onto the moons’ surfaces.