Planet J1407b has Rings 200 Times Larger than Saturn
J1407b, affectionately dubbed ‘Super-Saturn’, is a young exoplanet that orbits a sun-like star, J1407. It is a world that remains shrouded in mystery, primarily known for its extraordinary ring system.
Discovered by astronomers using data from the SuperWASP project, this planet’s rings are not just a little larger than those we are familiar with; they are over 200 times the size of Saturn’s.
The rings of J1407b are not only vast but complex, comprising approximately 37 individual rings, each spanning tens of millions of kilometers in diameter.
These colossal rings cast a shadow so expansive that they eclipsed their host star for several weeks, a phenomenon observed in early 2007. The sheer scale of this ring system suggests the presence of gaps within, possibly carved out by ‘exomoons’, hinting at a dynamic and evolving system.
To put this ring system into perspective, if Saturn possessed the same rings, they would be several times greater in diameter than the moon in the night sky. It would not only be visible with the naked eye, but it would completely dominate the view.
“It’d be huge. You’d see the rings and the gaps in the rings quite easily from Earth,” said Matthew Kenworthy of the Leiden Observatory in the Netherlands, one of the co-authors on the paper describing the findings, at the time. “It’d be several times the size of the full moon.”
Exoplanet J1407b was discovered in 2012 by astronomer Eric Mamajek, who was analysing data from the SuperWASP (Super Wide Angle Survey for Planets) project, which used the transit method to identify exoplanet candidates.
When an exoplanet passes in front of its host star it blocks some of the light coming from the star. Usually the effect is tiny: even a planet the size of Jupiter may block just 1% of the star’s light.
This is what makes J1407b out of the ordinary. It blocked 95% of the light from the star.
Studying the data from SuperWASP, Mamajek saw that J1407 was a young star, approximately 16 million years old, as its rotation was just 3.2 days (our, older, sun takes 25 days to complete one rotation).
Then, for two months in 2007, it did something very strange. The star very quickly faded, then brightened again, then faded away for a week before reversing the pattern.
In just one night during this period, the light from the star dropped by half! The only rational explanation was that a complex and very large ring system was passing between the star and the SuperWASP telescopes on Earth.
The rapid fading and dimming of the star gave the speed and size of the rings. Rapid changes in the light curve, lasting just tens of minutes, revealed the fine structures within the ring system.
J1407b is the first exoplanet with a ring system to be discovered. Its orbital period is around ten years.
The rings are as large as the orbit of Venus around our Sun and are very complex. They contain about one Earth mass of material and cover over 40,000 times the area of Saturn’s rings.
