Children and adults alike marvel at the rings around Saturn. In a model of our solar system, Saturn — and its rings —is typically the one that gets the most attention. But while it is easy to be fascinated by Saturn, astronomers have recently found an exoplanet with an even grander expanse of wings that is sure to wow a new generation of stargazers.
Back in 2012, astronomers in the Netherlands discovered the first large ring system outside our solar system, circling either a giant planet or brown dwarf star called J1407b. A new analysis of that data finds that the ring system is actually massive — the more than 30 rings in the system are each tens of millions of kilometers in diameter and the system itself is much bigger and heavier than the famous rings circling Saturn, it’s so big that it eclipses the massive world’s host star!
“The details that we see in the light curve are incredible. The eclipse lasted for several weeks, but you see rapid changes on time scales of tens of minutes as a result of fine structures in the rings,” says Matthew Kenworthy ~ Leiden Observatory, one of the authors of the study.
“The star is much too far away to observe the rings directly, but we could make a detailed model based on the rapid brightness variations in the star light passing through the ring system. If we could replace Saturn’s rings with the rings around J1407b, they would be easily visible at night and be many times larger than the full moon.”
“This planet is much larger than Jupiter or Saturn, and its ring system is roughly 200 times larger than Saturn’s rings are today,” said co-author Mamajek, professor of physics and astronomy at the University of Rochester. “You could think of it as kind of a super Saturn.”
The ring system, 420 light years from Earth, likely contains roughly an Earth’s worth of mass in light-obscuring dust particles.
Professor Eric Mamajek puts into context how much material is contained in these disks and rings.
‘If you were to grind up the four large Galilean moons of Jupiter into dust and ice and spread out the material over their orbits in a ring around Jupiter, the ring would be so opaque to light that a distant observer that saw the ring pass in front of the sun would see a very deep, multi-day eclipse,’ he said.
These observations could be akin to a look back in time to see what Saturn and Jupiter were like as their own system of moons were first forming.
“The planetary science community has theorized for decades that planets like Jupiter and Saturn would have had, at an early stage, disks around them that then led to the formation of satellites,” according to Mamajek. “However, until we discovered this object in 2012, no one had seen such a ring system. This is the first snapshot of satellite formation on million-kilometer scales around a substellar object.”
Over time (we’re talking astrological time, so millions of years), the rings will probably thin out and disappear altogether, as the matter that makes them up clumps together and forms satellites.
The researchers encourage amateur astronomers to help monitor J1407, which would help detect the next eclipse of the rings, and constrain the period and mass of the ringed companion.
‘J1407’s eclipses will allow us to study the physical and chemical properties of satellite-spawning circumplanetary disks.’ Kenworthy said.
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