Astronomers from Leiden Observatory, The Netherlands, and the University of Rochester, New York, just announced a rather extraordinary discovery.
A gigantic ring system recently eclipsed J1407, a 16-million-year old star about 430 light-years from Earth. Researchers say the mysterious system is probably made out of 37 rings that are much bigger than the ones of Saturn – roughly 200 times larger in fact – and the diameter is estimated to be nearly 56 million miles (90 million km).
“You could think of it as kind of a super Saturn,” says Eric Mamajek, co-author of the J1407 ring system analysis and professor of physics and astronomy at the University of Rochester.
To put this into perspective, “if we could replace Saturn’s rings with the rings around J1407, they would be easily visible at night and be many times larger than the full moon,” Matthew Kenworthy at Leiden Observatory explained to Phys.org.
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It was first discovered in 2007 when the SuperWASP observatory, which was built to discover “exoplanets” (planets outside our solar system), gathered data of an outer space body eclipsing the star J1407 and dimming its light with irregular frequency for a total of 56 days straight. Usually, when a planet passes in front of a star, scientists observe a reduction in starlight in that particular area for just a few hours. This was different.
“It took us a year even to convince ourselves of what we were seeing,” Mamajek explained.
“I took a printout of the light curve, put it on the wall, and stared at it for a week,” he told Time Magazine about noticing the irregular starlight interruption pattern. “It’s the same indirect way the rings of Uranus were discovered in 1977.”
“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,” Kenworthy added.
Even though no one has been able to find concrete evidence, the team of researchers believes that the newly discovered ring system is orbiting what could be a gas giant like and up to 40 times the size of Jupiter.
“The lack of a detection means it has to be substellar, and the only thing that could hold these rings in place is a planet,” Kenworthy proposed.
In addition to being the first ring system observed outside our solar system, this discovery might give astronomers a better insight into how moons around gas giants both outside and inside our solar system were formed.
“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,” says 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.”
This became clear to researchers at Leiden and Rochester after they discovered a gap in the ring system, which suggested that some of the disk material surrounding the planet had already formed one or more moons.
“In the case of J1407, we see the rings blocking as much as 95 percent of the light of this young Sun-like star for days, so there is a lot of material there that could then form satellites,” Mamajek concludes.
Because of this moon-building disk phenomenon, which can also be observed around Saturn today, the rings in the planet’s surrounding disk will most likely decrease in size over the next million years and ultimately disappear entirely after having formed satellite objects out of remaining “disk material.”
The current data is only based on one J1407 eclipse event back in 2007, which scientists believe won’t happen again until 5-7 years from now. Because they can’t keep their telescope pointed at the same object over such a long period of time, they are encouraging amateur astronomers at the American Association of Variable Star Observers to “catch” another passage of the ring system in front of the star to confirm that they are indeed looking at a gas giant planet at its core.
Kenworthy also explains that gathering eclipse data is the “only feasible way we have of observing the early conditions of satellite formation for the near future. J1407’s eclipses will allow us to study the physical and chemical properties of satellite-spawning circumplanetary disks.”