Artist’s conception of the extrasolar ring system circling the young giant planet or brown dwarf J1407b. (Ron Miller)
One of our solar system’s most fascinating planets is Saturn. It’s the 2nd largest planet, after Jupiter. But what makes Saturn stand out from the others is the dazzling system of rings that surround it.
Recently, a Dutch and an American astronomer found that an extrasolar object, discovered back in 2012, is surrounded by a ring system that’s 120 million kilometers in diameter, which is more than two hundred times as large as the rings circle Saturn.
The astronomers are still trying to determine whether the object, dubbed J1407b, is a large Jupiter-like planet or a brown dwarf, which is a celestial body that began forming as a star, but wasn’t able to sustain the needed hydrogen-1 fusion to make it a main sequence star.
The ring system surrounding J1407b, the first of its kind to be found outside our solar system, contains of over 30 rings, with each of them tens of millions of kilometers in diameter. The astronomers believe that the material in the ring system probably contains about an Earth’s worth of mass.
The “exo-object” orbits a very young – only about 15 million years old – Sun-like star called J1407 some 400 light years away.
Back in 2012 a team led by Dr. Eric Mamajek, an astronomer from New York’s University Of Rochester, studied a number of sun-like stars a few hundred light-years away from data gathered in 2007 by the UK’s SuperWASP (Wide Angle Search for Planets) extra-solar detection program. By chance they happened to notice that one of the stars flickered on and off over a two month period.
The rings around J1407b are so large that if they were put around Saturn, we could see the rings at dusk with our own eyes and camera phones. Here the rings as they would be seen in the skies of Leiden, above the Old Observatory and the Academic Building. (M. Kenworthy/Leiden)
The unusual changes in the brightness of the star – “flickering” – prompted Mamajek and his team to consider a number of different ideas of just what could be causing the variations. But in the end, the only model that made sense was one that had a giant planet-like object with a huge array of rings around it.
Mamajek joined his colleague Matthew Kenworthy from the Netherland’s Leiden Observatory to reanalyze their data in 2014.
This new analysis, according to Mamajek, provided the researchers with greater detail to better study the structure of the rings around J1407b.
For the 2012 study the researchers produced a model that included four rings. But that model, while close, didn’t quite completely fit all of their data. A newer model crafted from the reanalyzed data features over 30 rings.
The new model also shows very clean gaps with very abrupt changes within the density of the rings.
Similar gaps found in Saturn’s ring system indicate the presence of a moon. Mamajek explained that either there’s a moon actually carving out the gap or the gravitational effect of a moon further out or in that’s creating the interruption in the rings.
“The gaps we see are very clean, so there must be something in there that’s gobbling up all the material or dynamically throwing it out of the system,” said Mamajek.
The ring system itself may actually be a protoexosatellite disk or circumplanetary disk, according to the researchers.
“I think what we’re seeing here is the stage where moons are actually forming,” said Mamajek.
Video showing a demonstration of the the computer model that fits the light curve of the star J1407 seen in SuperWASP data in 2007. (M. Kenworthy/Leiden)
Mamajek said he and his team have been working with the American Association of Variable Star Observers (AAVSO), a large amateur astronomy organization, and that amateur astronomers have already contributed valuable assistance to the their findings. Any interested amateur astronomers who would like to help with the team’s continuing work in monitoring the J1407 system can do so through the AAVSO.
The new Kenworthy/Mamajek study outlining their findings has been accepted for publication in the Astrophysical Journal.
Dr. Eric Mamajek talked about this “Super Saturn” on a recent radio edition of Science World. You can listen to the interview in the player below.
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