New analysis of available data by astronomers at the Leiden Observatory, The Netherlands, and the University of Rochester in New York, published 22 Jan. 2015, in the Astrophysical Journal, has established that a ring system, first discovered in 2012 around the young giant planet or brown dwarf J1407b, is two hundred times larger and much heavier than the ring system of Saturn.
The new ring system is the first of its kind to be detected anywhere outside our solar system. Professor Eric Mamajek of the University of Rochester, who co-authored the study, told the BBC, “You could think of it as kind of a super Saturn.”
The system was first discovered in 2012 by a team of researchers at the University of Rochester, led by Professor Mamajek. The team detected the ring system after observing an unusual pattern of eclipses of a newly discovered Sun-like star, called J1407.
The parent star J1407, about 420 light years away, is believed to be about the same mass as the Sun, but younger, about 16 million years old.
Based on their measurements of the patterns of deep eclipses of star light from J1407, the astronomers concluded that the eclipses were caused by a disk formed around a young giant planet or brown dwarf orbiting the star J1407.
They named the giant planet J1407b.
In subsequent analyses, the astronomers were able to determine the size and mass of the ring system by analysis of data obtained from the SuperWASP project designed to detect gas giant planets as they move in front of their parent star.
Although, the star J1407 and its system, including J1407b, are too far away for astronomers to observe directly, they have been able to estimate the size and mass of the ring system by modeling it using data pertaining to “rapid brightness variations” in light passing from the star to observers through the obscuring ring system.
“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.”
The data analysis to estimate the size and mass of the ring involved the use of methods, such as “adaptive optics and Doppler spectroscopy.” The researchers concluded from their analysis that J1407b is a giant planet with a huge ring system and that the ring system was causing the observed patterns of eclipses of the light of the parent star J1407.
The latest data analysis, led by Leiden’s Matthew Kenworthy, reveals that the ring system consists of over 30 rings. Each ring is tens of millions of kilometers in diameter.
The researchers estimated the diameter of the ring system at nearly 120 million kilometers, more than two hundred times the diameter of Saturn’s rings. They also estimated that the ring system contains light obscuring dust particles about the mass of Earth or Mars.
The team found gaps in the rings which indicate that satellites or “exomoons” of J1409b were forming in the system. According to Mamajek, the giant “planet is much larger than Jupiter or Saturn and its ring system” about “200 times larger than Saturn’s.”
“This planet is much larger than Jupiter or Saturn, and its ring system is roughly 200 times larger than Saturn’s rings are today. You could think of it as kind of a super Saturn.”
To help put into context the mass of the rings, Mamajek gave an illustration.
“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. 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.”
The astronomers predicted that the massive ring will shrink gradually in the next millions of years and disappear altogether as the material forming the rings is used to form new satellites of the giant planet.
“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. 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.”
The orbital period of J1407b around its parent star is estimated to be about a decade in length. The mass of the planet is estimated at about 10 to 40 times that of Jupiter.
The researchers have asked amateur astronomers to help sharpen their estimation of the mass and period of J1407b by reporting observations of the next eclipse to the American Association of Variable Star Observers (AAVSO).
[Images: Univ. Of Rochester/Kenworthy/Leiden/Ron Miller]