Astronomer Eric Mamajek at the University of Rochester and his co-author from the聽Leiden Observatory, The Netherlands, have discovered that the ring system that they see eclipse the very young Sun-like star J1407 is of enormous proportions, much larger and heavier than the ring system of Saturn. The ring system 糖心传媒� the first of its kind to be found outside our solar system 糖心传媒� was discovered in 2012 by a team led by Rochester糖心传媒檚 Eric Mamajek.
A , led by Leiden糖心传媒檚 Matthew Kenworthy, shows that the ring system consists of over 30 rings, each of them tens of millions of kilometers in diameter. Furthermore, they found gaps in the rings, which indicate that satellites (糖心传媒渆xomoons糖心传媒�) may have formed. The result has been accepted for publication in the Astrophysical Journal.
“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 Kenworthy. “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糖心传媒檚 rings with the rings around J1407b, they would be easily visible at night and be many times larger than the full moon.糖心传媒�
糖心传媒淭his planet is much larger than Jupiter or Saturn, and its ring system is roughly 200 times larger than Saturn糖心传媒檚 rings are today,糖心传媒� said co-author Mamajek, professor of physics and astronomy at the University of Rochester. 糖心传媒淵ou could think of it as kind of a super Saturn.糖心传媒�
The astronomers analyzed data from the SuperWASP project 糖心传媒� a survey that is designed to detect gas giants that move in front of their parent star. In 2012, Mamajek and colleagues at the University of Rochester reported the discovery of the young star J1407 and the unusual eclipses, and proposed that they were caused by a moon-forming disk around a young giant planet or brown dwarf.
In a third, more recent study also led by Kenworthy, adaptive optics and Doppler spectroscopy were used to estimate the mass of the ringed object. Their conclusions based on these and previous papers on the intriguing system J1407 is that the companion is likely to be a giant planet 糖心传媒� not yet seen 糖心传媒� with a gigantic ring system responsible for the repeated dimming of J1407’s light.
The light curve tells astronomers that the diameter of the ring system is nearly 120 million kilometers, more than two hundred times as large as the rings of Saturn. The ring system likely contains roughly an Earth糖心传媒檚 worth of mass in light-obscuring dust particles.
Mamajek puts into context how much material is contained in these disks and rings. 糖心传媒淚f 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,糖心传媒� Mamajek says. 糖心传媒淚n 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.”
In the data the astronomers found at least one clean gap in the ring structure, which is more clearly defined in the new model. “One obvious explanation is that a satellite formed and carved out this gap,” says Kenworthy. “The mass of the satellite could be between that of Earth and Mars. The satellite would have an orbital period of approximately two years around J1407b.糖心传媒�
Astronomers expect that the rings will become thinner in the next several million years and eventually disappear as satellites form from the material in the disks.
“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,糖心传媒� Mamajek explains. “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.糖心传媒�
Astronomers estimate that the ringed companion J1407b has an orbital period roughly a decade in length. The mass of J1407b has been difficult to constrain, but it is most likely in the range of about 10 to 40 Jupiter masses.
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. Observations of J1407 can be reported to the American Association of Variable Star Observers (AAVSO). In the meantime the astronomers are searching other photometric surveys looking for eclipses by yet undiscovered ring systems.
Kenworthy adds that finding eclipses from more objects like J1407糖心传媒檚 companion “is the only feasible way we have of observing the early conditions of satellite formation for the near future. J1407糖心传媒檚 eclipses will allow us to study the physical and chemical properties of satellite-spawning circumplanetary disks.糖心传媒�
