Dr Matthew Kenworthy of Leiden Observatory and Prof Eric Mamajek of the University of Rochester have discovered a so-called super-Saturn exoplanet with an enormous ring system circling the very young Sun-like star 1SWASP J140747.93-394542.6 (for short J1407).
The rings of J1407b are shown eclipsing the young Sun-like star J1407. Image credit: Ron Miller.
J1407 is a pre-main sequence 16-million-year-old star located approximately 434 light-years away. It is orbited by at least one planet, named J1407b.
Prof Mamajek and Dr Kenworthy estimate that the planet has an orbital period of about 10 years. Its mass is most likely in the range of about 10 to 40 Jupiter masses.
“J1407b 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,” said Prof Mamajek, who is a co-author of a paper accepted for publication in the Astrophysical Journal (arXiv.org preprint).
According to the astronomers, J1407b’s ring system consists of about 37 rings, each of them tens of millions of kilometers in diameter.
Furthermore, they found gaps in the rings, which indicate that exomoons may have formed.
“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,” Dr Kenworthy said.
“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 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’s worth of mass in light-obscuring dust particles.
Prof 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.
“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 expect that J1407b’s rings will become thinner in the next several million years and eventually disappear as satellites form from the material in the disks.
They encourage amateur astronomers to help monitor J1407, which would help detect the next eclipse of the rings, and constrain the period and mass of J1407b.
_____
Matthew A. Kenworthy & Eric E. Mamajek. 2015. Modeling giant extrasolar ring systems in eclipse and the case of J1407b: sculpting by exomoons? ApJ, accepted for publication; arXiv: 1501.05652
