Last week I came across this interesting story on the BBC website – an exoplanet which has been found to have a large ring system – the first such discovery to date. Saturn, of course, has the most famous ring system of any of the planets in our Solar System. They were visible to Galileo in 1610 when he first looked at Saturn, but he was not able to discern them as rings, this was first done by Dutch astronomer Christian Huygens, who also discovered Saturn’s largest moon Titan.
However, in fact Jupiter, Uranus and Neptune (the other three “gas giants”) also have ring systems, although they are much fainter and less extensive than Saturn’s. Uranus’ ring system was discovered by SOFIA’s predecessor, the Kuiper Airborne Observatory, in 1977. Jupiter’s ring system was the next to be discovered, by the Voyager 1 space probe in 1979. Neptune’s ring system was discovered in 1984 using a ground-based telescope at La Silla Observatory (the European Southern Observatory), and were later imaged by Voyager 2 in 1989.
The ring system discovered about this exoplanet has been found by a survey known as SuperWASP, which is a ground-based survey looking for exoplanets using the transit method (which I discussed here). The exoplanet is orbiting a star by the name of J1407, which lies about 420 light years from Earth. This star had been found to have a peculiar light curve, not fitting the light curve one sees when a “normal planet” transits it. Further analysis by the authors of this work, led by Dr. Kenworthy at Leiden Observatory in the Netherlands, suggests that the complexity in the light curve is due to the transiting planet having a ring system. Here is a link to the abstract of the team’s paper on the arXiv preprint website.
The ring system is measured to be about 200 times larger than that around Saturn. Such a ring system would appear to be so large that, if Saturn’s ring system (which is impressive in its own right) were replaced by this one then the rings would be clearly visible from Earth, as this artist’s sketch attempts to show.