Thursday, May 20, 2021

The new lord of the rings

The rings of Saturn are undoubtedly one of the greatest wonders of the Solar System.

In the Milky Way, however, there are other planets surrounded by systems of rings, some of which are much larger than the Saturnian one.

This is the case of J1407b, an exoplanet orbiting a Sun-like star 560 light-years away from Earth.

At the time of its discovery in 2007 through the transit method, astronomers immediately realized that this planet had some oddities.

In fact, when an exoplanet moves along its orbit and passes in front of its star, it causes a periodic decrease in light. In the case of J1407b this decrease was very complex and could only be explained by assuming that the planet was surrounded by a system of rings.

Subsequent spectroscopic observations made it possible to accurately determine the characteristics of the exoplanet. J1407b turned out to be a gas giant with a mass between 30 and 130 of Saturn masses (in the latter case it would therefore be a brown dwarf and not a gas giant).

The most surprising results, however, were those regarding the size of the ring system: these turned out to have a diameter of 120 million km, almost 200 times the extension of Saturn's rings!

The combined mass of these rings is estimated to be comparable to that of the Earth!

It is not yet known what could have led to the formation of such a vast ring system and above all how it manages to remain stable.

Surely the rings of J1407b must rotate in the opposite direction to what the planet does around its star, otherwise the configuration would be unstable and the rings would disintegrate in a short time.

Credit: Ron Miller.

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