'Saturn on steroids' discovered

Posted by Emma Woollacott

Astrophysicists have for the first time observed a Saturn-like ringed planet orbiting a star like our own.

The scientists, led by Assistant Professor of Physics and Astronomy Eric Mamajek of the University of Rochester and the Cerro Tololo Inter-American Observatory, used data from the international SuperWASP (Wide Angle Search for Planets) and All Sky Automated Survey (ASAS) project to identify the planet.

"After we ruled out the eclipse being due to a spherical star or a circumstellar disk passing in front of the star, I realized that the only plausible explanation was some sort of dust ring system orbiting a smaller companion — basically a 'Saturn on steroids'," says Mamajek.

It's the first time astronomers have detected an extrasolar ring system transiting a Sun-like star, and the first time that discrete, thin  dust rings have been found around a very low-mass object outside our solar system.

The object at the center of the ring system is either a very low-mass star, brown dwarf, or planet. The answer depends on whether or not it's big enough to sustain thermonuclear fusion reactions during its projected lifetime. If the object's mass is less tha.

Mamajek and his team hope to use southern hemisphere telescopes to establish the radial velocity of the star and detect the gravitational tug and light of the companion.

Along with the central object, Mamajek is interested in what is taking place in the two large gaps between the rings. Gaps usually indicate the presence of objects with enough mass to gravitationally sculpt the ring edges, and Mamajek thinks his team could be either observing the late stages of planet formation - if the transiting object is a star or brown dwarf - or possibly moon formation if it's a giant planet.

"Follow up observations of such eclipses may provide our first observational constraints on the formation and early evolution of moons around gas giant planets," says Mamajek.