Odd eclipse reveals ‘Saturn on steroids’

A team of astrophysicists has discovered a Saturn-like ring system in the constellation Centaurus.
Led by Eric Mamajek , assistant professor of physics and astronomy at the University of Rochester, and the Cerro Tololo Inter-American Observatory, scientists used data from the international SuperWASP (Wide Angle Search for Planets) and All Sky Automated Survey (ASAS) project to study the light curves of young Sun-like stars in the Scorpius-Centaurus association—the nearest region of recent massive star formation to the Sun.

A light curve is a graph of light intensity over time, and one star in particular showed dramatic changes during a 54-day period in early 2007. University of Rochester graduate student Mark Pecaut and Mamajek discovered the unusual eclipse in December 2010.Imagine yourself sitting in a park on a sunny afternoon and a softball passes between you and the sun. The intensity of light from the sun would appear to weaken for just a moment. Then a bird then flies by, causing the intensity of the sunlight to again weaken—more or less than it did for the baseball, depending on the size of the bird and how long it took to pass. That’s the principle that allowed the researchers to discover a cosmic ring system.

“When I first saw the light curve, I knew we had found a very weird and unique object. 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.