Washington: A Saturn-like ringed planet in the constellation Centaurus has been discovered orbiting a sun-like star.
The scientists, led by Assistant Professor of Physics and Astronomy Eric Mamajek 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 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.
“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,’” said Mamajek.
If a spherical object merely passed in front of the star, the intensity of the light would gradually dim and reach a low point before gradually increasing. That was not the case with the star identified as 1SWASP J140747.93-394542.6.
The Rochester team discovered a long, deep, and complex eclipse event with significant on-and-off dimming. At the deepest parts of the eclipse, at least 95 percent of the light from the star was being blocked by dust.
The shape of the light curve was very similar to that of a well-researched star (EE Cephei), suggesting similar traits in the companion objects.
However EE Cephei differs in that it appears to be a thick protoplanetary disk transiting—or passing—in front a massive, hot star.
“We suspect this new star is being eclipsed by a low-mass object with an orbiting disk that has multiple thin rings of dust debris,” said Mamajek.
The star is similar in mass to the sun, but is much younger - about 16 million years old or 1/300th the age of the solar system - and it lies about 420 light years away.
“This marks the first time astronomers have detected an extrasolar ring system transiting a Sun-like star, and the first system of discrete, thin, dust rings detected around a very low-mass object outside of our solar system,” said Mamajek.
“But many questions remain about what exactly has been discovered.”
He said that the object at the centre of the ring system is either a very low-mass star, brown dwarf, or planet. The answer lies in the object’s mass.
The study will be published in the Astronomical Journal.