Using light-curve analysis astronomers have found a strange, dust-ringed object orbiting a distant star. They all agree it's like a 'Saturn on steroids,' but what actually is rolling around inside those dust rings?
Taking a look at a star's light-curves has been a common way of finding extrasolar planets. The planets are too dim to be seen themselves, even if they're reflecting the light from the star they orbit. But if they're big enough and their orbit is tight enough, they cause a slight change in the light coming from the star. That dip in light can be measured. The same way enough experience can teach a person if someone is completely blocking the light from a nearby lamp or if someone is just sticking their hand in front of the bulb, experience can teach instruments to determine the difference between light from an unimpeded star and light from a star that is partially blocked by a planet.
Or blocked by a . . . something. In 2007, light readings were taken of the poetically-named star '1SWASP J140747.93-394542.6'. Instead of the light dimming to a low point and brightening again, the way it does when single planets move in front of a star, the star's light went through a long, slow flicker dimming and brightening to different levels. At one level, ninety-five percent of the star's light was blocked. Whatever was passing in front of the star, it had to be pretty big. The object has been hard to see, considering it's 420 light-years away, and scientists don't exactly know what it is yet. What they do know, according to one of the lead scientists, Eric Mamajek of the University of Rochester, is that it has a ring on it.
"After we ruled out the eclipse being due to a spherical star or a circumstellar disk passing in front of the star," Dr. Mamajek said, "I realized that the only plausible explanation was some sort of dust ring system orbiting a smaller companion-basically a 'Saturn on steroids.'"
Their best guess is that the ringed object is a brown dwarf, about thirteen to seventy-five times the size of Jupiter, that never got big enough to sustain thermonuclear reactions in its core and become a star. As for the rings, they're probably formed by large objects carving out gaps between the central objects and the dust around them. There are plenty of disks of dust out there, but the presence of rings indicates that moons around the central object are forming. The full results will be published in an upcoming issue of The Astronomical Journal.
The next step will be to take a closer look at the original star, and see what the gravitational activity between it and the mystery object can reveal. Depending on the activity, the ringed object could either be a brown dwarf or a very large planet. Although the 16 million year old system is unlikely to have life in any form, it is a new and mysterious object out there in the universe.