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Thu February 9, 2012
Dr. Alice Quillen, University of Rochester - Extrasolar Planet Discovery
Albany, NY – In today's Academic Minute, Dr. Alice Quillen of the University of Rochester reveals the process used to detect and describe objects orbiting distant stars.
Alice Quillen is an associate professor of physics and astronomy at the University of Rochester where her research focuses on the dynamics of gas and stars in galaxies, the astrophysics of active galactic nuclei, and the dynamics of planetesimals in young planetary systems. She holds a Ph.D. in physics for Caltech.
Dr. Alice Quillen - Extrasolar Planet Discovery
In the past few years, hundreds of extrasolar planets have been discovered by searching for transits.
A transit occurs when a celestial body blocks or eclipses the light from a star. But the transit isn't always a simple matter of a planet passing in front of a star. A planet could be part of a large ring system that is orbiting and eclipsing-the star. A young star could be surrounded by a gas disk. A gas disk could be orbiting a star that is a member of a binary star system.
Because planets are small they block less than one percent of the light from a star. But in the case of a ring system or a disk -- both are much larger than a planet -- the star could disappear completely during the eclipse. Instead of lasting for just a few hours like a transit of the Sun by Venus or Mercury, an eclipse by a disk could last weeks or months.
These are clues that help us determine what is passing in front of a star many light-years from earth.
We searched hundreds of young stars in an archive containing millions of light curves --- these are graphs of brightness as a function of time -- and found a 30 day long and deep dip in the brightness of a young solar-type star that took place in 2007. In the deepest part of the eclipse more than 90% of the starlight was missing. We suspect a dusty ring system orbiting a smaller body such as a planet or a low mass star, caused the eclipse.
There are two other star systems that show eclipses by disks and both are visible with the naked eye. A search for dips in the brightness of more stars may uncover more eclipsing disk or ring systems!