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Doctoral student announces ‘exoplanet’ discovery

by Judy Hughes, communications and marketing last modified Jun 04, 2013 02:36 PM

A scientific team led by University of Louisville doctoral student Karen Collins has discovered a hot Saturn-like planet in another solar system 700 light-years away.

Doctoral student announces ‘exoplanet’ discovery

Physics and astronomy professor John Kielkopf, research engineer Jeff Hay and doctoral student Karen Collins at UofL's Moore Observatory.

Collins announced the discovery of exoplanet KELT-6b June 4 during the American Astronomical Society’s national meeting in Indianapolis. KELT stands for the Kilodegree Extremely Little Telescope project.

Astronomers caught sight of the planet when it passed in front of, or “transited,” its host star. They made the discovery using inexpensive ground-based telescopes, including one specially designed to detect exoplanets and jointly operated by KELT project astronomers at Ohio State University and Vanderbilt University.

As seen from Earth, KELT-6b resides in the constellation Coma Berenices, near Leo, and has an orbit that transits its star every 7.8 days. That means a “year” on the planet lasts just over a week, and its trip across the face of its star, as seen from Earth, lasts only five hours.

Most planets that ground-based telescopes find have even shorter orbits, so catching a complete observation of KELT-6b took more patience and substantially more luck than usual – a total of seven hours of continuous telescope time with clear skies during darkness.

Collins had clear skies on both of her only two opportunities to catch the planet earlier this year at UofL’s Moore Observatory.

“To participate in planet discovery here in Kentucky, it’s just incredible to me to be able to do that,” she said. Her work is supported by a NASA Kentucky Space Grant Consortium graduate fellowship.

The KELT project operates two telescopes: the KELT North telescope in Arizona and its twin, KELT South in South Africa. While they are no more powerful than high-end digital cameras, they’ve proven that small telescopes can make big planet discoveries. KELT North briefly glimpsed the new planet last year, but the team needed help with follow-up observations to capture the entire transit, explained Scott Gaudi, associate professor of astronomy at Ohio State and member of the KELT team.

The KELT telescopes record images of huge swaths of night sky. Scientists search for slight, periodic dimming of any stars in the images, which could indicate a planet transiting its star. Once the slight variation in light is detected, scientists use other telescopes to determine exactly which star is affected and precisely how much it dims.

Collins was able to make the critical observations.

 

“Karen chased the planet down and got the data that we needed to ask for precious Keck time,” Gaudi said, referring to the high-powered twin Keck Observatory telescopes in Hawaii. “With the Keck data, we were able to take a much closer look and confirm the discovery of KELT-6b.”

“She developed the technique that enabled her to make this precise measurement of the dimming of the star,” said John Kielkopf, UofL professor of physics and astronomy. “She didn’t just sit down at the telescope….She had to develop the ways in which the instrument we had could extract this data.”

Collins and her team determined KELT-6b is a hot gas-giant planet orbiting a star about the same age as our sun. The planet resembles our own Saturn in size and mass but has no rings. It also resembles the most studied exoplanet, HD 209458b, but differs because it was formed in an environment low in metals, meaning elements heavier than hydrogen and helium. By comparing the exoplanets, scientists hope to learn more about their atmospheres and the evolution of planetary systems.

Kielkopf and Gaudi, along with Keivan Stassun, Vanderbilt astronomy professor and KELT team member; Thomas Beatty, a doctoral student at Ohio State; and Joshua Pepper, Lehigh University assistant professor of physics, all partnered with Collins on her discovery. Additional funding for the work came from the National Science Foundation, NASA and Vanderbilt University.

Collins, who plans to graduate with her doctorate in 2014, is working to confirm and characterize a second body in the same system as KELT-6b. An electrical engineer whose longtime fascination with astronomy led her to this second career, she called the work “an adventure.”

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