Saturn-mass planet co-discovered by Westminster College professor, students

Members of the Westminster College Observatory research team (left to right): Ryan Avril, Sarah Mauri, Samuel Mellon, and Dr. Thomas Oberst. Electronic image by Brett McElroy.

NEW WILMINGTON, Pa. – A Saturn-mass exoplanet (a planet that orbits other stars) has been co-discovered by Dr. Thomas Oberst, Westminster College assistant professor of physics, and undergraduate students Ryan Avril and Samuel Mellon. The planet, named KELT-6b, orbits a star more than 700 light-years away in the constellation Coma Berenices. It is the first planet that Westminster College has helped discover.

An article detailing the discovery was published on Saturday in the February issue of the Astronomical Journal. The lead author of the article is Karen Collins of the University of Louisville. Oberst, Avril, and Mellon are coauthors. The authors first announced the planet at the 222nd meeting of the American Astronomical Society  in June.

To view the article. visit http://iopscience.iop.org/1538-3881/147/2/39/.

“We feel privileged to have had the opportunity to be part of this discovery, which required the work of more than 40 members of the KELT-North team,” Oberst said. “Discovering strange new worlds like this helps put our own solar system  and planet in context.”

KELT-6b was found to have a mass near that of Saturn, but orbits its host star more than 100 times closer than Saturn. Thus, the star’s heat has caused KELT-6b to swell to a diameter 50 percent larger than Saturn, and has likely vaporized  any rings the planet may have had. “There is no chance of life on this planet,” Oberst added.

Because exoplanets are difficult to photograph directly, Oberst, Avril, and Mellon detected KELT-6b using the transit technique, whereby the planet’s host star was observed to dim as the planet passed in front of the star during its orbit.  Although several hundred transiting exoplanets have been confirmed, KELT-6b has one of the 20 brightest host stars, making it especially conducive to follow-up studies. The host star is also especially deficient in metals, providing a test-case for how metals  influence planet formation and evolution.

The planet’s transit was first spotted by the Kilodegree Extremely Little Telescope (KELT) North, a robotic telescope in Arizona operated by astronomers at the Ohio State University and Lehigh University. Oberst, Avril, and Mellon then  observed the transit more precisely using a larger telescope at the Westminster College Observatory, helping to confirm that it was indeed due to a planet, rather than a binary star or other type of false-positive.

Oberst, who has been with Westminster since 2008, earned an undergraduate degree from Duquesne University and master’s and Ph.D. from Cornell University. Avril, a senior physics major, is a son of Robert Avril and Susan Avril and a graduate of Jamestown Area High School.Mellon, a senior physics major, is a son of David and Martha Mellon and a graduate of Bradford Area High School.

Contact Oberst at 724-946-7204 or e-mail oberstte@westminster.edu for additional information on exoplanets.

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