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Mason researchers part of a team that discovered a new planet the size of Neptune

July 16, 2020   /   by John Hollis

An artist's rendering of the AU Mic star system. Provided by NASA’s Goddard Space Flight Center.

A George Mason University professor and four of his students are part of a research team that has discovered a new planet the size of Neptune that could provide clues about the possibility of life beyond Earth. 

Peter Plavchan, an assistant professor within the Department of Astronomy and Physics within the College of Science and the director of the Mason Observatory, and doctoral student Bryson Cale helped author a study in the journal Nature that detailed the discovery of AU Mic b. 

“Since this planet is so young, we know its atmosphere is ‘primordial,’ so it will be very interesting to learn what its atmosphere is made of to better understand the planet formation process,” said Plavchan, the study’s lead. “We’d also like to know whether or not the planet formed where it is today, or if it formed in a different location, but quickly migrated to its current location. Since the planet is so young, dynamical changes to the planet’s orbit had to take place very quickly. Otherwise, it must have formed where it is currently located and, if that’s true, it presents a big puzzle for how these planets form so quickly that astronomers don’t fully understand yet.” 

Other authors of the study include Thomas Barclay, a University of Maryland associate professor and scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland; the University of New Mexico’s Diana Dragomir; and Mason undergraduate Natasha Latouf. 

Other Mason students working on the project include undergraduate Ben Tieu and PhD candidate William Matzko. 

Like other exoplanets that orbit a star rather than our sun, AU Mic b could also offer astronomers key insights into the formation and development of planets and their migration patterns. 

The newest planet, which is part of the AU Microscopii star system, lies relatively close to Earth at roughly 32 light years away and can easily be observed. Discovered by NASA’s exoplanet-hunting Transiting Exoplanet Survey Satellite (TESS) and its retired Spitzer Space Telescope, AU Mic b is estimated to be between 20 million and 30 million years old. 

“AU Mic is a young, nearby M dwarf star,” Cale said in a statement released by NASA. “It’s surrounded by a vast debris disk in which moving clumps of dust have been tracked and now, thanks to TESS and Spitzer, it has a planet with a direct size measurement. There is no other known system that checks all of these important boxes.” 

Plavchan first began studying exoplanets in 2001 while in graduate school at UCLA and specifically AU Mic b in 2010. Cale joined his research group as a graduate student in 2016 and followed Plavchan to Mason a year later to join the department’s PhD program. 

“For the human race, we’ve answered a question that we’ve wondered for a millennia, dating back to Ancient Greece and probably since the dawn of human consciousness,” Plavchan said. “Are there other worlds out there? Now we know the answer is yes. And now, we’ve found a planet that will help us understand how they form.” 

Go here if you want to listen to the students talk about exoplanets and their research.