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Pioneering imager at Georgia State's CHARA Array gives sharpest view of stars, planet-forming disks

Georgia State University


IMAGE: This is Douglas Gies, Regents' Professor of Astronomy at Georgia State University and director of CHARA view more 

Credit: Georgia State University

ATLANTA--A pioneering new instrument that can produce the sharpest images of young stars is now available for use by scientists worldwide.

The instrument, called MIRC-X, will give astronomers a fascinating glimpse into how our solar system may have looked when it first formed. MIRC-X is installed at Georgia State University's Center for High Angular Resolution Astronomy (CHARA) Array, which is located on Mount Wilson in California. The CHARA Array incorporates six, one-meter telescopes spread over an area of 330 meters in diameter. The MIRC-X instrument combines the light from all six telescopes at the same time, effectively creating the resolving power of a giant 330-meter telescope.

"The MIRC-X camera will show details of young planet forming regions never seen before," said Douglas Gies, Regents' Professor of Astronomy at Georgia State and director of CHARA. "We have plans to explore all kinds of stars with this new instrument."

An international team of experts, including astronomers from the University of Exeter (U.K.), the University of Michigan and Georgia State, created the MIRC-X imager to gain new insights into how planets form from the rotating, circumstellar disks of dense dust and gas that develop around young stars. While conventional telescopes can only see the outer disk region of these fledgling stars because of the sheer distance they are found from Earth, the new imager can produce images from the depths of the disk close to the star.

"The big prize in planet formation studies is to understand what happens in the very inner regions of these disks, on the scales where Earth is located in our solar system," said professor Stefan Kraus, principal investigator from the University of Exeter's Physics and Astronomy Department. "In these inner regions, the disk undergoes a dramatic transition from a dust and gas composition to a purely gaseous disk. The strong pressure gradient there might lead to a pileup of dust grains that could trigger the formation of rocky planets."

"We needed a camera with extremely low noise, but at the same time also a very high frame rate in order to freeze any image distortion introduced by the atmosphere," Kraus said. "Fortunately, there was a real breakthrough in detector technology that has resulted in a new generation of infrared cameras. We now have the world's fastest, low noise, infrared camera, and it is close to reaching the fundamental physical limit of single photon detection, making it nearly perfect for our purposes."

The CHARA Array actually reconstructs images from data, rather than capturing direct images, and the MIRC-X instrument provides much better data quality, said Fabien Baron, assistant professor in the Department of Physics and Astronomy at Georgia State. Baron's research team switched to the MIRC-X instrument in order to study faint objects in the galaxy.

In late 2018, the international team that created the MIRC-X imager achieved "first light," the moment when the new instrument captured starlight for the first time.

"We were off to a successful start of our observing campaign and can't wait to analyze the data that we recorded," Kraus said. "The images will show us what the solar system might have looked like 4.6 billion years ago, at the time when Earth and the other planets formed."


The MIRC-X project received funding from the European Research Council. The CHARA Array is funded by the U.S. National Science Foundation and Georgia State's College of Arts and Sciences.

Scientists can apply for observing time by submitting project ideas to the National Optical Astronomy Observatory. For more information, visit

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