Massive COCONUTS Exoplanet Discovery: Giant Planet Just 35 Light Years From Earth

Planet COCONUTS-2b

Illustration of gas-giant planet COCONUTS-2b. Credit: B. Bays (SOEST/UH)

Astronomers have discovered thousands of exoplanets — planets beyond our solar system — but few have been directly imaged, because they are extremely difficult to see with existing telescopes. A University of Hawaiʻi Institute for Astronomy (IfA) graduate student has beaten the odds and discovered a directly imaged

Zhang Researchers Zoom

During the pandemic, Zhang met with fellow researchers on Zoom to discuss the discovery

Using the COol Companions ON Ultrawide orbiTS (COCONUTS) survey, IfA graduate student Zhoujian Zhang and a team of astronomers, Michael Liu and Zach Claytor (IfA), William Best (University of Texas at Austin), Trent Dupuy (University of Edinburgh) and Robert Siverd (Gemini Observatory/National Optical-Infrared Astronomy Research Laboratory) identified a planet about six times the mass of

Jupiter Hubble

The exoplanet is about six times the mass of planet Jupiter.

“With a massive planet on a super-wide-separation orbit, and with a very cool central star, COCONUTS-2 represents a very different planetary system than our own solar system,” Zhang explained. The COCONUTS survey has been the focus of his recently-completed PhD thesis, aiming to find wide-separation companions around stars of all different types close to Earth.

Zhoujian Zhang

IfA graduate student Zhoujian Zhang

Trapped heat helps detect planet

COCONUTS-2b is the second-coldest imaged exoplanet found to date, with a temperature of just 320 degrees

Michael Liu

IfA astronomer Michael Liu

Darkness prevails

Due to its wide-separation orbit and cool host star, COCONUTS-2b’s skies would look dramatically different to an observer there compared to the skies on Earth. Nighttime and daytime would look basically the same, with the host star appearing as a bright red star in the dark sky.

Zhang’s discovery has fueled his desire to continue to explore exoplanets, brown dwarfs, and stars. The aspiring astronomer graduated from IfA this summer and will begin his postdoctoral research in fall 2021, with IfA alumnus Brendan Bowler, an astronomy professor at the University of Texas at Austin.

Reference: “The Second Discovery from the COCONUTS Program: A Cold Wide-orbit Exoplanet around a Young Field M Dwarf at 10.9 pc” by Zhoujian Zhang, Michael C. Liu, Zachary R. Claytor, William M. J. Best, Trent J. Dupuy and Robert J. Siverd, 28 July 2021, The Astrophysical Journal Letters.

DOI: 10.3847/2041-8213/ac1123