WISE J0336−0143

Lore & Background

The system was first suspected to be a binary after follow-up observations revealed an unusual infrared spectrum, but its binarity was not confirmed until the James Webb Space Telescope resolved the components in high-resolution NIRCam imaging in September 2022, with results published in March 2023. The two components orbit their barycenter approximately every 7 years and are separated by 0.97 astronomical units, slightly less than the distance between the Sun and Earth. The brighter primary has a temperature and mass range near the deuterium fusion threshold of 13 Jupiter masses, while the fainter secondary also falls in a similar mass range. Because the system's age and evolutionary stage have not been determined, the individual masses remain uncertain, though both appear near the boundary between gas giant planets and brown dwarfs.

Reader's Guide

The secondary component, WISE J0336−0143 B, might be one of the coldest objects in interstellar space discovered so far. Newer models of Y dwarfs produce an even colder temperature for it. WISE 0855−0714 remains the coldest object found so far, and WISE J0830+2837 has a similar temperature. Models suggest that WISE J0336−0143 B might have water clouds, but changes in the pressure–temperature profile might instead explain the color of cold Y dwarfs. JWST photometry shows that WISE J0336−0143 B is significantly bluer than WISE 0855−0714, a blue color seen as a likely indicator of water ice clouds. The study of such low-mass binary systems provides valuable insight into the formation and evolution of planetary-mass objects.

Did You Know?

• The system was discovered in WISE images and formally published in March 2013.
• Binarity was confirmed by JWST NIRCam imaging in September 2022.
• The two components orbit every ~7 years at a separation of 0.97 AU.