One of the brown dwarfs nearest to Earth may look like a darker version of Jupiter, the largest planet in the solar system. A new study, which provides the most detailed look at a brown dwarf’s atmospheric patterns to date, found that horizontal bands of thick clouds may alternate with relatively cloud-free bands, giving the object a striped appearance. Also like Jupiter, whirling storm systems as big as terrestrial continents may dominate the brown dwarf’s polar regions. Combined with findings from earlier studies, the report suggests that many brown dwarfs may exhibit a similar appearance.

A brown dwarf, often described as a failed star, is more massive than a giant planet but not massive enough to sustain fusion reactions in its core and shine as a true star. Brown dwarfs typically are about the same size as Jupiter but can be dozens of times more massive.

Scientists, who published their research in the Astrophysical Journal in January, used the Transiting Exoplanet Survey Satellite (TESS) to observe the binary brown dwarf system Luhman 16 AB. At a distance of just 6.5 light-years, its two objects are the brown dwarfs closest to Earth. Because the system is faint, however, it wasn’t discovered until 2013, and scientists are just beginning to study it. They’ve found that Luhman’s primary brown dwarf, A, is about 34 times the mass of Jupiter, with B tipping the scales at more than 28 times Jupiter’s mass.

TESS provided the most extensive observations of any brown dwarf to date. The satellite, which is designed to detect planets passing across the faces of nearby dwarf stars, stares at a small patch of sky for roughly 4 weeks before moving on to the next search area. Its cameras record other objects in addition to exoplanet transits, including variable stars, exploding stars, and brown dwarfs.

Luhman 16 was in the craft’s viewing field during March and April of 2019. TESS observed the system every 30 minutes.

“This data set’s continuous coverage of nearly 22 days straight is what really sets it apart,” said Max Millar-Blanchaer, an assistant professor of physics at the University of California, Santa Barbara who has also found evidence of clouds on Luhman 16 but was not a member of this team. “Never before have we been able to monitor the weather in a brown dwarf continuously for so long.”

Analysis revealed several periods in the system’s light curve, including one of almost 7 hours, which probably represents the rotation rate of the A component, and another of almost 91 hours, which may be dominated by vortices at the poles of B.