Astronomers utilizing the NASA/ESA/CSA James Webb Space Telescope have found evidence of energy deposition in the upper atmosphere of the nearby brown dwarf SIMP J013656.5+093347.3 caused by auroras.

SIMP J013656.5+093347.3 (commonly referred to as SIMP-0136) is a low-mass brown dwarf located 20 light years away in the Pisces constellation, approximately 6.12 light years from Earth.

As part of the Carina-near Stellar Association, this celestial object is estimated to be around 200 million years old.

The mass of SIMP-0136 is roughly estimated to fall between 12.7 and 17.8 times that of Jupiter.

With a spectral type of T2.5 and a temperature nearing 1,100 K, it exhibits many atmospheric properties similar to those of directly imaged exoplanets, such as HR 8799B and AF Lep b.

“Our observations have illuminated the activity of the robust aurora of SIMP-0136, which warms its atmosphere, much like the auroras on Earth and the powerful auroras found on Jupiter.”

“These measurements represent some of the most precise assessments of the atmospheres of extreme objects to this date, with direct measurements of atmospheric changes occurring for the first time.”

“Furthermore, with temperatures exceeding 1,500 degrees Celsius, SIMP-0136 will display mild heat waves this summer.”

“Our specific observations indicated that we could precisely record temperature variations of less than 5 degrees Celsius.”

“These temperature fluctuations were linked to minor alterations in the chemical makeup of this free-floating planet, hinting at storms akin to the Great Red Spot on Jupiter.

Another unexpected finding was the constancy of cloud variability in SIMP-0136.

Changes in cloud coverage might typically lead to atmospheric changes, similar to the variability observed with patches of clouds and clear skies on Earth.

However, astronomers discovered that cloud coverage remains stable across the surface of SIMP-0136.

At SIMP-0136’s temperatures, these clouds are distinct from Earth’s, primarily composed of silicate grains reminiscent of beach sand.

“Different wavelengths of light are associated with various atmospheric features,” stated Dr. Nasedkin.

“Similar to observing color changes on Earth’s surface, the color variations of SIMP-0136 are driven by alterations in atmospheric properties.”

“Utilizing advanced models enables us to deduce atmospheric temperature, chemical composition, and cloud positioning.”

“This work is thrilling as it showcases that by leveraging cutting-edge modeling techniques on Webb’s advanced datasets, we can understand the processes driving global weather throughout our solar system.”

“Understanding these meteorological processes is crucial as we continue discovering and characterizing exoplanets in the future.”

“Currently, such spectroscopic variability observations are limited to isolated brown dwarfs, but large telescopes and future studies, along with the eventual establishment of a habitable world observatory, will allow us to explore the atmospheric dynamics of exoplanets ranging from gas giants like Jupiter to rocky planets.”

The team’s survey results will be published in the journal Astronomy and Astrophysics.

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E. Nasedkin et al. 2025. JWST Weather Report: Investigating temperature variations, aurora heating, and stable cloud coverage on SIMP-0136. A&A 702, A1; doi: 10.1051/0004-6361/202555370