海角精品黑料-led team maps 鈥榳eather鈥� on a nearby brown dwarf in unprecedented detail
Researchers at 海角精品黑料 and collaborating institutions have mapped the atmospheric features of a planetary-mass brown dwarf, a type of space object that is neither a star nor a planet, existing in a category in-between. This particular brown dwarf鈥檚 mass, however, is just at the threshold between being a Jupiter-like planet and a brown dwarf. It has thus also been called a free-floating, or rogue, planet, not bound to a star. Using the James Webb Space Telescope (JWST), the team captured subtle changes in light from SIMP 0136, revealing complex, evolving weather patterns across its surface.
鈥淒espite the fact that right now we cannot directly image habitable planets around other stars, we can develop methods of learning about the meteorology and atmospheric composition on very similar worlds,鈥� said Roman Akhmetshyn, a 海角精品黑料 MSc student in physics and the 's lead author.
SIMP 0136 sits about 20 light-years away in the direction of the constellation Pisces. With a mass about 13 times that of Jupiter, it鈥檚 too small to sustain the nuclear fusion that powers stars, but too large to be considered an ordinary planet. It probably formed like a star before cooling and dimming over hundreds of millions of years.
SIMP 0136 is a free-floating planet, drifting alone through space, and its isolated environment makes it an ideal laboratory for studying the atmospheres of gas giants without interference from starlight.
Peering into alien clouds
The researchers used JWST鈥檚 Near-Infrared Imager and Slitless Spectrograph (NIRISS), a Canadian-built instrument developed by the Canadian Space Agency, the Universit茅 de Montr茅al (UdeM) and other partners, to observe the object for a full rotation, lasting only 2.4 hours. These data were collected as part of a Guaranteed Time Observations program led by UdeM astronomer 脡tienne Artigau. This time on the telescope was reserved for Canadian astronomers in exchange for the contribution of the NIRISS instrument to the JWST mission.
By analyzing minute fluctuations in brightness at different wavelengths, the team discovered that SIMP 0136鈥檚 light is shaped by at least three distinct atmospheric layers. Each layer contains clouds made of different materials, such as forsterite (a rock) and iron, with varying temperatures and chemical compositions.
鈥淲e suspect numerous small-scale patchy clouds of different temperatures and chemistry, scattered across the globe,鈥� said Akhmetshyn. "Although we couldn't create a meteorological map of SIMP 0136, we determined that some atmospheric layers have clear signs of north-south asymmetry."聽This asymmetry is important since it means that future efforts to map the atmospheres of these planets will have to do so in two dimensions: longitude and latitude.
A new way to study exoplanet atmospheres
The study also showed that no single model could explain the observed data; only a combination of several atmospheric models could reproduce the spectrum. That finding supports theories that brown dwarfs and giant exoplanets have chaotic, fast-changing weather, similar to Jupiter鈥檚 bands but far more turbulent.
Understanding such variability could help scientists interpret signals from distant exoplanets.
The work demonstrates the power of JWST to probe alien worlds beyond our solar system in unprecedented detail. As Webb continues to observe similar targets, researchers hope to refine their techniques to map not just temperature and clouds, but also wind patterns and chemical cycles on alien worlds.
About the study
by Roman Akhmetshyn (海角精品黑料), 脡tienne Artigau (Universit茅 de Montr茅al), Nicolas B. Cowan (海角精品黑料), and collaborators was published in The Astrophysical Journal聽(DOI:10.3847/1538-4357/ae046d ). This research was funded by CSA General Observers (GO) funding, the FRQNT鈥檚 Science en exil program, and a Mitacs Globalink Graduate Fellowship.
