Using the James Webb Space Telescope, an international team of researchers has uncovered the hidden complexity of SIMP 0136, a free-floating planetary-mass object.
Previously observed brightness changes in SIMP 0136 can no longer be explained by clouds alone; a mix of atmospheric factors, including patchy clouds, temperature changes, and carbon chemistry, is at play.
What makes SIMP 0136 special?
Located 20 light-years away in the Milky Way, SIMP 0136 is about 13 times the mass of Jupiter and rotates rapidly, completing one spin every 2.4 hours. Despite not orbiting a star, it shines as the brightest object of its kind in the northern sky, making it perfect for studying gas giant atmospheres without interference from starlight.
Key findings Using infrared data collected over two rotations, researchers detected atmospheric features never seen before:
Patchy clouds: Made of iron and silicate particles at different depths.
Hot spots: Linked to temperature changes and possibly auroras.
Mid-level clouds: Others indicated silicate-based clouds, also contributing to brightness variations.
High-altitude layers: Light from these regions reflected temperature changes, possibly linked to auroras or hot gas rising from deeper levels.
Carbon chemistry variations: Areas of carbon monoxide and dioxide appear to shift, suggesting dynamic chemical processes.
Webb Telescope used its NIRSpec and MIRI instruments to study SIMP 0136, capturing detailed infrared data during two full rotations. NIRSpec recorded thousands of light spectra every 1.8 seconds over three hours, while MIRI gathered hundreds of measurements every 19.2 seconds for another rotation. This produced hundreds of light curves, showing brightness changes at various wavelengths as different parts of the object rotated into view.
Lead researcher Johanna Vos called the results groundbreaking, revealing dynamic atmospheric changes that were previously unseen. The team observed distinct patterns—some wavelengths grew brighter, others dimmer—indicating multiple factors affecting brightness.
Co-researcher Philip Muirhead compared it to viewing Earth from space, where different colors reveal surface and atmospheric details, like oceans or vegetation. The findings highlight the complexity of SIMP 0136’s atmosphere.
Why it matters?
This discovery provides a three-dimensional view of gas giant atmospheres, improving our understanding of planets both within and beyond our solar system.
The graphic has two parts. On the left are light curves showing the change in brightness of three sets of near-infrared wavelengths over time. On the right is a cross-section of the object’s atmosphere, showing the altitude that each set of wavelengths originates and their relationship to cloud layers or temperature. Credit: NASA, ESA, CSA, J. Olmsted (STScI)
“It’s like watching Earth from far away, where every color reveals something new about its atmosphere,” said co-author Philip Muirhead.
A mysterious population of free-floating planets uncovered
Though mysteries remain, such as the exact role of atmospheric chemistry, the research highlights the complexity of objects like SIMP 0136. The study could also improve how we interpret data from exoplanets in the future.
Published in The Astrophysical Journal Letters, this breakthrough demonstrates the power of the James Webb Telescope in unraveling the cosmic unknown.
Interestingly, certain brightness patterns couldn’t be explained by clouds or temperature. Instead, they pointed to dynamic carbon chemistry, such as rotating pockets of carbon monoxide or dioxide or changing chemical reactions.
Lead scientist Vos noted that these findings highlight how atmospheric conditions can vary across the object, adding complexity to understanding exoplanets as well.
Journal Reference:
Allison M. McCarthy, Johanna M. Vos, Philip S. Muirhead, Beth A. Biller et al. The JWST Weather Report from the Isolated Exoplanet Analog SIMP 0136+0933: Pressure-dependent Variability Driven by Multiple Mechanisms. The Astrophysical Journal Letters. DOI 10.3847/2041-8213/ad9eaf