Astronomers using the NASA/ESA/CSA James Webb Space Telescope have made new observations about the atmosphere of a rapidly rotating, free-floating planetary-mass object called SIMP J013656.5+093347. The object, located 20 light-years from Earth, has a mass of 13 Jupiter masses and is believed to be a brown dwarf.
The telescope’s NIRSpec instrument captured thousands of spectra of the object over three hours, revealing patchy cloud layers that rotate in and out of view and evolve over time. The MIRI instrument collected hundreds of measurements of light from different wavelengths, showing the change in brightness of specific colors as the object rotated into view.
Researchers noticed distinct light-curve shapes, with some wavelengths growing brighter while others became dimmer or unchanged. Different factors are affecting these variations, including clouds, temperature, and atmospheric carbon chemistry.
Atmospheric models showed that certain wavelengths originated from different depths in the atmosphere, confirming that similar light curves were caused by the same mechanism. One group of wavelengths came from patchy clouds made of iron particles, while another group came from higher clouds thought to be made of silicate minerals.
The variations are related to cloud layers and temperature. Bright hot spots could be due to auroras or upwelling of hot gas from deeper in the atmosphere. Some light curves showed no explanation by clouds or temperature but were instead linked to changes in atmospheric carbon chemistry.
These findings provide valuable insights into the behavior of a free-floating object, demonstrating that it’s possible to study an exoplanet with only one measurement. The results appear in the Astrophysical Journal Letters and offer new perspectives on the properties of planetary-mass objects like SIMP J013656.
Source: https://www.sci.news/astronomy/exoplanet-cloud-layers-hot-spots-chemistry-13714.html