Recent observations from the James Webb Space Telescope (JWST) have provided new insights into the atmospheric conditions of the exoplanet TRAPPIST-1 b. Measurements taken during the secondary eclipse at wavelengths of 12.8 and 15 microns indicate a remarkably bright dayside, which suggests a lack of significant atmospheric presence. Previous studies utilizing one-dimensional (1D) atmospheric models also indicated that carbon dioxide-rich atmospheres were unlikely. However, a broader range of atmospheric possibilities has yet to be fully explored.
In a new study led by researcher Alice Maurel and her colleagues, researchers employed both 1D radiative-convective models and a more advanced three-dimensional global climate model (GCM) to assess a variety of atmospheric compositions and surface pressures. The findings from these simulations were contrasted with existing emission observations, particularly the full thermal phase curve of TRAPPIST-1 b, which was recently observed at 15 microns.
The team focused on identifying atmospheres that could account for the dayside emissions observed during the secondary eclipse. They identified several atmospheric families that align closely with the eclipse observations, with some scenarios featuring flat phase curves that can be ruled out based on the data. Notably, thin atmospheres composed mainly of nitrogen and carbon dioxide were among those that produced results consistent with the observed thermal behavior of the planet.
The research also highlighted important three-dimensional effects that previous one-dimensional studies could not predict, such as atmospheric redistribution efficiency and potential atmospheric collapse. Current observational data align most closely with the hypothesis that TRAPPIST-1 b is largely airless, which remains the most plausible scenario. Alternatively, the study also suggests the possibility of a thin, carbon dioxide-poor residual atmosphere.
While the study provides valuable insights, it emphasizes the complexity of drawing conclusions about the presence of an atmosphere based solely on single photometric measurements. The research team cautions that various atmospheric scenarios can yield high eclipse depths at 15 microns, making it essential to consider multiple observational data points for accurate assessments.
This work, accepted for publication in Astronomy and Astrophysics, spans 26 pages and includes 24 figures detailing the diverse atmospheric scenarios examined. The findings mark a significant advancement in understanding the environmental conditions of TRAPPIST-1 b and contribute to the ongoing exploration of potentially habitable worlds beyond our solar system.
Researchers involved in this study include Martin Turbet, Elsa Ducrot, Jérémy Leconte, and others, who collectively aim to deepen the understanding of exoplanetary atmospheres through innovative modeling techniques.
