Astronomers Uncover Potential Atmosphere on TRAPPIST-1e, 40 Light-Years Away

New research from the University of St Andrews has revealed that an Earth-sized exoplanet, known as TRAPPIST-1e, located approximately 40 light-years from Earth, may possess an atmosphere. The findings, published in the Astrophysical Journal Letters, suggest the possibility of oceans or an icy surface on this distant world, marking a significant advancement in the search for habitable conditions beyond our planet.

The study highlights the capabilities of the James Webb Space Telescope (JWST) in investigating the atmospheric composition of TRAPPIST-1e, the fourth planet in the red dwarf star system TRAPPIST-1. This project represents the first systematic search for an atmosphere and surface habitability around TRAPPIST-1e using the JWST. The planet orbits within the habitable zone of its star, which raises the intriguing possibility of liquid water if it has a suitable atmosphere.

Initial observations indicate several potential scenarios for TRAPPIST-1e, including the exciting prospect of an atmosphere. According to Dr. Ryan MacDonald, a lecturer in extrasolar planets in the School of Physics and Astronomy at the University of St Andrews, TRAPPIST-1e has long been considered a prime candidate for atmospheric study. He noted, “When our observations came down in 2023, we quickly realised that the system’s red dwarf star was contaminating our data in ways that made the search for an atmosphere extremely challenging.”

To overcome this hurdle, researchers utilized the powerful NIRSpec (Near-Infrared Spectrograph) instrument aboard the JWST to capture data as TRAPPIST-1e transited in front of its host star. As starlight passes through the planet’s atmosphere, it can be absorbed, resulting in changes to the light spectrum that reaches the JWST. This information enables astronomers to identify the chemical composition of the atmosphere. However, they also had to account for starspots, which are areas on the star’s surface affected by local magnetic fields, that could interfere with their observations.

The team dedicated over a year to correcting the data for the star’s contamination before focusing on the characteristics of TRAPPIST-1e’s atmosphere. Dr. MacDonald explained that their analysis revealed two possible scenarios. “The most exciting possibility is that TRAPPIST-1e could have a so-called secondary atmosphere containing heavy gases like nitrogen. But our initial observations cannot yet rule out a bare rock with no atmosphere,” he stated.

Further observations using the JWST are underway, which will enhance the search for an atmosphere around TRAPPIST-1e. With each additional transit observed, the clarity regarding the planet’s atmospheric contents will improve. Dr. MacDonald expressed optimism about the future of this research, mentioning, “In the coming years, we will go from four JWST observations of TRAPPIST-1e to nearly 20. We finally have the telescope and tools to search for habitable conditions in other star systems, which makes today one of the most exciting times for astronomy.”

This groundbreaking research not only contributes to our understanding of TRAPPIST-1e but also advances the broader quest for potentially habitable exoplanets outside our solar system. The findings underscore the importance of continued exploration and observation in uncovering the mysteries of distant worlds.