Groundbreaking new research from the University of St Andrews has identified signs of a potential atmosphere surrounding an Earth-sized exoplanet located 40 light years away, raising exciting possibilities for habitable conditions beyond our solar system.
In two separate papers published today (Monday 8th September) in the Astrophysical Journal Letters, researchers have shed new light on an exoplanet, TRAPPIST-1e, where liquid water, in the form of a global ocean or icy expanse, might exist on its surface. That would only be possible if an atmosphere is present, a mystery the scientists are one step closer to solving using the world's largest telescope in space, the James Webb Space Telescope (JWST).
An Artists impression of TRAPPIST 1e silhouetted as it passes in front of its flaring host star. Credit: NASA, ESA, CSA, J. Olmsted (STScI)
In a major international project, researchers have conducted the first search for an atmosphere and surface habitability of the exoplanet TRAPPIST-1e with the JWST, the fourth planet in the red dwarf star system TRAPPIST-1, which orbits firmly within the star's habitable zone. Planet 1e is of particular interest because the presence of liquid water is theoretically viable, but only if the planet has an atmosphere.
The initial results indicate several potential scenarios, including the possibility of an atmosphere on TRAPPIST-1e.
These findings are a significant moment in the search for habitable conditions beyond Earth.
Dr Ryan MacDonald, Lecturer in Extrasolar Planets in the School of Physics and Astronomy at the University of St Andrews, said: "TRAPPIST-1e has long been considered one of the best habitable zone planets to search for an atmosphere. But 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."
Dr Ryan MacDonald
The researchers aimed the JWST's powerful NIRSpec (Near-Infrared Spectrograph) instrument at the system as planet 1e passed in front of its star. Starlight passing through the planet's atmosphere, if there is one, will be partially absorbed and the corresponding changes in the light spectrum that reaches the JWST tell astronomers what chemicals are found there. But astronomers must also carefully account for starspots, spots created by local magnetic fields on the surfaces of stars, from the red dwarf star.
The team spent over a year carefully correcting the data for the star's contamination before they could zero in on the planet's atmosphere.
Dr MacDonald, who contributed to the analysis of TRAPPIST-1e's spectrum, added: "We are seeing two possible explanations. 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."
Credit: NASA, ESA, CSA, J. Olmsted (STScI)
The researchers are now obtaining further JWST observations of TRAPPIST-1e to enable a deeper search for an atmosphere.
With each additional transit, the atmospheric contents become clearer.
Dr MacDonald, continued: "In the coming years we will go from four JWST observations of TRAPPIST-1e to nearly twenty, 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."
The JWST is the world's premier space science observatory, capable of observing distant worlds and stars, and probing the mysterious structures of our universe. It is an international programme led by NASA, the European Space Agency, and the Canadian Space Agency.
The project is part of the JWST-TST DREAMS (Deep Reconnaissance of Exoplanet Atmospheres through Multi-instrument Spectroscopy) programme, led by Prof Nikole Lewis, Associate Professor of Astronomy at Cornell University in the US city of Ithaca, New York. This international project involves more than 30 scientists from the UK, USA, and India.
Category Research
