Last week, astronomers gathered at the Space Telescope Science Institute, the operations center for the James Webb Space Telescope (JWST), in Baltimore, Maryland for a conference on the “First Science Results from JWST.” This meeting was meant to highlight all of the amazing science that JWST has done in only its first few months of science operations; science operations for JWST began in late June and the first images were released on July 12, 2022.
Early observations of the TRAPPIST-1 system, a highly anticipated target, and their results were revealed at this meeting. TRAPPIST-1 is a red dwarf star, a star much smaller and cooler than the Sun. It lies at a distance just 12 parsecs – or 39 light-years – from Earth. This star system was mapped out in great detail in 2017 and found to have seven exoplanets in orbit. All seven of the planets in this system (designated b through h, where b is the closest to the host star and h is farthest from the host star) are in or near the star’s habitable zone – the range of orbital distances in which liquid water may exist on the surface of a planet. Ever since its discovery, astronomers have been extremely excited about this system because it is a prime laboratory to study the conditions for habitability – or suitability for life – outside our Solar System.
JWST will be observing all seven planets in this system within its first year of science operations. The observations will provide clues to the atmospheres of the planets in orbit around TRAPPIST-1. To study the atmospheres of exoplanets, astronomers look at the light of the host star after it has passed through the atmosphere of the planet, filtering out certain wavelengths of light in an observed spectrum. The specific wavelengths where light is found to be missing will be characteristic of specific molecules, which would indicate the presence of these molecules in the exoplanet’s atmosphere. The molecules that make up an atmosphere can indicate how the planet evolved and whether it could have life on its surface.
The TRAPPIST-1 data are particularly hard to analyze because the exoplanets around it are so small, and thus the signal from their atmospheres are hard to tease out of the data, unlike the exoplanet WASP-39b, whose atmosphere was already studied in detail with the help of data obtained with JWST.
Preliminary results for the TRAPPIST-1 system will be released in an upcoming paper. Results for TRAPPIST-1g were shown at the conference. The data show that the planet likely does not have a hydrogen-rich atmosphere, and that the planet could have a denser atmosphere, which is composed of heavier molecules (such as carbon dioxide), or no atmosphere at all. More observations are needed to say definitively if it has an atmosphere, and if it does, what it is composed of.
More data on this system is coming soon, so look for results about this incredible planetary system in the near future!