A team of astronomers from Université de Montréal has made significant strides in unraveling the mysteries of the TRAPPIST-1 exoplanetary system, which first made headlines in 2016 due to its potential as a future home for humans. The study highlighted the effectiveness of Canada's NIRISS instrument, demonstrating its capability to probe atmospheres on Earth-sized exoplanets with remarkable precision.
TRAPPIST-1, a star much cooler and smaller than our sun, has fascinated scientists and space enthusiasts alike since the discovery of its seven Earth-sized exoplanets. These planets, huddled closely around their star, raised hopes of finding habitable environments beyond our solar system.
Led by doctoral student Olivia Lim, researchers used the James Webb Space Telescope to observe TRAPPIST-1 b. These observations, part of a Canadian-led program, marked the first spectroscopic observations of any TRAPPIST-1 planet obtained by the JWST.
Transmission spectroscopy allowed astronomers to examine the unique atmospheric fingerprints of TRAPPIST-1 b. By analyzing the star's light as it passed through the exoplanet's atmosphere during a transit, researchers gained insights into the molecules and atoms present.
Astronomers discovered the critical role of stellar activity and contamination when studying exoplanets. Stellar contamination, caused by the star's features like dark spots and bright faculae, can affect measurements of an exoplanet's atmosphere.
Compelling evidence showed that stellar contamination can create "ghost signals," potentially misleading observers into detecting molecules that aren't present. Stellar flares, unpredictable events that make the star briefly brighter, also affected measurements.
Based on their JWST observations, researchers ruled out certain atmospheric compositions for TRAPPIST-1 b. While cloud-free, hydrogen-rich atmospheres were ruled out, thinner atmospheres like pure water, carbon dioxide, methane, or something akin to Titan's atmosphere remain possibilities.