TRAPPIST-1 is a red dwarf star, which are way more common that sun-like stars. Perhaps the major difference between TRAPPIST-1 and our solar system is its central star. This data could be crucial in preventing future studies from jumping to conclusions about detecting a particular molecule in the exoplanet's atmosphere. However, what the scientists did find was a bunch of “ghost signals” in the starlight that appeared to come from dark and bright spots on the star itself.
In that light was the fingerprint of the molecules and atoms found within the planet’s atmosphere.
This study used a technique called transmission spectroscopy, using NIRISS to split the star’s light as it passed through the atmosphere of TRAPPIST-1 b. That’s a happy accident, but it also helps in the search for exoplanets. Scientists only know about the existence of planets around TRAPPIST-1 because they transit across the star as seen from the solar system.
