An article published in the journal “Nature” describes a research on two exoplanets of the TRAPPIST-1 system. A group of researchers led by Julien de Wit of the Massachusetts Institute of Technology in Cambridge, Massachusetts used the Hubble and Spitzer space telescopes to better examine two of the three exoplanets whose discovery was announced in May 2016.
The discovery of three exoplanets similar in size to the Earth orbiting an ultra-cool dwarf star raised great enthusiasm in the field of astronomy. The TRAPPIST (TRAnsiting Planets and PlanetesImals Small Telescope) telescope is a prototype for a more ambitious project and has already given a very interesting result showing that a star much smaller than the Sun can have potentially habitable planets.
The research on the TRAPPIST-1 exoplanets went on with other instruments. NASA’s Spitzer Space Telescope was used to obtain estimates on the exoplanets’ orbits and they allowed to predict for May 4, 2016 a double transit, meaning the simultaneous transit of two exoplanets in front of their stars. The researchers obtained the possibility of carrying out observations of that event with the Hubble Space Telescope, gaining important spectroscopic information.
The star TRAPPIST-1 emits radiation less intense than the Sun, more concentrated in the infrared than in the visible light range. This makes easier the analysis of its exoplanets’s atmosphere spectrum obtained during a transit. The results were really interesting, confirming the optimism concerning the two transiting exoplanets.
The light intensity of the star TRAPPIST-1 was diminished only in a limited range of wavelengths indicating that the atmosphere of the two exoplanets is compact and thin like that of the Earth and not extended like a mini-Neptune. In essence, it’s a confirmation that the two exoplanets called TRAPPIST-1b and 1c-TRAPPIST are rocky but that’s only the first step in the study of their atmospheres.
The main problem is figuring out what kind of atmosphere the two exoplanets could have. The TRAPPIST-1 system was likened to a miniature version of our solar system but in this case we have to consider extreme examples such as Mars’ thin atmosphere and Venus’ very thick one. In essence, this new research confirms that those are interesting exoplanets but it will be necessary to keep on studying them when new telescopes will enter service to get details on them.
