Exoplanet Discovery: TRAPPIST-1h Planet Orbit Discovered, Is It Habitable?
Scientists have developed a better understanding of the TRAPPIST-1h, the farthest and most mysterious planet in the recent exoplanet discovery that is TRAPPIST-1 system.
First revealed in February, the system, believed to be 3- to 8-billion years old, consists of seven Earth-sized planets orbiting around TRAPPIST-1, a star only eight-percent the size of the sun making it much colder and less bright.
Three of the exoplanets in the system, which is 40 light-years away in the constellation of Aquarius, hosts orbit within the habitable zone, but the one that mystified astronomers is the TRAPPIST-1h, the planet farthest away from the star.
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Scientists from University of Washington (UW) made use of data gathered by the National Aeronautics and Space Administration's (NASA) Kepler Space Telescope to learn more about the outermost exoplanet.
The information helped them confirm that TRAPPIST-1h orbits its star every 19 days. It sits six millions miles from it, putting it beyond the habitable zone.
This means that the TRAPPIST-1h will be too cold to sustain life. To put things into perspective, NASA says that the amount of energy (per unit area) the exoplanet gets from the dwarf star is like that of what the dwarf planet Ceres, located in the asteroid belt between Mars and Jupiter, gets from the sun.
Before the information was confirmed by the Kepler data, the University of Washington (UW) astronomers already managed to figure out the orbital period of the TRAPPIST-1h by studying the orbital velocities of the innermost planets.
The data from the Spitzer Space Telescope, which paved the way for the exoplanet discovery and the characterization of the planets, was also used by Luger's team to pinpoint the orbital dissonance of the TRAPPIST-1 planets.
Orbital dissonance, according to NASA, is the mathematical pattern in the frequency at which each of the six innermost planets orbits their star.
The "complex but predictable pattern" takes place once the planets "exert a regular, periodic gravitational tug on each other as they orbit their star."
The team determined six possible resonant periods for the seventh exoplanet that are unlikely to break off the stability of the system, but only one was not ruled out by additional data from Kepler.
Luger explained that this data shows that the orbital relationships were established during the early life of the exoplanet system, during the planet formation process.
"It really pleased me that TRAPPIST-1h was exactly where our team predicted it to be," UW doctoral student Rodrigo Luger and lead author of the study published in the journal Nature Astronomy, said.
"It had me worried for a while that we were seeing what we wanted to see — after all, things are almost never exactly what you expect them to be in this field. Nature usually surprises us at every turn, but, in this case, theory and observation matched perfectly," he went on to say.
