Astronomers confirm details of TRAPPIST-1h exoplanet

Details about TRAPPIST-1h, the outermost and least understood planet of the TRAPPIST-1 system, were recently confirmed by scientists using NASA’s Kepler space telescope. Astronomers previously feared they were just seeing what they wanted to see in matter of the planet’s orbit, but now they have a confirmation.

The TRAPPIST-1 system is home to seven Earth-size planets, three of which orbit in their star’s habitable zone. Now, scientists from the University of Washington have used data from the Kepler spacecraft to confirm that TRAPPIST-1h – the exoplanet furthest from TRAPPIST-1 – orbits its star every 19 days, according to NASA’s Jet Propulsion Laboratory.

At six million miles from its cool dwarf star, TRAPPIST-1h is located beyond the outer edge of the habitable zone and is likely too cold for life as we know it. The amount of energy (per unit area) the planet receives from its star is comparable to what the dwarf planet Ceres, located in the asteroid belt between Mars and Jupiter, gets from our sun.

The team recognised a mathematical pattern – called an orbital resonance – in the frequency at which each of the six innermost planets orbits their star. The work to confirm TRAPPIST-1h’s orbital period began immediately after raw, uncalibrated data was released to the scientific community to begin follow-up studies, back in March. Scientists from around the world took to social media to share in real-time the new information gleaned about the star’s behaviour and its brood of planets. Within two hours of the data release, the team confirmed its prediction of a 19-day orbital period.

TRAPPIST-1’s seven-planet chain of resonances established a record among known planetary systems, the previous holders being the systems Kepler-80 and Kepler-223, each with four resonant planets.

“It’s incredibly exciting that we’re learning more about this planetary system elsewhere, especially about planet h, which we barely had information on until now. This finding is a great example of how the scientific community is unleashing the power of complementary data from our different missions to make such fascinating discoveries,” Thomas Zurbuchen, associate administrator of NASA’s Science Mission Directorate at Headquarters in Washington, said.

“Nature usually surprises us at every turn, but, in this case, theory and observation matched perfectly,” Rodrigo Luger, a doctoral student at UW in Seattle, added.

TRAPPIST-1 is only eight percent the mass of our sun, making it a cooler and less luminous star. It’s home to seven Earth-size planets, three of which orbit in their star’s habitable zone — the range of distances from a star where liquid water could pool on the surface of a rocky planet. The system is located about 40 light-years away in the constellation of Aquarius. The star is estimated to be between 3 billion and 8 billion years old.

Scientists announced that the system has seven Earth-sized planets in February 2017. NASA’s Spitzer Space Telescope, the TRAPPIST (Transiting Planets and Planetesimals Small Telescope) in Chile and other ground-based telescopes were used to detect and characterise the planets.