Space

Seven Earth-sized planets found orbiting nearby red dwarf star

Seven Earth-sized planets foun...
Artists's impression of the TRAPPIST-1 solar system. TRAPPIST-1 now holds the record for the solar system with the most orbiting Earth-sized exoplanets
Artists's impression of the TRAPPIST-1 solar system. TRAPPIST-1 now holds the record for the solar system with the most orbiting Earth-sized exoplanets
View 5 Images
Artists's impression of the TRAPPIST-1 solar system. TRAPPIST-1 now holds the record for the solar system with the most orbiting Earth-sized exoplanets
1/5
Artists's impression of the TRAPPIST-1 solar system. TRAPPIST-1 now holds the record for the solar system with the most orbiting Earth-sized exoplanets
Size comparison between Jupiter, her moons, the TRAPPIST-1 system,  and the other planets that comprise our solar system
2/5
Size comparison between Jupiter, her moons, the TRAPPIST-1 system,  and the other planets that comprise our solar system
Orbital comparison between the TRAPPIST-1 system, the moons of Jupiter, and the orbits of the planets that make up our home solar system
3/5
Orbital comparison between the TRAPPIST-1 system, the moons of Jupiter, and the orbits of the planets that make up our home solar system
Orbital comparison between the TRAPPIST-1 system, the moons of Jupiter, and the orbit of Mercury relative to our Sun
4/5
Orbital comparison between the TRAPPIST-1 system, the moons of Jupiter, and the orbit of Mercury relative to our Sun
Diagram displaying the orbits of the TRAPPIST-1 solar system (with the shaded area representing the star's habitable zone)
5/5
Diagram displaying the orbits of the TRAPPIST-1 solar system (with the shaded area representing the star's habitable zone)

An international team of astronomers has announced the discovery of seven Earth-sized exoplanets in orbit around a nearby ultracool red dwarf star. Whilst all the exoplanets discovered around the red dwarf, known as TRAPPIST-1, are capable of hosting liquid water on their surfaces, three are in orbit in what is known as a star's habitable zone, making them an attractive prospect for scientists searching for life outside of our solar system.

TRAPPIST-1 is only a little larger than the planet Jupiter, with a mass of only eight percent of our Sun. The eight exoplanets were confirmed following an intensive imaging campaign undertaken by a host of observatories, including the European Southern Observatory's Very Large Telescope, located at the Paranal Observatory in Chile, and NASA's orbital Spitzer Space Telescope.

The team was able to deduce the number of exoplanets, as well as certain characteristics of these alien worlds such as their size, orbit, and composition, by identifying dips in the perceived light output of TRAPPIST-1 as the planets passed between Earth and the star, blocking a portion of its light.

Size comparison between Jupiter, her moons, the TRAPPIST-1 system,  and the other planets that comprise our solar system
Size comparison between Jupiter, her moons, the TRAPPIST-1 system,  and the other planets that comprise our solar system

Due to its diminutive size, TRAPPIST-1 appears very dim in the sky, despite lying only 40 light-years distant from Earth – relatively close in astronomical terms.

"The energy output from dwarf stars like TRAPPIST-1 is much weaker than that of our Sun," comments Study co-author Amaury Triaud. "Planets would need to be in far closer orbits than we see in the Solar System if there is to be surface water. Fortunately, it seems that this kind of compact configuration is just what we see around TRAPPIST-1!"

The planets have been named TRAPPIST-1b, c, d, e, f, g, and h. TRAPPIST-1b represents the planet closest to the red dwarf, with h being the most remote. The TRAPPIST-1 solar system is far more cramped than our own, with each of the seven worlds orbiting closer to their star than Mercury does to the Sun.

According to density measurements taken by the team, it is likely that the innermost six exoplanets have a rocky composition. Climate models suggest that TRAPPIST-1b, c and d are likely too hot to maintain liquid water across all but a fraction of their surfaces.

Orbital comparison between the TRAPPIST-1 system, the moons of Jupiter, and the orbits of the planets that make up our home solar system
Orbital comparison between the TRAPPIST-1 system, the moons of Jupiter, and the orbits of the planets that make up our home solar system

The seventh planet in the system, TRAPPIST-1h, is likewise considered unlikely to host liquid water. However, the team has not ruled out the possibility of liquid water on the outermost planet, as it is possible that a phenomenon known as tidal heating, which is thought to be the driving force behind the eruptions taking place on the Jovian moon Io, could be warming the exoplanet.

However, without question the most exciting of the exoplanets are TRAPPIST-1e, f, and g, which reside within the red dwarf's habitable zone (HZ). It is possible that the rocky planets within this region could support oceans of liquid water, making them an attractive breeding ground for life outside of our solar system.

The TRAPPIST-1 solar system is currently being targeted for follow up observations by the venerable Hubble Space Telescope, which will attempt to discover whether any of the newly confirmed worlds play host to an atmosphere. The star will also be a high-priority target for the next generation of planet hunting observatories, including the ESO's European Extremely Large Telescope, and the NASA/ESA/CSA James Webb Space Telescope.

The following NASA video offers a look at what life might be like on a TRAPPIST-1 planet.

TRAPPIST-1: Weirdest habitable worlds

Source: ESO

4 comments
Nairda
A few interesting prospects. First, the close distance between each planet might serve to cause tidal movements on the planets within the G zone. This is beneficial for evolution of life. Secondly, planets like T 1 that are locked to a permanent hot and cold side would offer a very wide range of temperatures for life to take hold in most optimal location. The tides would also help to cause the hot to cold band to be wider. And for a species to evolve on this system would also be an advantage as they would have easy access to neighbor planets for resource extension, where as we have to travel quite far to mine our planets.
Neil Farbstein
the probability of life in the universe has gone up
josrun
no body challenge the scientist by asking them the fact from fiction. We cant escape the planet so why we are interested by whats happening at nearest 40 light years distant from Earth. We still imagining profoundly that one day we will be out there instead concentrating our effort to eradicate the obstacle first . that will be a gigantic achievement.
Grumpyrelic
Hokay... So the "Trappists" are now at roughly 1977 in our TV and radio transmissions to them. They would know of WWII, the atom bomb, Korean war, the cold war, Cuban crisis, etc. Bet they can't wait to hear Chicken Little blame "global warming" on a building block of life - CO2. Does anyone really think that they would respond to peace and harmony overtures from us?