Earth’s “twin” exoplanet just 72 light-years away has been discovered
It’s the same size
Astronomers have discovered an Earth-sized exoplanet in close orbit around a small star. K2-415b ‘s similarities and differences to Earth will give us more insight into how Earth-like planets form and evolve in different ways in star systems different from our own.
The minor planets around M-type red dwarfs are a good laboratory to explore the atmospheric diversity of rocky planets and the conditions under which a habitable planet can exist. Being one of the lowest mass stars to host an Earth-sized planet, K2-415 will be an interesting target for further observations. – Teruyuki Hirano, Astrobiology Center, Japan
Since Earth is the only planet known to have life so far, it makes sense to look for life on planets similar to Earth in size, composition, temperature, mass, and planetary system architecture. They are the best candidates for having an atmosphere. As the exoplanet passes in front of the star, some of the star’s light passes through the atmosphere, with some wavelengths of the spectrum being absorbed or amplified by the atmospheric elements.
But small Earth-sized exoplanets are more difficult to detect. Within 100 light years of Earth, only 14 exoplanets with a diameter 1.25 times that of Earth have been detected orbiting a red dwarf. Half of them are in the TRAPPIST-1 system.
The exoplanet K2-415b is 1,015 times the diameter of Earth, with its star having only 16% the mass of the Sun. Beyond the size, however, the similarities with Earth are not many. The mass of K2-415b is three times that of Earth, which means it is much denser. Thus, it is much closer to the star, with a complete revolution around it taking just four days. Because the red dwarf is much smaller than the Sun, however, K2-415b is within the habitable zone and likely has an atmosphere. It is also possible that the K2-415 system has more planets in orbit, raising the question of the existence of another planet in the habitable zone.
The research is available on arXiv and will soon be published in The Astronomical Journal .
