We discovered an exoplanet that’s nearly exactly the same size as the Earth, orbiting a tiny star not far away.
Its name is K2-415b, and its similarities (and differences) to our own home world may shed some light on how earth-like planets form and develop in systems very different from our individual.
“Small planets close to M dwarfs are a great laboratory to examine the atmospheric diversity of rocky planets and the conditions at which a habitable terrestrial world is able to exist,” writes an international team of astronomers led by Teruyuki Hirano of the Astrobiology Center in Japan.
Becoming a one of the lowest mass stars recognized to hold an earth-sized transiting planet, K2-415 is going to be an interesting target for more follow up observations, including more radial velocity monitoring and transit spectroscopy.
Study was approved for publication in the Astronomical Journal and is accessible on the arXiv preprint server.
The Milky Way galaxy is a great site with many intriguing worlds, but at this point it has been evasive on one of the leading issues ever requested by mankind: Just why is it we are here? And why this planet? can there be someplace else on the planet where life could exist?
Since Earth could be the only place in the Universe where we know for a fact life has emerged, one of the tools which could help provide solutions is a population of exoplanets which can be much like Earth. Very similar in dimensions, structure, temperature, weight. maybe even planetary system design.
The best population of exoplanets to begin the research are little, earth-sized worlds orbiting small stars fairly close in such a manner that they transit or pass between us and the star. That is because they are the ideal candidates for defining an atmosphere.
As the exoplanet passes near the star, a portion of the light from the star will pass through an atmosphere, with several wavelengths of the spectrum being absorbed by elements in the atmosphere or amplified.
The habitable environment zone is much closer to the star around smaller, dimmer, cooler stars, like red dwarfs, than around a bright star such asRB_IN our Sun. This shorter orbital period means that many transits can be captured and stacked to maximize the spectrum information. And naturally, closer stars are going to appear brighter, which will make such observations less difficult.
However, small exoplanets tend to be harder to locate compared to big ones. Within 100 light years of the Solar System, just 14 exoplanets smaller than 1.25 times the radius of Earth have been identified orbiting red dwarf stars – which includes all 7 worlds in the TRAPPIST 1 system.
In this case, there’re no too many data points, and Hirano and his colleagues appear to have found a doozy. The exoplanet K2 415b is 1.015 times the radius of the Earth, orbiting among the smallest red dwarf stars ever found to host an earth-sized planet. The star, K2-415, is just 16 % of the mass of the Sun.
The exoplanet was spotted for the very first time in 2017 in data from the now retired Kepler Planet Hunting telescope, and it additionally showed up in data from Kepler’s successor TESS.
Then the researchers had taken infrared measurements to find out if they could detect a slight wobble “in the star’s motion as it is getting ever-so slightly twitched by the gravity of the exoplanet.
This considerable amount of information revealed the presence of a world and its qualities. The amount of light obstructed during exoplanet transits can be used to calculate the planetary radius. Its mass is determined by the level of squatness.
These two parameters may be combined to compute density of the exoplanet. Moreover, the regularity of transits reveals the orbital period of the exoplanet.
And this is where K2 415b is different from the Earth seriously. Although approximately the size of an Earth, the exoplanet is much larger, more or less three times the mass of the Earth. This additionally means that K2-415b is much denser compared to Earth.
Plus it’s a great deal closer to its peak. It features an orbital period of only 4 days. The habitable zone of a white dwarf star may be much nearer to the Sun’s habitable zone, with orbits measurable in days rather than months, but still way too close for comfort, even for a red dwarf star.
Just a little though. The K2 415b is located just inside the rim of the habitable area of K2 415. That might mean that there’s still atmosphere to investigate. Venus is simply within the habitable area in the Solar System, and its atmosphere is a dense and fascinating horror show.
It’s additionally likely that K2-415 is a multi-planet system. This increases the possibility of a currently undetected exoplanet in the habitable zone of the star.
So, we are not going to discover signs of life on K2-415b. The system, however, represents an excellent target for atmospheric characterization of exoplanets and follow up surveys searching for hidden, potentially life- threatening worlds.
The research has been accepted for publication in The Astronomical Journal, and is available on arXiv.
