It’s you and me, Kepler-442b.
What does it take for an alien exoplanet to harbor life as we know it? A lot, in the end.
Despite an article from last year claiming that there could be 300 million planets in our galaxy that are “potentially habitable,” new research published in the Monthly notices from the Royal Astronomical Society confuses this point of view.
Suggesting that Earth-like conditions on potentially habitable planets could be much rarer than previously thought, this new analysis of known exoplanets focuses on photosynthesis.
4,422 exoplanets have been discovered to date by astronomers, but only a handful are considered potentially habitable.
Photosynthesis is how plants use sunlight, water, and carbon dioxide to create oxygen and energy.
Since photosynthesis played a critical role in creating complex biospheres of the type found on Earth for an exoplanet to be potentially habitable, this therefore means that it would develop an oxygen-based atmosphere.
The James Webb Space Telescope (JWST), slated for launch later this year, will be able to study the atmosphere of exoplanets as they pass through their stars. The light passing through their atmosphere will reveal the gases they contain.
However, photosynthesis requires liquid water. Only exoplanets at the right temperature, neither too hot nor too cold, could harbor such a thing on their surface.
So how many Earth-sized rock exoplanets are in this so-called “golden loop area? ”
Not a lot, this research suggests.
In fact, even in the handful of known rocky and potentially habitable exoplanets, none have the theoretical conditions to maintain an Earth-like biosphere fueled by photosynthesis.
It’s not all bad news.
The study, which investigated the amount of radiation (sun) that each promising exoplanet receives from its star, reveals a planet that is about to receive enough sun to support a large biosphere that could be detected by JWST – Kepler- 442b.
What we know about Kepler-442b
A rocky planet about twice the mass of Earth, Kepler-443b orbits a moderately hot orange dwarf star about 1120 light years away in the constellation Lyra.
Its existence was announced in 2015 after being discovered by the Kepler Space Telescope passing through its mother star. The telescope ceased to function in 2018.
Also called KOI-4742.01, this exoplanet is about half the distance from its star as Earth is from the Sun. Kepler-443 orbit takes 112 days.
However, it is a “super-Earth,” which, despite its name, does not look exactly like Earth.
The study concludes that stars at about half the temperature of our Sun cannot support Earth-like biospheres because they do not provide enough energy in the correct wavelength range.
This doesn’t mean that photosynthesis would be possible, but there wouldn’t be enough plant life on the planet to support an Earth-like biosphere.
This is a big blow to the search for life in the galaxy since 70% of the stars in the Milky Way are dark red dwarf stars (also known as M dwarfs), none of which – this study suggests – gives their planets enough. of sunlight for photosynthesis to occur.
Worse, stars hotter and brighter than our Sun could, in theory, produce more photosynthesis, but these stars don’t exist long enough for complex life to evolve, the study suggests.
“Since red dwarfs are by far the most common type of star in our galaxy, this result indicates that Earth-like conditions on other planets may be much less common than we might hope. Said the lead author, Professor Giovanni Covone of the University of Naples. “This study places strong constraints on the parameter space for complex life, so it unfortunately seems that the ‘sweet spot’ for hosting a rich Earth-like biosphere is not that wide. ”
I wish you clear skies and big eyes.