What would an Earth-like planet look like in our neighboring cosmic system Alpha Centauri? Thanks to the close position of the star system, about 4 light years away from Earth, astronomers have excellent conditions to detect new exoplanets in our cosmic neighbor.
The James Webb Space Telescope (JWST), launched in December 2021, will be responsible for detecting the atmospheres of rocky exoplanets transiting in front of M dwarfs, stars that are fainter than the Sun, orbiting within the “habitable zone”. “. For its part, the Extremely Large Telescope (ELT), currently under construction in Chile, will be configured to obtain direct images of rocky exoplanets around nearby Sun-like stars. And, looking a little further, the Large Interferometer for Exoplanets (LIFE), will target rocky habitable zone exoplanets and their atmospheres.
These are exciting times for exoplanet research
Meanwhile, an international team of scientists led by academics at ETH Zurich have been creative in trying to imagine the properties of a potential Earth-sized planet in the habitable zone of the system made up of three stars, Alpha Centauri A and B (similar to the Sun) and Proxima Centauri (or Alpha Centauri C) , a significantly more distant red dwarf (4.22 light years away) that has three planets; evidence for the latter was only recently discovered and would be a world barely a quarter of the mass of Earth.
Regarding Proxima Centauri, this red dwarf was discovered in 1915 ; it is seven times smaller than the Sun and thanks to the most recent observations of the European Southern Observatory (ESO), the first worlds orbiting around it were identified.
What would this planet be like?
Modeling hypothetical planets is indispensable for understanding rocky habitable zone exoplanets and for guiding future observations and instrumentation development. Of what elements would a hypothetical rocky planet in the habitable zone of this system be composed? They have baptized it α-Cen-Earth’ (Earth of Alpha Centauri),
Its modeling is based on the spectroscopically measured chemical compositions of a Centauri A and a Centauri B planet, for which a large amount of information is available for both rock-forming elements (such as iron, magnesium, and silicon) and volatile elements (including hydrogen, carbon, and oxygen). Based on these data, they projected its possible composition: the planet would be geochemically similar to Earth, with a mantle dominated by silicates, but enriched with carboniferous species such as graphite and diamond. This could be important for the possibility of life, since it would have the ability to store water just like the Earth.
“The detailed analysis offers a new approach to investigating what we can expect from Earth-size planets in the habitable zones of the solar neighborhood,” comment the authors who publish their study in The Astrophysical Journal.
It would not be a perfect twin of the Earth, it is clear. It would possess, experts predict, a larger iron core and less geological activity (probably without plate tectonics). However, one of his curiosities would be that the primitive atmosphere of the hypothetical planet could have been dominated by carbon dioxide, methane and water, similar to that of the Earth during the Archean eon period, between 4,000 and 2,500 million years ago. , when the first form of life arose on our planet. Certainly exciting similarities.
A future of brilliant discoveries awaits us
Thanks to the new observing power that we can expect in the coming years, there is a legitimate hope that one or more exoplanets orbiting a Centauri A/B will join the nearly 5,000 exoplanets that have been discovered since 1995. From 2022 and until 2035, Alpha Centauri A and B are visually far enough apart for telescopes to find them.
Referencia: Haiyang S. Wang et al. A Model Earth-sized Planet in the Habitable Zone of α Centauri A/B. Published 2022 March 10 • © 2022.The American Astronomical Society.
The Astrophysical Journal, Volume 927, Number 2 iopscience.iop.org/article/10.3847/1538-4357/ac4e8c
