E Miss lurks close to home! A planet orbiting the star nearest the solar system, Proxima Centauri, and potentially habitable, has been discovered by scientists, including a CNRS in Montpellier.
Named Proxima b This probably rocky planet, with a mass similar to that of Earth, is located in an area called ” living “or” tempered “, in theory allowing the presence of liquid water on the surface, a necessary condition for life, according to researchers who published their work Wednesday, August 24 in the journal Nature.
due to its proximity, “Proxima b could be the first exoplanet to be visited by a probe if man manages one day to develop the necessary technologies,” said one of the authors of the study, Julien Morin, the Laboratory Universe and Particles CNRS / University of Montpellier.
Invisible to the naked eye
Since 1995, thousands exoplanets (planets outside our solar system) have been discovered, tens appearing potentially habitable. But they are far away. The youngest, however, is almost under our noses, across the Universe. It revolves around Proxima Centauri, a well-known red dwarf astronomers and science fiction fans, which is only 4.2 light years from the sun. A light year corresponds to 9.461 billion kilometers.
Proxima Centauri is too low light to be visible to the naked eye. An international team of astronomers, coordinated by Guillem Anglada-Escudé from Queen Mary University of London, discovered Proxima b through research campaign over two years, which intensified in the first half. It mobilized including the HARPS spectrograph installed on the ESO telescope (European Southern Observatory) in Chile.
The researchers also relied on a series of measurements taken between 2000 and 2014 on telescopes the O. Astronomers have identified Proxima b managing to detect very small oscillation of the star caused by the gravitational attraction generated by the small planet in orbit. At regular intervals, Proxima Centauri is approaching us and it recedes at a rate close to 5 km / hour, not like a human.
An intense radiation
Researchers have taken care to ensure that this phenomenon could not be related to magnetic activity of the star. “The signal is periodic, it is repeated,” said Mr. Anglada-Escudé during a press briefing. “Statistically, there is no doubt,” said he said. “We found a planet around Alpha Centauri”.
b puts Proxima 11.2 days to circle the sun. It is distant only about 7 million kilometers from its star (or 5% of the Earth-Sun distance) but it is 700 times less luminous than the sun. This allows Proxima b “to be in the habitable zone around its star, the temperature at the surface for considering the presence of liquid water” surface, said ESO.
“A rather exotic environment”
scientists estimate that the mass of the planet Proxima b is at least 1.3 times that of Earth. “This is probably a rocky planet and not a gas planet,” said Pedro Amado, the Andalusian Astrophysics Institute. However, Proxima b is probably quite different from the Earth.
“It is clearly in a rather exotic environment compared to that of our planet,” points Julien Morin. “The new planet orbiting very close to its star, we believe that the tides force tend to synchronize the rotation of the planet itself with its revolution around its star,” he says. “It shows without doubt always the same face to its star as the Moon always shows the same face.”
Are there any atmosphere?
the question of whether the planet has an atmosphere still is crucial in determining the chances of harboring some form of life. With an atmosphere, “it is plausible that the temperatures are in the range of – 30 degrees Celsius on the side in shadow and + 30 degrees to the side exposed to light,” says Anglada-Escudé <. / p>
But there are quite a downside: due to its proximity to its star that is quite active, Proxima b undergoes many more X and extreme UV radiation that Earth receives from Sun (about 100 times, according to researchers). And on Earth, the atmosphere and the presence of a magnetic field protect us from radiation and solar particles.
“All forms of life “might be possible
the exoplanet Proxima b, could swell the ranks of dozens of other planets located in the” habitable zones “where” all forms of life are possible, “said Jean Schneider , CNRS astrophysicist at the Paris Observatory.
What is an exoplanet? An exoplanet is a planet orbiting a star outside the solar system. An exoplanet is not more than a few tens of times the mass of Jupiter, the largest planet in our solar system. To date, we have found nearly 500 exoplanets proven over 3 several thousand candidates that require additional analysis. Proxima b, if its existence is confirmed, is more interesting than the others because it is around the nearest star to us and lets hope to go there one day.
How do you detect? There are three techniques. The most obvious is to take the exoplanet photos. The second method is the one used for Proxima b. If the movement of a star is disrupted then it is that there is a planet that disturbs under the effect of the laws of gravitation. It was the most cost-effective technique until 2010. Then the American Kepler telescope was launched. It uses a different method: that transits. If the orbit of the planet is tilted correctly in the sky in relation to us, the planet regularly passes in front of its star. It then produces a small eclipse, also known as a transit. With this method, Kepler has detected several thousand planets.
Is there a chance of finding life? Of the thousands of confirmed exoplanets, only a few dozen, like Proxima b in a habitable zone , ie the area around the star where a planet has a temperature compatible with the presence of water in the liquid state. The temperature is a sufficient criterion for it to be habitable, but that does not mean it to be inhabited, there is really biological organisms. But from there, all forms of life are possible.
The range is extremely wide. the atmosphere of the properties may also play a role. Be extremely open about what we call life. Already on Earth, there is great biodiversity. Life fits almost all circumstances. We found biological organisms in Antarctica background, bacteria survive in nuclear power plants, while on other planets, there may be many more.
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