Proxima b, a potentially habitable rocky exoplanet
Proxima Centauri, the star closest to the Sun, has a planet. Named Proxima b, this rocky exoplanet is comparable in size to Earth and has a surface temperature compatible with the presence of liquid water, meaning it could well be habitable... This major discovery was published on August 25, 2016, in Nature by an international team of researchers including Julien Morin from the Montpellier Universe and Particle Laboratory (CNRS/University of Montpellier).
It is the closest exoplanet ever discovered: Proxima b orbits Proxima Centauri, the closest star to the Sun, at "only" 4.2 light-years away. This discovery marks a major turning point in research: Proxima b could well be conducive to life... The exoplanet is most likely rocky, like our planet, and is located 7 million kilometers from Proxima Centauri, 20 times closer than Earth is to the Sun. Too close? No, because Proxima Centauri, a simple red dwarf, is much less bright than the Sun. Proxima b is therefore well within the habitable zone and its temperature could allow liquid water to exist on its surface.
Is Proxima b a small twin of planet Earth? More like a distant cousin, according to research conducted by scientists. Two teams, mainly French, have shown that although Proxima b could potentially support life, it cannot be considered a twin of Earth. The history of Proxima b and its star has been radically different from that of Earth and the Sun. The formation of Proxima b, its irradiation by Proxima Centauri, and the tidal forces it undergoes, which affect its internal structure and rotation, have no equivalent in the history of our planet.
Detections of rocky planets orbiting active dwarf stars are expected to increase in the coming years with the commissioning of dedicated instruments such as SPIRou. This international near-infrared spectropolarimeter, developed by France, will be commissioned in 2017 at the Canada France Hawaii Telescope (CFHT) located at the summit of Mauna Kea volcano in Hawaii. The dawn of a new era in space exploration.
Illustration: This artist's impression shows the planet Proxima b orbiting the red dwarf Proxima Centauri, the closest star to the Solar System. The Alpha Centauri AB binary star system appears in the upper right corner of the image, between the planet and the star Proxima. Proxima b has a mass slightly greater than that of Earth and orbits Proxima Centauri within the star's habitable zone, meaning that its surface temperature is compatible with the presence of liquid water.
References: A terrestrial planet candidate in a temperate orbit around Proxima Centauri, by G. Anglada-Escudé et al., August 25, 2016, Nature.