CARMENES discovers two potentially habitable planets around a small star in the Solar neighborhood


Infographic of the habitable area of different stars, including the Star of Teegarden. © Chester Harmen, Planets: PHL@UPR Arecibo, NASA/JPL. 

An international study by the CARMENES consortium, of which the Centro de Astrobiología (CAB, CSIC-INTA) is part, has discovered two small terrestrial planets around the Teegarden Star, a red dwarf star in the solar neighborhood. Both planets have a mass similar to Earth's and their temperature could be mild enough to hold liquid water on their surface. 

Located at a distance of only 12.5 light-years, in the constellation Aries, with a radius seven times smaller than the solar and 8% of the mass of the Sun, the Teegarden Star is one of the smallest known red dwarf stars. Despite its proximity, the Teegarden Star is so dim (1,500 times weaker than the Sun) that it was not identified until 2003. The observations that have allowed the discovery of the planets have been made with the CARMENES instrument (Calar Alto High-Resolution Search for M dwarfs with Exoearths with Near-infrared and optical Échelle Spectrographs), an optical and infrared spectrograph high-resolution, built in collaboration with 11 Spanish and German research institutions, including the Centro de Astrobiología. CARMENES is installed on the 3.5m telescope of the German Hispanic Astronomical Center in Calar Alto, Almería.

The method used for the detection of planets is known as the Doppler technique. When a planet moves in its orbit around a star, it causes a small movement of zooming in and out that induces a subtle Doppler displacement effect on observed light coming from the star. The sensitivity of the CARMENES instrument is such that it can measure this displacement with great precision.

Doppler measurements of the Teegarden Star showed the presence of at least two new exoplanets, which have been called Teegarden b and c. Data indicate that the planet Teegarden b, located at a star distance of 2.5% of the Earth-Sun distance, has a mass similar to that of Earth and an orbital period of 4.9 days. The planet Teegarden c is also similar to Earth in terms of mass, completing its orbit in 11.4 days and 4.5% away from the Earth-Sun distance. Since the Teegarden Star radiates much less energy than the Sun, temperatures on these planets should be tempered and could, in principle, house liquid water on its surface, especially the outermost, Teegarden c. These types of planets are the main target for future life searches beyond our solar system.


Fuente: UCC-CAB

Fecha: 2019-06-18


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