Astronomers discover super-Earth in the habitable zone
Is there life out there? Another method should make it possible to find habitable planets. A super-Earth in the habitable zone was discovered in this way.
Artist's impression of the Kepler-725 system with the two planets
(Image: GU Shenghong)
A team of researchers has discovered a new exoplanet in the system of the star Kepler-725. According to the astronomers, the planet is located in the habitable zone.
Kepler-725 is a main sequence star of spectral class G, also known as a yellow dwarf. It therefore belongs to the same class of stars as the sun. The system is just under 2500 light years away from Earth.
The planet Kepler-725c is a so-called super-Earth and has about ten times the mass of our Earth. The planet orbits its central star in 207.5 days on an elliptical orbit with an eccentricity of 0.44, the researchers write in the journal Nature Astronomy.
According to their data, the planet is located in the habitable zone of its star. This is the area around a star in which conditions prevail on a planet for water to occur in a liquid state. This is the prerequisite for life as we know it. The average irradiation is about 1.4 times the value on Earth.
The first planet made the discovery of the second possible
Kepler-725c is not the first planet to be found in this system: Kepler-725b is a gas planet, a hot Jupiter, which orbits the star in just under 40 days. This was used by the team led by L. Sun from the Yunnan Observatories of the Chinese Academy of Sciences to find the smaller Kepler-725c. Planets are usually discovered using the transit method. A planet is detected indirectly by observing the brightness of its star.
To find Kepler-725c, the researchers used the Transit Timing Variation (TTV) method. This involves measuring temporal variations in the transits – in the case of Kepler-725b – and thus determining the mass and orbital parameters of the second planet.
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It is the first time that a planet has been discovered using the TTV method, the researchers said. It is better suited for the discovery of small planets than the transit or RV method. It is hoped that it will be used to find habitable planets in other star systems during the future PLATO mission from Europe and Earth 2 from China.
(wpl)
