Astronomers have discovered a new super-Earth orbiting the habitable zone of HD 20794, a Sun-like star only 20 light years away. This discovery is crucial in the search for planets that could harbour life, as the habitable zone is where conditions could allow the presence of liquid water, a key ingredient for life as we know it.
The new planet, called HD 20794 d, has a mass six times that of Earth and takes 647 days to orbit its star. Its orbit places it in the habitable zone, where it could theoretically support liquid water on its surface. However, its eccentric orbit and high mass make it very different from Earth.
The discovery was made possible by more than 20 years of observations of the radial velocity of the star HD 20794, carried out with advanced spectrographs such as ESPRESSO and HARPS, installed at the ESO observatories in Chile. These instruments detected small variations in stellar velocity caused by the gravity of orbiting planets, allowing scientists to identify the planet in 2022.
Although HD 20794 d is in the habitable zone, it is too early to determine whether it could host life. Its elliptical orbit and large mass make it a very different planet from Earth, and the variation in its distance from the star could affect surface conditions.
