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An international group of astronomers has confirmed the existence of an exoplanet, HD 20794 d, which is located in the habitable zone of its star and may have conditions favorable for the existence of liquid water.
Planet HD 20794 d, which is about six times the mass of Earth, orbits a sun-like star just 20 light-years away. Its signal was first detected in 2022 by Dr. Michael Chrétien from the University of Oxford, who analyzed data from the High Accuracy Radial Velocity Planet Searcher (HARPS) spectrograph at the La Silla Observatory in Chile. Further studies have confirmed that HD 20794 d is in the habitable zone – the region where temperatures allow liquid water to exist, a key condition for potential life.
Methods for confirming discovery
To confirm the existence of the planet, the team of scientists analyzed spectral data collected over more than 20 years of operation of the HARPS and ESPRESSO (Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations) instruments. These spectrographs record changes in the light emission of a star caused by the gravitational influence of planets orbiting it. “We worked on analyzing the data for years, gradually analyzing and eliminating all possible sources of contamination,” said Dr. Chrétien. Combining information from the two independent instruments allowed us to definitively confirm the existence of HD 20794 d.
Orbit and the possibility of life
Although HD 20794 d is in the habitable zone, its orbit is elliptical, causing the planet to periodically move away from and toward its star. This means that the climate on its surface can undergo significant changes, periodically moving beyond the optimal conditions for the stable existence of liquid water. Scientists cannot yet say for sure whether the planet has an atmosphere that could smooth out these temperature fluctuations and maintain suitable conditions for life.
The significance of the discovery for future research
HD 20794 d will be a key target for further studies of Earth-like exoplanets. Due to its relative proximity to the Solar System, it could be one of the first exoplanets to be studied in detail by future missions such as the Extremely Large Telescope (ELT), the Habitable Worlds Observatory, and the Large Exoplanet Interferometer (LIFE).
Dr. Chrétien stressed the importance of this discovery:
Although the presence of life on HD 20794 d remains an open question, this discovery is an important step towards finding other worlds capable of supporting a biosphere. In the coming decades, new technologies will allow us to study the atmospheres of such exoplanets in more depth, which could bring us closer to answering one of the most important questions in science: is there life beyond Earth?
