HD 20794 d NASA
In a groundbreaking discovery, an international team has confirmed the existence of a super-Earth orbiting in the habitable zone of a nearby Sun-like star—a potential haven for extraterrestrial life. Originally detected two years ago by Oxford scientist Dr. Michael Cretignier, this revelation is the culmination of more than two decades of meticulous observations. The findings, now published in Astronomy & Astrophysics, mark a significant leap forward in the search for Earth-like exoplanets, offering a tantalizing glimpse into worlds that may harbor the conditions necessary for life.
The newly discovered planet, HD 20794 d, boasts six times the mass of Earth and orbits a Sun-like star only 20 light-years away. Crucially, its orbit falls within the star’s habitable zone, the region where temperatures could allow liquid water to exist on the planet’s surface – a critical component for life as we understand it.
Dr Michael Cretignier first identified a candidate exoplanet signal in 2022, whilst analyzing archived data recorded by the HARPS (High Accuracy Radial Velocity Planet Searcher) spectrograph at the La Silla Observatory in Chile. This data analyses the light absorbed and emitted by objects.
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Dr Cretignier spotted distinct, periodic shifts in the spectrum of light emitted by the host star, which could have been caused by the gravitational pull of a nearby planet. Due to the faintness of the signal, however, it was not clear whether this was caused by a planet, induced by the star itself, or due to an instrumental error.
“For me, it was naturally a huge joy when we could confirm the planet’s existence,” Dr Cretignier said. “It was also a relief, since the original signal was at the edge of the spectrograph’s detection limit, so it was hard to be completely convinced at that time if the signal was real or not. Excitingly, its proximity with us (only 20 light-years) means there is hope for future space missions to obtain an image of it.”
“We worked on data analysis for years, gradually analysing and eliminating all possible sources of contamination,” added Dr Cretignier. “Advanced processing methods and meticulous analyses were needed to distinguish the planetary signal from background noise and subtle instrumental effects. By combining the results from the two instruments, the discovery was finally confirmed.”
Dr Cretignier concluded, “While my job mainly consists of finding these unknown worlds, I’m now very enthusiastic to hear what other scientists can tell us about this newly discovered planet, particularly since it is among the closest Earth-analogues we know about and given its peculiar orbit.”
The study “Revisiting the multi-planetary system of the nearby star HD 20794. Confirmation of a low-mass planet in the habitable zone of a nearby G-dwarf” has been published in Astronomy & Astrophysics.
