A new world has just been found orbiting a Sun-like star only 20 light-years away, and it could be one of the most promising places to study Earth-like atmospheres.
Scientists have confirmed the existence of HD 20794 d, a super-Earth that takes 647 days to orbit its star, placing it within the habitable zone — the region where liquid water might exist. This breakthrough, built on more than two decades of observations, opens the door to studying planetary atmospheres with next-generation telescopes.
Discovery of a New Super-Earth
The Instituto de Astrofísica de Canarias (IAC) and the Universidad de La Laguna (ULL) have confirmed the discovery of a super-Earth orbiting in the habitable zone of HD 20794, a nearby Sun-like star. This finding, based on more than 20 years of observations, provides a valuable opportunity to study the atmospheres of Earth-like planets in greater detail.
Searching for planets in the habitable zones of Sun-like stars is key to understanding the potential for life beyond Earth. It also helps scientists explore conditions similar to those that allowed life to develop on our own planet. HD 20794, a star slightly smaller than the Sun and located just 20 light-years away, has long been a subject of scientific interest. This latest discovery marks the third planet identified in its system, following the confirmation of two other super-Earths more than a decade ago.
A Super-Earth in the Habitable Zone
The newly discovered planet, HD 20794 d, is a super-Earth with a mass six times that of Earth. It takes 647 days to complete one orbit around its star — about 40 days less than Mars’ orbit around the Sun. This orbit places it within the star’s habitable zone, meaning it is at a distance where liquid water could potentially exist on its surface, one of the essential ingredients for life as we know it.
It is precisely the combination of the planet’s distance from its star and the proximity of the system that makes it particularly attractive, rendering it a perfect candidate for observations with the ELT, ESO’s 40-meter telescope, or future space missions by ESA and NASA. “This is the perfect type of planet for characterizing terrestrial planet atmospheres with next-generation instruments and missions,” explains Nicola Nari, a researcher at Lightbridges S.L., a doctoral student at the Universidad de La Laguna and the study’s lead author, published recently in the journal Astronomy & Astrophysics. “In fact, we know of very few similar planets,” notes Alejandro Suárez Mascareño, a researcher at the IAC and co-author of the work. “This will surely be one of the first we can study,” adds.
Two Decades of Cutting-Edge Observations
This discovery was made possible thanks to over 20 years of radial velocity measurements from the ESPRESSO and HARPS spectrographs, both installed at ESO observatories in Chile. These instruments, among the most advanced in the world, can measure the tiny variations in stellar velocity caused by the gravitational pull of planets in a system. “Very few instruments in the world can achieve the level of precision required for a discovery like this,” explains Nicola Nari.
To go even further, the team applied sophisticated processing techniques to the spectra obtained. “We worked on data analysis for years, gradually analyzing and eliminating all possible sources of contamination,” explains Michael Cretignier, a co-author of the study and researcher at the University of Oxford. This meticulous analysis revealed the presence of a candidate signal identified in 2022. The team immediately launched a new observation campaign to confirm it. “After two years of adding new measurements, we can confirm we have a robust detection,” adds Nathan Hara, a researcher at the Marseille Astrophysics Laboratory.
What Does This Mean for Habitability?
Although the planet is located in the system’s habitable zone, it is too early to say whether it could host life. Its high mass and eccentric orbit make it a very different world from ours. Unlike most planets in the Solar System, HD 20794 d’s orbit is not circular but elliptical. Its distance from its star changes significantly, causing the planet to move from the outer edge of the habitable zone to the inner edge throughout its year. “HD 20794 d is not a second home for humanity, but its position and peculiar orbit give us a unique opportunity to study how the conditions for habitability vary over time and how these variations may influence the evolution of the planet’s atmosphere,” says Alejandro Suárez Mascareño, researcher at the IAC and co-author of the work.
Explore Further:
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Reference: “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” by N. Nari, X. Dumusque, N. C. Hara, A. Suárez Mascareño, M. Cretignier, J. I. González Hernández, A. K. Stefanov, V. M. Passegger, R. Rebolo, F. Pepe, N. C. Santos, S. Cristiani, J. P. Faria, P. Figueira, A. Sozzetti, M. R. Zapatero Osorio, V. Adibekyan, Y. Alibert, C. Allende Prieto, F. Bouchy, S. Benatti, A. Castro-González, V. D’Odorico, M. Damasso, J. B. Delisle, P. Di Marcantonio, D. Ehrenreich, R. Génova-Santos, M. J. Hobson, B. Lavie, J. Lillo-Box, G. Lo Curto, C. Lovis, C. J. A. P. Martins, A. Mehner, G. Micela, P. Molaro, C. Mordasini, N. Nunes, E. Palle, S.P. Quanz, D. Ségransan, A. M. Silva, S. G. Sousa, S. Udry, N. Unger and J. Venturini, 28 January 2025, Astronomy & Astrophysics.
DOI: 10.1051/0004-6361/202451769
Researchers from the IAC, including Jonay I. González Hernández, Atanas K. Stefanov, Rafael Rebolo, Carlos Allende Prieto, and Enric Pallé, also contributed to this publication.
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4 Comments
Catapult Musk there.
At currently achievable space travel speeds, it is going to only take half million years…..
If one’s space-craft were to accelerate continuously at 2 feet per day per day, after about 3 months it would be knocking along at the right old speed of 1237940039285380274899124224 feet per day, which in mph would be divided by 5280 and 24 which kept simple would be 5000×20, or approx 100 000 (1 x10 power 5). Calling the right old speed 1.23 x 10 power22 mph my guess is that the space craft would have crossed the light barrier some few days earlier and might have become very heavy; or something. Of course we have to think in terms of light years, one of which is 6 x 10 power12 miles, but one’s space-craft could knock that off pretty smartly ending up at at what, 9 billion mph? (must be a decent accountant somewhere to sort this out? Just a few simple sums).
So yes, we could get to that planet in just a few weeks. You would need some good seat belts if you wanted to stop in the couple of days needed for a safe landing.
“This orbit places it within the star’s habitable zone, meaning it is at a distance where liquid water could potentially exist on its surface, one of the essential ingredients for life as we know it.”
It is only within the optimistic HZ for about half its orbit, so the habitability is in question. They say:
“The stellar flux at the periastron is almost seven times stronger than the stellar flux at the apoaster. HD 20794 d spends ∼59% of its orbit inside the optimistic HZ, and ∼38% of its orbit inside the conservative HZ. Biasiotti et al. (2024) investigated the habitability of planets crossing the HZ for just a fraction of their orbit, as is the case for GJ 514 b (Damasso et al. 2022). This planet has a similar eccentricity to HD 20794 d. The level and number of tests of their analysis are beyond the scope of this work. In their
work, we can see how habitability could be possible for planets on high-eccentric orbits based on stellar and planetary parameters such as stellar age, CH4 abundance in the atmosphere, axis obliquity, ocean fraction, rotation period of the planet, and other properties. The possibility of maintaining habitable conditions even in a highly eccentric orbit raises the interest in investigating the HD 20794 system in future studies. “