This is the background to the discovery of super-Earth HD 20794 d by an international team including the University of Geneva (UNIGE) and the NCCR PlanetS.
This is the case of planet HD 20794 d, which has just been detected by a team that includes members of the UNIGE Astronomy Department.
The exoplanet HD 20794 d takes 647 days to orbit its star, around 40 days less than Mars.
The discovery of HD 20794 d provides scientists with an interesting laboratory for modeling and testing new hypotheses in their search for life in the universe.
Knowing whether this planet harbors life will still require a number of scientific milestones and a transdisciplinary approach.
Over 7,000 exoplanets have been found in our galaxy by astronomers in the thirty years since the first one was discovered. Nevertheless, billions more are yet to be found. In an effort to discover extraterrestrial life, exoplanetologists have started to interest themselves in their features. The University of Geneva (UNIGE) and the NCCR PlanetS were part of an international team that discovered super-Earth HD 20794 d.
The new planet’s orbit is eccentric, meaning it moves in and out of the habitable zone of its star. The results of 20 years of observations with the world’s best telescopes led to this discovery. Astronomy and Astrophysics is the journal where the findings are published.
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Only recently has modern science started to offer credible theories and evidence to address the age-old philosophical question, “Are we alone in the universe?”. Astronomers are making slow progress, though.
By expanding the boundaries of knowledge, every new findingāwhether theoretical or observationalācontributes to the structure. The first planet orbiting a star other than the sun was discovered in 1995, and two UNIGE researchers, Michel Mayor and Didier Queloz, were awarded the 2019 Physics Nobel Prize for their work. According to current scientific consensus, each star in our galaxy has a planetary system.
In order to test their theories and expand their knowledge, astronomers are currently searching for exoplanets with intriguing features or those that are simpler to describe. The UNIGE Astronomy Department is part of a team that recently detected the planet HD 20794 d.
around its star’s habitable zone.
This planet is a super-Earth, which is a telluric planet that is bigger than Earth. Along with two other planets, it is a member of a planetary system. Like the sun, it orbits a G-type star only 19 points seven light-years away, which is very close to Earth on the universe’s scale.
Its “closeness” facilitates study because its light signals are stronger and more noticeable. “HD 20794, around which HD 20794 d orbits, is not an ordinary star,” describes Xavier Dumusque, a co-author of the study and a senior lecturer and researcher in the UNIGE Department of Astronomy.
Because of its brightness and closeness, it is a perfect fit for upcoming telescopes whose purpose is to directly observe exoplanet atmospheres. “.
The planet HD 20794 d is of interest because it is located in the habitable zone of its star, which demarcates the area where liquid water can exist and is one of the prerequisites for the emergence of life as we know it. This region is influenced by a number of variables, chiefly the stellar characteristics.
It can span from 0.7 to 1.5 astronomical units (AU) for stars like the sun or HD 20794, which includes both the Earth’s and, in the case of the sun, Mars’ orbits. Approximately 40 days less time is needed for the exoplanet HD 20794 d to orbit its star, taking 647 days.
During its revolution, HD 20794 d’s trajectory is elliptical, with significant variations in the distance to its star, as opposed to a relatively circular orbit like that of Earth or Mars. Thus, the planet’s orbit oscillates between the outer edge of its star’s HZ (2 AU) and the inner edge (0-75 AU).
Astronomers are particularly interested in this configuration because it enables them to modify theoretical models and test their comprehension of the concept of a planet’s habitability. If water exists on HD 20794 d, it would transition from an ice to a liquid state during the planet’s orbit around the star, which would allow life to appear.
Years of observations.
The process of detecting this super-Earth was iterative and difficult. Using cutting-edge tools like ESPRESSO and HARPS, the team examined over 20 years’ worth of data. The scientists used YARARA, a data reduction algorithm that was recently created at the UNIGE, for the latter.
It had been hard to tell if planets were real for years because noise had masked planetary signals. Michael Cretignier, an Oxford University post-doctoral researcher who co-authored the study and developed YARARA during his Ph.D., says, “We analyzed the data for years, carefully eliminating sources of contamination.”. D. at UNIGE. .
In their quest for extraterrestrial life, scientists now have an intriguing lab to model and test new theories thanks to the discovery of HD 20794 d.
Next-generation instruments like the ANDES spectrograph for ESO’s Extremely Large Telescope (ELT) are particularly interested in this planetary system because of its closeness to its bright star. It will still take several scientific advances and a transdisciplinary approach to determine whether life exists on this planet.
The UNIGE’s Faculty of Science’s new Center for Life in the Universe (CVU) is already researching the conditions for its habitability.