An exoplanet, with half the mass of Venus – the lightest ever measured using radial velocity technology – an ocean world and a potential planet in the habitable zone just 35 light-years from Earth around the star L98-59, has been discovered by an international team from astronomers Led by Olivier Demangon, a researcher at the Institute of Astrophysics and Space Sciences (He) e do Department of Physics and Astronomy Give Faculty of Science, University of Porto.
The team that published an article about the discovery on Thursday in the scientific journalAstronomy and astrophysics“, Use the ESPRESSO instrument from the European Southern Observatory’s (ESO) Very Large Telescope (VLT), located in the Atacama Desert in Chile, to shed new light on these outer planets, which are similar to the inner planets of our solar system (Mercury, Venus and Earth). Portugal is a member country of ESO.
“This is the exoplanet with the smallest mass measured using the radial velocity method, being even smaller than Earth,” he explains. Susanna Barros, who is also a researcher at the IA and the University of Porto, adding that “this measurement was only possible due to many years of improvements in tools and data analysis techniques, to which IA members have made important contributions.” The radial velocity method detects exoplanets by measuring small differences in the (radial) velocity of the star, due to the motion that the orbits of these planets impart on the star. Using this method, it is possible to determine the minimum value of its mass.
The team of astronomers has discovered a fourth planet and it is also suspected that there is a fifth planet in the habitable zone, i.e. The region is at the correct distance from the star so that it can contain liquid water on its surface. “We found evidence to suggest the existence of a terrestrial-type planet located in the habitable zone of this system,” explains Olivier Demangon.
These findings are an important advance in the search for life on Earth-sized planets outside the solar system. Detecting signs of life, or so-called bioprints, depends largely on astronomers’ ability to study its atmosphere. However, current telescopes still lack sufficient diameter to reach the resolution needed to perform this type of study on small, rocky planets. Therefore, the L98-59 planetary system is a good target for future observations of the atmospheres of exoplanets.
The team used the ESPRESSO instrument to study the L 98-59 system and were able to conclude that three of the planets may contain water either in their interiors or in their atmospheres. The two planets closest to the star are likely dry, but they may still contain small amounts of water. A third planet may contain up to 30% of its mass in water, so it appears to be an ocean world.
Challenge the limits of planetary discovery
to the principal investigator Planetary Systems Team to IA, Nuno Cardoso SantosESPRESSO has been meticulously created so that we get results like these and challenge the limits in discovering other worlds. All the investments that have been made “are now paying off and it is important to see that the Portuguese team is at the forefront of these results”.
Astronomers first saw three of the planets in the L 98-59 system in 2019, using NASA’s TESS satellite, through a so-called transit method, which It consists in measuring the drop in light from the star caused by the passage of an exoplanet in front of it, something similar to a small eclipse. By transit it is possible to determine only the radius of the planet, its size. However, only by adding radial velocity data obtained by the ESPRESSO instrument and its precursor, HARPS, Olivier Demangon and his team were able to find more planets in this system and measure the masses and radii of the first three. “If we want to know how a planet is formed, we need, at a minimum, to know its mass and radius,” explains researcher IA.
The team hopes to continue studying this system using the future James Webb Space Telescope from NASA, the European Space Agency (ESA), and the Canadian Space Agency. The Very Large Telescope (ELT) from ESO, currently under construction in the Atacama Desert in Chile, and which will start operating in 2027, would be ideal for studying these planets. “god recruitment, which will be installed in the ELT, will be able to study the atmospheres of some planets in the L98-59 system, thus completing the James Webb Space Telescope from Earth”, says Maria Rosa Zapatero Osorio, astronomer at the Astrobiology Center Madrid and co-author of the scientific article The post adding that “The rocky planet half the mass of Venus now discovered in the habitable zone may have an atmosphere capable of protecting and supporting life.”. NSIn “the accuracy and stability provided by ESPRESSO, this measurement was not possible,” says the Spanish astronomer, stressing that “this is a step forward in our ability to measure the masses of the smallest planets outside the solar system.”
“We’ve been searching for Earth-type planets since the birth of astronomy,” says Olivier Demangeon. “Now we are getting closer and closer to discovering a terrestrial planet in the habitable zone of its star where its atmosphere can be studied.”
The participation of artificial intelligence in ESPRESSO is part of a broader strategy to enhance the search for exoplanets in Portugal, through the construction, development and scientific definition of various space instruments and missions, such as the mission Khufu (European Space Agency), already in orbit. This strategy will continue for years to come with the launch of the space telescope plateau (ESA), Mission Ariel (European Space Agency) and the installation of the HIRES spectrometer at the ELT, which will be the largest next-generation telescope.
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