Science & Technology

Discovery of a strange solar system with six exoplanets

Carmen Rodríguez

Madrid, Nov 29 (EFE).- A solar system that has not experienced significant changes since its formation seems very rare, but that is the case of a star over a hundred light-years away.

The star HD110067, in the northern constellation of Coma Berenices, was already known to scientists, but not its exoplanets.

A team led by Spanish astrophysicist Rafael Luque from the University of Chicago published their discoveries about this system in the journal Nature, providing a unique insight into planetary formation and evolution.

This system is “very peculiar” due to several characteristics, explains Luque. It is one of the very few known with all its planets in resonance, meaning patterns repeat as they orbit the star.

In this case, its six planets maintain that resonance following a precise rhythm, forming a unique pattern for each pair, making it an exceptional case.

Such resonance occurs at the system’s formation, but chaotic processes often disrupt it in the early millions of years. This system, however, has retained its configuration since its formation around a billion years ago.

As a result, in 99% of cases, the planets are redistributed in “somehow arbitrary” orbits, losing resonance, explains Enric Pallé, a member of the Institute of Astrophysics of the Canary Islands in Spain and one of the authors of the study.

From Earth’s perspective the six planets transit in front of their star. This, combined with the star’s brightness, turns this system into a unique laboratory, according to both astrophysicists.

These three characteristics will allow scientists to reconstruct the history of this system, going back in time to even establish how the dust and gas disk from which it formed looked. Something that is not possible with planets that have shifted from their orbits, Pallé indicates.

The international team that signs the study, has used observations from various instruments to characterize the system of the star HD110067, including the CHEOPS satellite from the European Space Agency, NASA’s Tess, the CARMENES spectrograph in Almería, Spain and the HARPS-N instrument in La Palma, Spain.

Other characteristics, such as the mass, size, and radius of each planet, have been determined by them as well. It has been noted that they are too close to the star to be within the habitable zone, but water is still a possibility.

The orbits are estimated to range from about nine days for the innermost planet and around 54 days for the outermost planet. All six exoplanets are sub-Neptunes, meaning their radii fall between that of Earth and Neptune.

Pending new data from the James Webb Space Telescope, it is known that their atmospheres are extensive and “likely composed mostly of hydrogen and possibly something more,” which says Luque, “we still don’t know what it is or in what quantity.”

The atmosphere probably has water because it is “very common in the universe,” but if methane and carbon dioxide were found, “it could indicate that there is liquid water in them” in their structure, although for now, we also don’t know what their surface is like.

Luque highlights that studying mini-Neptunes is an active field within exoplanet research, and having a system with six around the same star “eliminates many obstacles” in the understanding of these planets.

This discovery will likely deepen our understanding of these planets in the coming years, addressing questions about their formation, evolution, and atmospheric and internal composition through direct observations.EFE

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