A solar system that has not undergone major changes since its formation is very rare, but such is the case with a star more than a hundred light years away, surrounded by six planets, whose secrets are beginning to be revealed by science.

The star HD110067, in the northern constellation Coma Berenices, was already known, but its exoplanets were not. A team led by Spanish astrophysicist Rafael Luque, from the University of Chicago (USA), publishes its discoveries about this system in the journal Nature, which offers an unusual view on the formation and evolution of planets.

This system is “very special” because of several features, Luque explains to EFE. It is one of the few known to have all its planets in resonance, that is, with patterns that repeat as they move around their star, causing some to align every few orbits.

In this case, The six planets maintain that resonance, following a precise rhythm and following a unique pattern for each couple, representing an exceptional case.

This type of resonance occurs at the beginning of a system’s formation, but in the first million years a chaotic process usually takes place; for example, a very massive planet, an encounter with a nearby star or a gigantic impact can change that careful balance. .

The result is that in 99% of cases the planets are redistributed into “somewhat random” orbits, causing a loss of resonance, explains Enric Pallé, from the Institute of Astrophysics of the Spanish Canary Islands (IAC) and signatory of the study .

He the system now described is “extraordinary” – he adds – because it has maintained its configuration since its formation, which shows that it has not undergone major changes since its creation, estimated to be about a billion years ago.

In addition, The six planets pass in front of their starfrom the Earth’s perspective, something very unusual, which together with the great brightness of the Sun turns this system into a small laboratory or a test bench, both astrophysicists agree.

These three features will allow scientists to reconstruct the history of this system, going back in time to even determine what the disk of dust and gas from which it formed looked, something that is not possible with planets that are forming moved from their place. job, Pallé indicates.

The large international team behind the study used observations from the European Space Agency’s CHEOPS satellite, among others, to characterize the HD110067 galaxy; NASA’s Tess; the CARMENES spectrograph in Calar Alto (Almería, southern Spain) and the HARPS-N in Roque de los Muchachos (Spanish island of La Palma).

They are believed to be without water

Other features identified include the mass, size and radius of each, as well as that they are too close to the star to be in the so-called habitable zone, although it cannot be ruled out that there is water. .

The orbits are estimated to range from about nine days for the inner planet to about 54 days for the outer. and the six exoplanets are sub-Neptunes, that is, their radii lie between those of Earth and those of Neptune.

While we wait for the James Webb Space Telescope to acquire new data on its atmosphere, it is known that these are extensive and “probably composed mainly of hydrogen and perhaps something else, which – says Luque – we still don’t know what it is is or in what quantity”.

It is likely that there is water in the atmosphere as it is ‘very common in the universe’, but if methane and carbon dioxide were found “It could indicate that there is water in liquid form” in their structure, although it is currently unknown what their surface looks like.

A planetary system formed by six sub-Neptunes, or mini-Neptunes, offers many research opportunities, because these types of planets are the most numerous in the Milky Way, although none exist in the Solar System.

Luque emphasizes that research into mini-Neptunes is one of the most active fields in exoplanets and that having a system of six around the same star “removes many of the obstacles” to understanding these types of planets.

It is “a laboratory” where you can observe what the atmospheres of the different planets look like and what the possible differences are depending on the distance at which they were formed from the star, Pallé indicates.

In addition, it will allow other uncertainties that still exist about the formation, evolution and atmospheric and internal composition of these types of planets to be addressed through direct observations. (JO)