Tuesday , September 28 2021

Discover an exoplanet with more water than Earth

The search for exoplanets has been enhanced by a new discovery, this time completely unique: (for now) an exoplanet with truly unique properties.

outer planetNu2 Lupi dIt is located 50 light-years away around a star called Nu2 Lupi in the constellation Lupus. It is about 2.5 times the size of the Earth and about 9 times its mass.

How was Nu2 Lupi discovered?

The scientists who published the study used measurements with archival data from other observatories and numerical models to describe the density and composition of an exoplanet and its neighbors. They found that the planet had a rocky interior. And much more water than soil. But water is not liquid. Instead of getting high-pressure ice or high-temperature steam that makes planets uninhabitable.

In 2019, Swiss astronomers had already announced the discovery of three exoplanets with masses between Earth and Neptune (17 times that of Earth) and taking 12, 28 and 107 days to orbit their parent stars.

Jan AlbertProfessor of Astrophysics at the University of Bern and co-author of the study said: “We already knew this for the two inner planets, which led us to focus CHEOPS on the star system in the first place. The third planet is very far from the star: no one expected to see its transit!”

This was a turning point. It is the first time an exoplanet with a revolution period of more than 100 days has been seen passing by a star bright enough to be seen with the naked eye.”

Jan Albert

Because it is a unique discovery

Infographic of the Nu2 Lupi planetary system. Photo: ESA

David EhrenreichProfessor at the University of Geneva and the CHEOPS mission scientist, co-author of the study, said: “Because of the relatively long duration, the amount of stellar radiation reaching an exoplanet is considered moderate compared to many other exoplanets discovered. The less radiation a planet receives, the more over time it gets. “So a planet with a long period could retain more information about its origin.”

Until now, very few astronomers of these exoplanets have found faint stars in orbits. In other words: very little of its light reaches Earth and is therefore difficult to study. Not this time: The exoplanet is easier to study because its bright host star is close enough to us. This makes it a gold target for future work with no known equivalent.

David Ehrenreich

An exoplanet undergoing a slight eruption

Photobomb is the term for an object that suddenly falls into the camera’s field of view while taking a photo. The same thing happened with CHEOPS. The satellite was photographing a planetary system 50 light-years away and suddenly discovered this exoplanet that “blurred the picture”, but it turned out to be so.

The team was led by members of the Universities of Geneva and Bern and the PlanetS National Research Competence Center.

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