Astronomers have discovered the source of the atmosphere for planets orbiting red dwarf stars.

Red dwarfs are known for their exceptionally strong flares. A number of astronomers believe that if such a star were in the place of the Sun, there would be no life on Earth: the radiation would leave it with no chances and would completely "blow away" our atmosphere. As a result, many scientists have little hope for planets around red dwarfs in terms of searching for extraterrestrial life (although others actively disagree with them).

Such an example has been observed in recent years in the immediate vicinity of the Solar System — less than 35 light-years away from us, in the southern constellation of Pisces Austrinus. There lies the exoplanet L 98-59 b, which has a mass of about half that of Earth, and its size is something between Earth and Mars.

It orbits just over three million kilometers from its star — a red dwarf — completing a full orbit in just two days. For comparison, the average distance between Mercury and the Sun is about 58 million kilometers, and it takes nearly 88 days to make a complete orbit.

In such close proximity to its star, L 98-59 b is undoubtedly in what is known as tidal locking — it is always facing the star with the same side. This results in the planet being divided into two distinct zones: one of eternal day and one of eternal night. The daytime side is estimated to receive 22 times more energy than Earth does from the Sun.

Additionally, the orbit of this planet is quite elongated. This means that L 98-59 b alternately approaches and moves away from its star, and the star's gravity stretches and compresses the planet slightly. This creates internal friction, which further heats the planet. This phenomenon is referred to as tidal heating. According to planetary scientists, this is similar to what occurs with Jupiter's moon Io — the famous volcanic moon of the gas giant.

Until now, it was suspected that L 98-59 b might not have an atmosphere, or that it is so dense that it does not allow light to pass through. Recently, a team of American astronomers discovered that there is indeed an atmosphere. The scientists shared their findings in an article available on the Cornell University preprint server (USA).

It turned out that while observing the exoplanet using the James Webb telescope, they obtained light characteristics that, when modeling different scenarios, best matched an atmosphere very rich in sulfur dioxide, which is one of the main components of volcanic emissions. It is estimated that the exoplanet experiences tidal heating and, consequently, volcanism that is eight times stronger than that of Io.

It should be noted that the star, and thus the entire system, is still very young, at only about 800 million years old. In comparison, the Solar System is over four and a half billion years old. Nonetheless, according to astrophysicists, even within such a short time frame, in cosmic terms, the original atmosphere of L 98-59 b could not have been preserved: if it existed, the flares from its parent star would have long since destroyed it. Therefore, researchers concluded that they are observing a secondary atmosphere that is constantly being replenished by new eruptions.