Scientists find two interesting sub-Neptunes in the orbit of a red dwarf

The TESS Space Telescope has found two new exoplanets orbiting the star TOI 904. One of them is the coldest of those orbiting a red dwarf. Scientists are very interested in exploring this system.

Scientists find two sub-Neptunes. Source:

Two sub-Neptunes

Researchers working with the Transiting Exoplanet Survey Satellite (TESS) space telescope have reported the discovery of two new exoplanets orbiting the red dwarf TOI 904. The article about this is published in The Astrophysical Journal Letters.

Both planets belong to the sub-Neptunes class of sub-Neptunes. They are an intermediate link between super-Earths, generally similar to our planet, and small gas giants. Most of all, scientists are interested in the planet TOI 904b, which is more distant from the star. It makes one orbit around the star in 84 days, and the equilibrium temperature on the surface is -56 °C.

All this makes TOI 904b the coldest of the exoplanets that orbit red dwarfs. The second body in this system is much hotter, since it makes one orbit around the star in 11 days. This is a rather interesting combination of two very similar planets that orbit the same star at different distances.

Planets in red dwarf systems

Red dwarfs are small, cool stars with radii 2–3 times smaller than those of the Sun and surface temperatures of 2,700 K to 4,000 K. This is not the first time that planets around them have been found. In fact, of the approximately 7,000 candidates for new worlds discovered by TESS over the years, about 75 percent orbit these small stars.

And that’s what makes the red dwarf planets so interesting. These systems are the most widespread in the universe and, at the same time, quite different from our native one. First of all, the low luminosity of the star. Because of it, the “zone of life” in the system is located at a distance of only 1 AU from the sun. 

However, we usually don’t even see these planets. Most of the worlds that have already been discovered around red dwarfs are much closer to them. The opportunity to explore two sub-Neptures of the same system, the orbits of which have radii of 0.6 and 0.31 AU, is very rare. 

What makes it even rarer is the fact that both planets have almost similar radii (2.3 and 2.5 Earth radii). That is, they must be identical in everything except temperature. Because TOI 904b is too cold, and TOI 904c is too hot for life to exist. Therefore, scientists really want to find out if the chemical composition of their atmospheres will be somehow different.

According to

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