From an astronomical point of view, it’s literally around the corner: Ross 508 is a red dwarf located just 36.6 light years away in the constellation Serpens. Around this small star, a group of Japanese astronomers led by Hiroki Harakawa Potentially habitable rocky planet recently discovered: Ross 508 bso-called super earth. The discovery was made possible by a relatively new technique using a new Japanese telescope instrument. Subaruin Hawaii.
What is a super earth
There are three classes of planets in our solar system: terrestrial planets (such as Earth), ice giants (Uranus and Neptune), and gas giants (Jupiter and Saturn). However, these are not the only possible types of planets. A class of particular interest, especially for astrobiologists, is the class super-earths, rocky planets that are about 5-10 Earth masses (therefore have an intermediate mass between that of the terrestrial planets and that of the ice giants). That’s why astronomers are always excited when they discover a new super-Earth!
What is interesting about Ross 508 b
L’habitability A planet is currently defined as its ability to host pools of liquid water on its surface. Therefore, a planet is potentially habitable when its surface temperature is between 0°C and 100°C. Therefore, each star is equipped with a so-called habitable strip, which corresponds to the range of distances from the star itself, at which the planet, in principle, can contain liquid water. The idea is simple: tell me how hot a star is and I’ll tell you where it is and how wide its habitable band is.
on the picture: The distance to a star’s habitable belt as a function of its surface temperature, as well as the distance to Earth (within the Sun’s habitable belt) and to some solar and extrasolar planets (Credit: Chester Harman).
The most interesting thing about Ross 508 b is that it lies close to the inner edge of its parent star’s habitable belt. Found only in 0.05 AU from its star (i.e. 5% of the Earth-Sun distance), but on the other hand, Ross 508 is much less hot than the Sun: 2800°С against 5500°C of our star. Therefore, its brightness is very small: only 3 thousandths from the sun. So yes, Ross 508 b is very close to its star, but just as close to its habitable belt.
According to astronomers, this planet he only receives 40% of the radiation respect for what Land. In other words, it is located near the inner edge of the habitable belt of the star Ross 508. In addition, the orbit of this planet is quite eccentric (i.e. “flattened”), so part of its orbit lies within the star’s habitable belt. If we take into account that the planet is rocky, then we can speak of a “planet”. potentially habitable“.
But be careful: “potentially habitable” does not mean “residential” or “inhabited”.. We still know too little, for example, about this planet’s atmosphere and what kind of greenhouse effect it can produce. In addition, red dwarfs such as Ross 508 tend to be more “nervous” stars than our Sun, often emitting flares, even quite strong ones, capable of sterilizing the planets that are near these stars. Therefore, further studies will be required to confirm or refute the actual habitability of Ross 508 b.
Why Discovery Matters
On the other hand, it is true that red dwarfs (that is, stars with a mass between 8% and about 60% of the mass of the Sun) make up about 75% of the stars in our universe. So the search for habitable planets around these stars is extremely promising.
on the picture: Proxima Centauri, the closest star to the Sun, is a red dwarf. There are an estimated 220 billion red dwarfs in our galaxy.
One method for finding planets around these stars is the so-called radial velocity method. When a planet moves around a star, the latter naturally shifts slightly from the planet. Astronomers can measure speed this little shift (radial velocity), which provides trial fromExistence planets.
This is mainly done by splitting and analysis of visible light emitted by a star. However, red dwarfs emit predominantly infrared light due to their relatively moderate temperatures. This is why the Subaru telescope (which means Pleiades in Japanese) is equipped with an instrument (called IRD, InfraRed Doppler) capable of doing this job using infrared light. This will allow us to discover many more planets around red dwarfs in the future than we have so far.
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