What is a red dwarf?

Red dwarves are small, relatively cool stars that are the largest type of star in our galaxy, not if in space. It is difficult to verify because red dwarves are not too light (ranging from 0.01% to 10% luminosity of the sun), which is difficult to observe them from astronomical distances. Proxima Centuari, the closest star of the solar system, is a red dwarf.

Red dwarves have a weight of between 7.5% and 50% of the mass of the sun. Massive stars are called yellow dwarves, while less massive are called brown dwarves. All dwarves are part of the most common class of stars, known as the "main sequences". Outside the main sequence are white dwarves who have exhausted their nuclear fuel, and giant stars that swell to form a starbine or explode to supernova. But because the red dwarves are less massive core is less compact and the reactions take place at a slower pace than in larger stars. The surface temperature of the red dwarf is therefore smaller notPs 3 500 K, which is significantly than the surface temperature of the sun, which is about 5 778 thousand.

Red dwarves are small enough to be fully convective, which means that the material in the core and surface is constantly recirculated. For this reason, the red dwarfs are able to burn a larger part of their nuclear fuel than more massive stars. Combined with a low level of nuclear reactions from their low compression, it gives red dwarves a huge lifetime: from tens of millions to trillion years depending on weight.

One mysterious thing on the red dwarfs is that they lack what is called "metals" in astronomical speech, which means other elements than hydrogen or helium. Because most of the stars in space are born from detritus supernova, which contains many metals, one would expect that all stars except the first stars in the universe will contain heavier elements. Yet they are nowhere found in the red dwarfku.