Red dwarf

What is a Red Dwarf?

A red dwarf is a small, cool kind of star that shines on its own. These stars are very common in the universe, especially in our own Milky Way galaxy. One of the closest stars to the Sun, called Proxima Centauri, is a red dwarf.

Red dwarfs are smaller and cooler than our Sun. Some of the smallest red dwarfs are about one-tenth the width of the Sun and have temperatures around 2,000 K. Even though they are tiny, red dwarfs can last for a very, very long time—much longer than the current age of the universe.

Fun Facts About Red Dwarfs

Because red dwarfs use their fuel slowly, they stay the same for trillions of years. They only change when they finally run out of fuel and become a different kind of star called a blue dwarf. Scientists think red dwarfs might be good places to look for planets that could support life.

Red dwarfs are the most common type of star in space. Even though they don’t shine very brightly, we can see many of them with special tools. They help scientists learn about how old groups of stars are and even how old the universe might be.

Red Dwarfs and Planets

Many red dwarf stars have planets, called exoplanets, around them. Smaller planets, about the size of Neptune or the Earth, are more common around red dwarfs than big planets like Jupiter. Some red dwarfs have planets in the "habitable zone," where liquid water could exist.

One famous red dwarf star system is Gliese 581. Scientists found several planets there, some of which might be able to have liquid water. In 2017, NASA found seven Earth-sized planets around a red dwarf star named TRAPPIST-1. Three of these planets are in the habitable zone and could possibly have liquid water.