The universe is full of stars, and they’re not all the same. In fact, there’s an incredible variety. Here’s a sampler of the most extreme stars in the known universe.
The way stars work, the less massive they are, the longer they tend to live. The stars with the smallest mass are the red dwarfs. They can be anywhere from 7.5 to 50 percent of the Sun’s mass. Anything less massive wouldn’t be able to do nuclear fusion—it wouldn’t be a star.
Current models estimate that the smallest red dwarf stars could do fusion for up to 10 trillion years. Compare that to stars like our Sun, which do fusion for around 10 billion years—1,000 times less. After fusing most of its hydrogen, theory predicts that a lightweight red dwarf becomes a blue dwarf, and as it uses up the rest of its hydrogen, core fusion stops and it becomes a white dwarf.