Dwarf star facts for kids
Dwarf stars are a special group of stars. The word "dwarf" was first used in 1906 by a Danish astronomer named Ejnar Hertzsprung. He noticed that the reddest stars, which were called K and M stars, fell into two main groups. Some were much brighter than our Sun, and others were much fainter. To tell them apart, he called the brighter ones "giant" stars and the fainter ones "dwarf" stars.
Over time, the term "dwarf" grew to include several different kinds of stars.
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What is a Dwarf Star?
Most of the time, when people say "dwarf star," they are talking about any main-sequence star. These stars are in the longest part of their lives, steadily burning hydrogen into helium in their cores. Our own Sun is a main-sequence star, and it's also a type of dwarf star!
Types of Dwarf Stars
There are a few different kinds of dwarf stars, each with its own unique features:
Red Dwarfs
Red dwarfs are small and cool main-sequence stars. They are the most common type of star in the universe. They burn their fuel very slowly, which means they can live for trillions of years! Because they are so small and cool, they don't shine very brightly.
Yellow Dwarfs
Yellow dwarfs are main-sequence stars that are similar in size and temperature to our Sun. They are called "yellow" because their light looks yellowish-white. Like our Sun, they are in the middle of their lives, steadily fusing hydrogen.
White Dwarfs
A white dwarf is what's left of a star after it has used up most of its fuel. Stars like our Sun will eventually become white dwarfs. When a star runs out of hydrogen, it expands into a red giant, then sheds its outer layers, leaving behind a very dense core. This core is the white dwarf. It's super small, about the size of Earth, but incredibly heavy! It slowly cools down over billions of years.
Black Dwarfs
A black dwarf is a theoretical star. It's a white dwarf that has cooled down so much that it no longer gives off any heat or light. Scientists believe it would take an extremely long time for a white dwarf to cool completely, much longer than the current age of the universe. So, no black dwarfs have been found yet!
Brown Dwarfs
A brown dwarf is sometimes called a "failed star." It's bigger than a planet but not quite big enough to be a true star. Brown dwarfs don't have enough mass to start the main process of fusing hydrogen into helium like the Sun does. However, they are massive enough to fuse a lighter element called deuterium. They are much fainter than regular stars and are hard to spot.
See also
In Spanish: Estrella enana para niños
