So it’s our sun’s destiny to become a red giant star (and afterwards a white dwarf, and then a black dwarf). So you can see that our sun is one of the stars that will inevitably, someday, become a red giant. Astronomers call such stars low- or intermediate-mass stars. To become a red giant, a particular star must have between half our sun’s mass, and eight times our times our sun’s mass. Please donate what you can to our annual crowd-funding campaign. Interested in stars? Help EarthSky bring them to you. They’ll end their lives as a so-called black dwarf: a tiny, burned-out, virtually-invisible cinder. Eventually, after billions of years, these stars will become totally cold and radiate no energy. Then the star will slowly contract and cool to become a white dwarf: Earth-sized, ultra-dense star corpses radiating a tiny fraction of their original energy. Once at the red giant stage, a star might stay that way for up to a billion years. It has slowly swollen up to many times its original size. What are red giants?Ī red giant is a star in its death stages. Image via NASA Goddard Space Flight Center/ Chris Smith (KBRwyle). Artist’s concept of the evolved stars known as red giants, at different distances in this illustration.

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