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Do white dwarf stars have “Goldilocks zones,” or are they too cold to sustain such regions?

Thomas C. Ferber, Chandler, Arizona
RELATED TOPICS: WHITE DWARFS | HABITABLE ZONE
Goldilocks zones
Yes, indeed, white dwarf stars can have “Goldilocks zones” — at first.

A Goldilocks zone — usually called a “habitable zone” (HZ) — is the area around a star that has the right temperature and luminosity for a planet to maintain liquid water on its surface. To have an HZ, a star must have a certain minimum temperature at its surface or else any planet near the star will be frozen over, no matter how close in the world orbits. That minimum temperature is roughly 325 kelvins (125° Fahrenheit). This value comes from 273 K (32° F, the freezing point of water) multiplied by the fourth root of two to account for the fact that even a planet placed extremely close to a star is cooler than the star because it re-radiates some of its heat from its night side. I say “roughly” because many details determine the surface temperature of a planet, like whether or not one side of the world always faces its star.

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