Final answer:
A typical white dwarf is a star that has about the Sun's mass but is only as large as Earth, with an extremely high density. They are the last evolutionary stage of stars like our Sun after becoming red giants, and before finally ending their life cycle.
Step-by-step explanation:
A typical white dwarf is as massive as the Sun but only about as large in size as Earth. Specifically, a common white dwarf like 40 Eridani B has a mass approximately 0.57 times that of the Sun and a radius that is only about 1.4% of the Sun's radius. These stars are incredibly dense, with a density about 210,000 times the density of the Sun, equating to more than 300,000 g/cm³. It's fascinating to note that a teaspoonful of white dwarf material would weigh roughly 1.6 tons due to this extreme density.
During their life cycle, stars like our Sun will eventually become red giants before transitioning to white dwarfs. Interesting contrasts are inherent between these two evolutionary stages, such as the fact that a white dwarf's temperature can reach approximately 25,000 K, whereas a red giant may have a much cooler surface temperature of about 3,000 K, yet it has a radius nearly 100,000 times larger than a white dwarf.
Additionally, the study of white dwarfs reveals the unique evolutionary paths of stars based on their initial masses, as demonstrated by the observation that a star initially more massive than its companion Sirius could evolve into a white dwarf earlier. This highlights the diversity in stellar lifetimes and endpoints based on their initial mass and other factors.