White Dwarf

A white dwarf is the incredibly dense, slowly cooling remnant of a star that was once similar to our Sun. When stars with masses between 0.5 and 8 times our Sun exhaust their nuclear fuel, they expel their outer layers as spectacular planetary nebulae, leaving behind a hot, compact core roughly the size of Earth but containing about 60% of the Sun's mass. This creates matter so dense that a teaspoon would weigh as much as an elephant on Earth!</p><p>These stellar corpses shine with temperatures reaching 100,000°C initially, appearing brilliant white-hot, hence their name. However, with no internal fusion reactions to sustain them, they gradually fade and cool over billions of years, eventually becoming cold, dark objects. The closest white dwarf, Sirius B, orbits the bright star Sirius and was first observed in 1862, though astronomers had predicted its existence years earlier by studying Sirius's wobbling motion.</p><p>White dwarfs are supported against gravitational collapse by electron degeneracy pressure—a quantum mechanical effect that prevents further compression. They represent the fate awaiting our own Sun in about 5 billion years. These cosmic time capsules also serve as precise "cosmic clocks," helping astronomers determine the ages of star clusters and galaxies by measuring how much they've cooled since formation.