White Dwarf Stars

White Dwarfs

Stars are usually measured in comparison with our Sun's mass. A star whose remaining mass is about that of our Sun condenses to approximately the size of Earth.

The star's contraction is halted by the collective resistance of electrons pressed against each other and their atomic nuclei. Matter in this collapsed star is so tightly packed that a piece the size of a sugar cube would weigh thousands of kilograms. Gravitational contraction would also have made the star white hot. It is appropriately called a white dwarf.

Astronomers have detected white dwarfs in space. The first discovery was a planet-sized object that seemed to exert a disproportionately high gravitational effect upon a celestial companion, the so call dog star Sirius, which is about 2.28 times our Sun's mass.

It appeared that this planet-sized object would have to be about as massive as our Sun to affect Sirius as it did. Moreover, spectral analysis indicated the star's color was white.

Based upon these and other studies, astronomers concluded that they had found a white dwarf. However, it took many years after the discovery in 1914 before most scientists accepted the fact that an object thousands of times denser than anything possible on Earth could exist.