White Dwarf Stars

A scale compilation of several known white dwarf stars. For explanation of what a white dwarf is, please see here: en.wikipedia.org/wiki/White_dw…

Some notes:
- Despite the name, white dwarfs are not all white. Their color is a function of their temperature. Cooler stars are more orange and hotter ones are more blue. In order to figure out what color these stars would be in reality, I used this website as a guide: www.vendian.org/mncharity/dir3…
- The mass unit "solar" is a measure of how heavy the star is compared to the Sun. For example, a mass of 0.98 solar means that the star is 98% as heavy as our Sun. The heaviest that a white dwarf star can be is about 1.39 solar masses, above which it will collapse into a neutron star or black hole.
- Since white dwarf stars are similar in size to planets (despite having masses comparable to the Sun), they are extremely dense (around a billion kilograms per cubic meter).
- Where there is a (DA) in the star name, that is simply to designate that this is the white dwarf of a multiple star system, where all the stars within the system may otherwise share the same designation or name with each other.
- As a general rule, white dwarf stars become smaller as they grow in mass, the opposite of what one would expect.
- White dwarf stars have no internal mechanism for generating heat (no nuclear fusion), so they are at their hottest when they first form. Over time, they cool off by emitting radiation into space. Older white dwarfs are generally cooler than younger white dwarfs for this reason. PG 1159-035, with a blazing surface temperature of 136,000 Kelvins, is a young, "pre-degenerate" star that is in transition to becoming a true white dwarf. A white dwarf designated RX J0439.8-6809 is the hottest known white dwarf star, at 250,000 Kelvins.
- The Earth is provided for size comparison.
- PSR J2222-0137 (DA) is also known as the "Diamond Star" because it is thought to be cool enough to crystallize into degenerate carbon. Despite what you may read in news articles, however, this is not true diamond, as it is far, far more dense. As another note, I was unable to find any radius figures for this star, but news articles repeatedly referred to it as "Earth-sized" so I used that as the baseline radius for this diagram.
- Sirius B is both the first white dwarf to be discovered (in 1852) and the closest to Earth (8.6 light-years).