Context: An exciting pair of white dwarf stars spiralling in towards one another has became the latest addition to a pool of gravitational wave sources
- Stars come in all sizes. There are small stars that are much smaller than our sun. Then there are supermassive stars several times the size of the sun. Our own galaxy Milky Way hosts a number of such stars.
- A white dwarf is what stars like the Sun become after they have exhausted their nuclear fuel.
- Near the end of its nuclear burning stage, this type of star expels most of its outer material, creating a planetary nebula. Only the hot core of the star remains
- This core becomes a very hot white dwarf, with a temperature exceeding 100,000 Kelvin.
- Unless it is accreting matter from a nearby star (see Cataclysmic Variables), the white dwarf cools down over the next billion years or so.
- Many nearby, young white dwarfs have been detected as sources of soft, or lower-energy, X-rays. Recently, soft X-ray and extreme ultraviolet observations have become a powerful tool in the study the composition and structure of the thin atmosphere of these stars.
- A typical white dwarf is half as massive as the Sun, yet only slightly bigger than Earth.
- White dwarf binaries contains two white dwarfs with helium cores, swirling shockingly close, but not sharing any matter
- white dwarf binaries with particularly tight orbits, such as this new discovery, can become a source of gravitational waves: invisible ripples in the fabric of space-time, generated as extremely massive objects change their speed.