WHITE DWARF

Description

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Context

An international team has reported a unique phenomenon in a white dwarf about 1,400 light years from Earth.

About

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.
The white dwarf then 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.
An Earth-sized white dwarf has a density of 1 x 109 kg/m3.
Earth itself has an average density of only 5.4 x 103 kg/m3.
That means a white dwarf is 200,000 times as dense.
This makes white dwarfs one of the densest collections of matter, surpassed only by neutron stars.

Note: A typical white dwarf is half the size of our Sun and has a surface gravity 100,000 times that of Earth. Using the Hubble Space telescope and Transiting Exoplanet Survey Satellite (TESS), astronomers have identified several white dwarfs over the years.

Composition