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White dwarf
The exposed core a low-mass star leaves behind, Earth-sized and slowly cooling forever.
When a star like the Sun exhausts its fuel it sheds its outer layers and leaves the core: a ball of carbon and oxygen about the size of Earth with the mass of a star, held up not by heat but by the quantum pressure of its own electrons. It produces no new energy and simply radiates away what it has, over billions of years. A white dwarf that steals enough matter from a companion to cross 1.4 solar masses cannot support itself and detonates entirely, which is a Type Ia supernova.
Where it has come up lately
Universe Today
Universe Today
Phys.org
Phys.org
A Pair of White Dwarfs Locked in a Six-Minute Orbit Might One Day Be Observed By Gravitational Waves
Universe Today
Related terms
Magnetar
A neutron star with a magnetic field a thousand trillion times Earth's.
Supernova (Type Ia and Type II)
Two unrelated ways for a star to explode, useful for two entirely different reasons.
The main sequence
The long, stable middle age a star spends fusing hydrogen in its core.
Hertzsprung–Russell diagram
The single plot that organises everything about stars.
Questions
What is White dwarf?
The exposed core a low-mass star leaves behind, Earth-sized and slowly cooling forever.
Why does it matter?
It produces no new energy and simply radiates away what it has, over billions of years. A white dwarf that steals enough matter from a companion to cross 1.4 solar masses cannot support itself and detonates entirely, which is a Type Ia supernova.