Context

• Scientists have discovered the first convincing evidence for a new type of stellar explosion -- an electron-capture supernova.

Supernovae

• A supernova is the explosion of a star. It is the largest explosion that takes place in space.
• A supernova happens where there is a change in the core, or center, of a star.

Categories

• Historically, supernovae have fallen into two main types: thermonuclear and iron-core collapse.
• A thermonuclear supernova is the explosion of a white dwarf star after it gains matter in a binary star system.
• These white dwarfs are the dense cores of ash that remain after a low-mass star (one up to about 8 times the mass of the sun) reaches the end of its life.
• An iron core-collapse supernova occurs when a massive star -- one more than about 10 times the mass of the sun -- runs out of nuclear fuel and its iron core collapses, creating a black hole or neutron star.
• Between these two main types of supernovae are electron-capture supernovae.
• These stars stop fusion when their cores are made of oxygen, neon and magnesium; they aren't massive enough to create iron.
• While gravity is always trying to crush a star, what keeps most stars from collapsing is either ongoing fusion or, in cores where fusion has stopped.
• In an electron capture supernova, some of the electrons in the oxygen-neon-magnesium core get smashed into their atomic nuclei in a process called electron capture.
• This removal of electrons causes the core of the star to buckle under its own weight and collapse, resulting in an electron-capture supernova.

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