A white dwarf below 1.44 solar mass in a binary system may accrete mass from its companion. If its core reaches the temperature for carbon fusion during this process, the white dwarf may reignite in a runaway fusion. The runaway fusion could release sufficient energy to unbind the white dwarf in a type Ia supernova. An earlier answer mentioned that the star is completely destroyed in a type Ia supernova.

Since the degenerate matter in the core of the white dwarf is the result of the gravitational compression, what becomes of the degenerate matter once the white dwarf is unbound?

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    $\begingroup$ It reverts to normal matter. (Very hot, expanding normal matter.) $\endgroup$ Feb 2, 2023 at 22:25
  • $\begingroup$ @PeterErwin I take it would be anything between hydrogen and iron? $\endgroup$
    – Mys_721tx
    Feb 2, 2023 at 22:31
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    $\begingroup$ @Mys_721tx Even greater than iron, and not so much hydrogen. See, for example, apod.nasa.gov/apod/ap230108.html . $\endgroup$ Feb 3, 2023 at 0:25

1 Answer 1


It becomes part of the interstellar medium.

The carbon and oxygen is almost entirely fused into heavier elements and dispersed. This is the process by which much of the iron, nickel, manganese and some other elements (Si, S, Ar, Ca) come to be relatively abundant in stars formed in the last 10 billion years.


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