Suppose that a white dwarf is gaining mass through accretion in a binary system. what happens if the mass someday reaches the 1.4 solar mass limit? suppose that a white dwarf is gaining mass through accretion in a binary system. what happens if the mass someday reaches the 1.4 solar mass limit? the white dwarf will collapse to become a black hole. the white dwarf will undergo a nova explosion. the white dwarf will collapse in size, becoming a neutron star. the white dwarf will explode completely as a white dwarf supernova.

The white dwarf will explode completely as a white dwarf supernova.

Explanation:

When a white dwarf gains mass to the Chandrasekhar limit of 1.44 solar masses, it would begin to collapse and, in a few seconds, the matter in the white dwarf will undergo nuclear fusion, and will become in a supernova.  

Only when the core of the white dwarf is composed of neon, magnesium, and oxygen, the gaining mass to 1.44 solar mass, will result in a neutron star.      

Therefore, the answer is the white dwarf will explode completely as a white dwarf supernova.              

I hope it helps you!                

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