Final answer:
The correct order is: c) Accretion of matter from the companion star, d) Ignition of carbon fusion, b) Gravitational collapse, and finally a) Explosion and ejection of outer layers. This sequence outlines the transformation from a white dwarf accreting mass in a binary system to the explosive end as a type Ia supernova.
Step-by-step explanation:
The steps in the evolution of a low-mass star in a binary system that leads to a type Ia supernova can be placed in the following order, from earliest to latest:
- Accretion of matter from the companion star. The white dwarf begins to attract material from its companion star, which may also be a red giant at this stage.
- Ignition of carbon fusion. Once enough matter has been accumulated and the conditions are right, carbon fusion ignites in the dense and hot core of the white dwarf.
- Gravitational collapse. The intense pressure and heat from the fusion can push the star over the Chandrasekhar limit, leading to a collapse.
- Explosion and ejection of outer layers. The collapse triggers a supernova explosion, which results in the ejection of the star's outer layers and leaves behind a dense core or nothing at all depending on the mass of the white dwarf.
The process by which a white dwarf acquires mass from its companion star until it reaches the Chandrasekhar limit and subsequently explodes as a supernova is a critical concept in understanding binary system evolution and stellar death.