The fusion of helium formed an inert core of carbon and oxygen.

All but a small fraction of the hydrogen envelope was driven away from the star, leaving behind a white dwarf remnant composed primarily of the inert core.

During helium fusion, stars build up an inert core rich in carbon and oxygen.

The inert core eventually reaches sufficient mass to collapse due to gravitation, whilst the helium burning moves gradually outward.

The photino birds swept, oblivious, through the shining fusion shell and on into the inert core itself.

The inert core has steadily got more massive - contracting, and heating up.

Because they tend to act like an inert core with simply one electron around them, and only that electron excites.

With the neon-burning process an inert core of O-Mg forms in the centre of the star.

The fuel, by omitting Zircalloy sheathing (allowed due to the inert, non-aqueous core) was made far less expensive.

Red giants all have inert cores with hydrogen-burning shells: concentric layers atop the core that are still fusing hydrogen into helium.