What process supports the core of a Sun-like star during the Horizontal Branch phase after the helium flash?

Answer

Electron degeneracy pressure

For stars similar to the Sun, the contracting helium core becomes supported by electron degeneracy pressure while it actively fuses helium into carbon and oxygen during the Horizontal Branch phase.

What process supports the core of a Sun-like star during the Horizontal Branch phase after the helium flash?
evolutionprocessstarFusion