u/Moist_Spring

In the game Helldivers 2, the planet Ivis was torn apart by the gravity of a black hole passing near to its star system. This took place a year ago, and the insides of the planet are still glowing hot. If a planet like Earth was ruptured into pieces that stuck somewhat close together like in the screenshot, how long would it take for the core and mantel to cool down enough to stop producing light?