What characteristic fundamentally predetermines the energy output and lifespan of a stable star?

Answer

The amount of mass condensed from the nebula.

The initial mass accumulated by the collapsing cloud dictates the required core temperatures and pressures, thus determining the star's energy consumption rate and its total lifespan on the Main Sequence.

What characteristic fundamentally predetermines the energy output and lifespan of a stable star?

#Videos

6.2.2 The Formation of Stars - GCSE & IGCSE Physics - YouTube

GCSE Physics - The Life Cycle Of Stars / How Stars are Formed and ...

physicsstabilitystarformationIGCSE