What characteristic fundamentally separates a white dwarf from an active main-sequence star?

Answer

Sustained core nuclear fusion

The consensus reason white dwarfs forfeit the title of 'true star' is the lack of sustained core fusion, marking them as energetic remnants rather than living, fusing objects.

What characteristic fundamentally separates a white dwarf from an active main-sequence star?

#Videos

Are white dwarfs stars -- a debate! - YouTube

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