In Norse mythology’s Ragnarok, the sun’s surviving daughter is unnamed in the main surviving sources. Völuspá says that before the wolf catches the sun, she bears a daughter who travels the mother’s path after the gods die.
The sun itself is personified as Sól, and the daughter’s continuation preserves the cosmic cycle after the world’s destruction. Unlike Sól, the daughter is not given a personal name in the relevant Ragnarok passages. Some modern retellings supply names or treat poetic bynames as if they were distinct characters, but those additions are not secure in the primary account.
This detail is different from asking which body replaces the sun. The important fact is that a daughter survives and follows the same celestial course, allowing light to continue in the restored world.