Origin of Phaethon’s blue spectral slope

Determine the relative contributions of mineral composition, regolith physical properties, and inherited parent-family characteristics to the blue visual spectral slope of (3200) Phaethon.

Background

(3200) Phaethon exhibits a blue visual spectral slope, but the paper states that its origin cannot be uniquely assigned to mineral composition, physical regolith structure, or inheritance from Phaethon’s parent family. The experiments demonstrate that intense heating can modify brightness and morphology, providing a possible explanation for part of the spectral behavior, but they do not resolve the relative contributions of these competing factors.

References

In addition, Phaethon shows a blue visual spectral slope, for which the relative contributions of its mineral composition, regolith physical properties, and inheritance from its parent family remain uncertain.

— Experimental evidence for physical alteration of fine regolith on near-Sun asteroids  (2610.17652 - Geem et al., 13 Oct 2026) in Section 1, Introduction