2026ApJ...999L..24Z

We report the discovery of a lithium dip (Li dip) in the stellar “Snake” (age = 35 ± 5 Myr), challenging the classical view that Li dips emerge only at ages ≳150 Myr. Using high-resolution spectra from GALAH Data Release 4 (R ∼ 28,000) for 211 member stars, we identify a clear depletion feature in a T_eff range of 6200-6800 K with a depth of ΔA(Li) ≈ 0.40 dex. Our analysis reveals two key advances: the Li dip appears ≳100 Myr earlier than the previous observations, and within the dip temperature range, a significant correlation is found between rotational velocity and lithium depletion. Specifically, fast rotators ($v\sin i\gt 25$ km s^–1) exhibit stronger lithium depletion than slow rotators ($v\sin i\lt 25$ km s^–1). This trend suggests that faster rotators develop stronger rotational shear at the convective-radiative boundary, which enhances turbulent mixing and accelerates lithium destruction. It is also found that the lower temperature edge of the lithium plateau can reach as low as 5500 K for the young open clusters.