Tidal Stripping as the Driver of Mass Segregation in the Young Open Cluster NGC 2422

Abstract We present strong evidence that mass segregation in the young open cluster NGC 2422 (age ≈84 Myr) is primarily driven by tidal stripping. Analysis of the radial mass distribution reveals a significant overabundance of low-mass stars ( M < 0.85 M ⊙ ) preferentially located near and beyond the cluster’s tidal radius ( r t = 14.4 pc), a hallmark of ongoing tidal stripping. This spatial signature is corroborated by kinematic evidence: the cluster’s outskirts exhibit an elevated velocity dispersion ( σ 3d = 14.9 km s −1 , F-test p < 0.001) and strong radial anisotropy ( β = 0.94 ±0.4), both classic signatures of tidal influence. The cluster’s age is significantly greater than its half-mass relaxation time ( t rh = 44.2 Myr), confirming it is dynamically evolved. Crucially, binary stars show no significant radial segregation from single stars (KS-test p ≈ 0.51), ruling them out as the primary driver. Collectively, these results establish tidal stripping as the dominant mechanism currently reshaping the structure and stellar content of NGC 2422.