Structure and Mass Segregation in h and χ Persei

We use V magnitudes and spectral types to examine the density structure of h and χ Per. We describe an automatic method for deriving spectral types and compare classifications for observations made at two different facilities. With these data, we measure an extinction to the clusters of E(B - V) = 0.52 ± 0.07, consistent with other authors. However, there appears to be a correlation between the spectral types of the stars used and the resulting value of the extinction. We compare extinction values measured by different authors using different numbers of stars and reproduce their values by imposing different cuts in the V magnitude. This variation in color excess versus spectral type suggests that the standard intrinsic colors for the earliest type stars are bluer than the stars in h and χ Per. We measure centers for h and χ Per at α(2000) = 2^h18^m564 ± 30, δ(2000) = 57°8'25'' ± 23'' and α(2000) = 2^h22^m43 ± 29, δ(2000) = 57°8'35'' ± 25'', respectively. We fit the density structure of the clusters and find core radii of 1.9 and 2.4 pc, respectively. Integration of the Miller-Scalo initial mass function suggests overall cluster masses of 5500 and 4300 M_⊙ and central densities of 27 and 50 M_⊙ pc^-3, respectively. We find strong evidence of mass segregation in h Per but not in χ Per. Examination of the dynamical timescales, as well as comparisons between the two clusters, suggest that the mass segregation is partly primordial.