2D KDE of the entire observed sample in the sHRD (background). The solid lines show the evolutionary tracks of Brott models at 20 M_⊙, 25 M_⊙, 30 M_⊙, 35 M_⊙, 40 M_⊙, 50 M_⊙, 60 M_⊙, 80 M_⊙, and 100 M_⊙ with an initial rotational velocity of 200 km s⁻¹. The dotted lines divide the MS into quarters, determined by the fraction of the initial core hydrogen mass fraction that has been burned. The white line indicates log g = 3.7 dex. Only stars to the left of this line were used to create the initial velocity KDE discussed in Section 4.2.