(R. z. 5) = n(0,0,S)expl-R/hx(S)lexp[-121/h (5)). (2.8) where he is called the scale length of the disk and h, is the scale height. Figure 2.8 shows that, near the midplane, W, 300-350 pe for K dwarfs, while for more massive and shorter-lived stars, such as the A dwarfs, it is smaller, h. 200 pc. 2.2 The stars in the Galaxy 71 10 stors per (10pc) 0.1 G. K stors 0.01 Astors 1pc 0 height z above disk (koc) Fig. 2.8. Looking toward the south Galactic pole led circles show the density of stars with 5