Figure 18-12: Main-Sequence Stars of Different Masses Stellar models show that when a protostar evolves into a main-sequence star, its internal structure depends on its mass. Note: The three stars shown here are not drawn to scale. Compared with a 1-M_⊙ main-sequence star like that shown in (b), a 6-M_⊙ main-sequence star like that in (a) has more than 4 times the radius, and a 0.2-M_⊙ main-sequence star like that in (c) has only one-third the radius.