## Premain-sequence Evolution

Premain-sequence evolutionary path is understood as follows: Consider a situation that a star with is left when accretion stops. Figure 4.22 indicates that a less-massive star with is fully convective. Thus, this evolves along the convective Hayashi track (Hayashi 1961) down to the main-sequence. In contrast, a massive star with (Fig.4.22) is fully radiative and evolves along the radiative Henyey track (Henyey, LeLevier, & Levee 1955) to the main-sequence. These differences are clearly indicated in Figure 4.24. We can see veritical Hayashi track is seen essentially for stars with . Massive stars with evolve to the upper-left direction along the Henyey track.

Kohji Tomisaka 2012-10-03