Tidal disruption radius R _T (scaled by the BH gravitational radius R _g ) of Pop III stars and a solar-type star as a function of BH mass M _BH. The red and blue solid or dashed lines represent Pop III stars of mass 300M _⊙ (M ₃₀₀) and 30M _⊙ (M ₃₀), respectively, with metallicity Z = 10⁻⁵ (Z ₋₅) or 10⁻⁹ (Z ₋₉). The black solid line shows a solar-type star for comparison. It can be seen that a Pop III star, depending on its metallicity, has a R _T similar to or a few times larger than that of the Sun. The green dotted line indicates R _T = R _g , which gives the maximum mass of M _BH for a star to be disrupted inside the MBH event horizon.