Figure 20

Figure 20: Metric coefficient $R (r)$ for the Janis–Newman–Winicour metric. For $1 < γ < 1 2$ , $R (r)$ is similar to the Schwarzschild case $γ = 1$ (see Figure 9). For $1 γ ≤ 2$ , $R(r)$ has no longer a minimum, i.e., there is no longer a light sphere which can be asymptotically approached by light rays.