Similar to Figure 1, but now with rotation periods computed from B − V using Equation (2) and the assumption that M67 is 4 Gyr old. (The green symbols would end up further to the left if we assumed instead an age of 5 Gyr.) Here all stars are included—not just those for which ﹩{P}_{\mathrm{rot}}﹩ would also be available; see Table 1. The inset shows ﹩\tau /{P}_{\mathrm{rot}}^{* }﹩ as a function of B − V using Equation (3). The data points for the stars of M67 are overplotted to illustrate the scatter and the range in B − V covered by the data. The red dotted line without surrounding data points shows the result using the gyrochronology relation of Barnes (2010) and Barnes & Kim (2010) for ﹩\tau (B-V)﹩, denoted by B+BK.