$\star$ Correlation enters the residuals and the color

Figure 10.8 shows the correlation between the color and the residuals to the diagram of Hubble for $\beta = 0$. This correlation indicates to us that the reddest supernovæ (with B-v largest) are also the least luminous. This is in agreement with the laws of extinction which we observe. This correlation will enable us to correct during the adjustment the extinction apart from our Galaxy (by dust along the line of sight and galaxy host).

Figure 10.8: Correlation enters the residuals of the diagram of Hubble out of B and the color to the maximum.