Line strengths of two CO transitions as a function of Ṁ_g/ ν_∞,g: CO J = 15−14 on the left and CO J = 30−29 on the right. The points with error bars give the measured CO line strengths, color coded according to the variability type. A black cross superimposed on the data point indicates that the CO line is flagged as a blend. The colored curves show the predicted CO line strength for various values of the temperature power law exponent ϵ. Adopted values for other parameters are listed in Table 4. The line strengths are scaled to a distance of 100 pc.