Peak CO line fluxes for the red (dots) and blue component (triangles), with the best LVG model (bold and light dashed lines, respectively) computed with a density n_H2 = 3.5 × 10³ cm^-3, T_k = 45 K, and a column density N(CO) = 10¹⁸ cm^-2/ km s^-1. The light dashed line is related to the bold line in a ratio of 0.8 to 1. The color lines represent CO data from other galaxies (e.g. Weiss et al. 2007; Danielson et al. 2011).