Contours of CO J = 19–18/CO J = 12–11 ratio overplotted on the CO J = 19–18 emission (left panel). The contours of CO J = 19–18/CO J = 12–11 intensity ratio overplotted on the IRAC 8 μm (right panel). The CO J = 19–18 line intensities are in units of erg s⁻¹ cm⁻² sr⁻¹ and the 8 μm intensities are in units of MJy sr⁻¹. The contours are separated by 1 and cover ratios from 1 to 5.