Upper panel: spectral line and LTE model of the HCN (3–2) line obtained from LTE-MCMC calculations assuming T_exc = 150 K (see text), with a resulting density of N = (1.9 ± 0.5) × 10¹⁴ cm⁻². The blue line indicates the residual obtained from the subtraction between the observation and LTE model. In colors: spatial distribution of the HCN (3–2) emission in the velocity interval from −47.6 to −29.2 km s⁻¹ (color blue and white contours) superimposed on the IRAC 8 and 5.8 μm emissions (red and green colors). Lower panel: same as above for the HCO⁺ (3–2) line, assuming T_exc = 50 K, with a resulting density of N = (5.2 ± 0.1) × 10¹³ cm⁻². The HCO⁺ (3–2) emission distribution is in the velocity interval from −44.8 to −32.5 km s⁻¹. The contour levels for the HCN (3–2) are 0.25 (~5 rms), 0.85, 2.2, and 4.0 K km s⁻¹; and for the HCO⁺ (3–2) line, they are 0.28(~5 rms), 0.8, 2.4, and 5 K km s⁻¹