RADEX analysis of the ³⁴SO₂ line ratios toward zone A and B assuming a FWHM line width 5.0 km s^-1. The intensity ratios 19_1,19 − 18_0,18/10_4,6 − 10_3,7 are plotted in color scale. The observed integrated intensities of the 19_1,19 − 18_0,18 transition are plotted in curves (zone A: ~63 Jy beam^-1 km s^-1, zone B: ~15 Jy beam^-1 km s^-1). Toward both zones, the line ratio is about 1.8 (Table 3). Our results suggest that a high H₂ volume density (> 10⁹ cm^-3) is needed to reproduce the observed line ratios.