H¹³CO⁺ integrated intensity maps toward IRS3B over a selected range of velocities overlaid on continuum (gray scale). The top row spatial scale is set to match those of Figure 4, and the bottom row scale is set to encapsulate the entire IRS3B system, to better demonstrate the spatial scales probed with this molecule. The top row is tapered with a 400 kλ Gaussian to best reduce the amount of noise and show the proper resolution to the spatial scales shown. The H¹³CO⁺ emission is primarily tracing the intermediate dense, gaseous material within the inner envelope, but the higher-velocity emission does originate near the protostars. The columns correspond to similar velocity ranges of C¹⁷O emission as shown in the previous figure, with low, medium, and high Doppler-shifted velocity ranges delineated as red (blue). Negative contours do not show additional structure and are suppressed for visual aid. The red lines indicate the region extracted for PV diagram construction, along the position angle of the major axis in a region much larger than the C¹⁷O PV diagram extraction to fully capture the emission. Low velocity: velocity ranges 4.7 ﹩\to ﹩ 5.7 km s⁻¹ (3.6 ﹩\to ﹩ 4.7 km s⁻¹), contours start at 10σ (10σ) and iterate by 2σ (2σ) with the 1σ level starting at 0.003 (0.003) Jy beam⁻¹ for the top row and 0.005 (0.005) Jy beam⁻¹ for the bottom row, red (blue) channels. Medium velocity: velocity ranges 5.7 ﹩\to ﹩ 6.7 km s⁻¹ (2.4 ﹩\to ﹩ 3.5 km s⁻¹), contours start at 5σ (5σ) and iterate by 5σ (3σ) with the 1σ level starting at 0.005 (0.005) Jy beam⁻¹ for the top row and 0.005 (0.005) Jy beam⁻¹ for the bottom row, red (blue) channels. High velocity: velocity ranges 6.7 ﹩\to ﹩ 7.7 km s⁻¹ (1.3 ﹩\to ﹩ 2.4 km s⁻¹), contours start at 5σ (5σ) and iterate by 2σ (2σ) with the 1σ level starting at 0.002 (0.002) Jy beam⁻¹ for the top row and 0.005 (0.005) Jy beam⁻¹ for the bottom row, for the red (blue) channels. The H¹³CO⁺ synthesized beam (top: 0.″374 × 0.″310, bottom: 0.″85 × 0.″52) is the bottom rightmost ellipse on each of the panels, and the continuum synthesized beam (0.″11 × 0.″05) is offset diagonally.