Results of the radiative transfer modeling with XCLASS of the CH₃CN (12_K – 11_K, K = 0– 6) data. The maps cover 2.2′′ × 2.2′′ extracted around the two major cores MMS1a and b, where pixels with flux below were blanked out. The black contours indicate the 5, 10, 15, 20σ continuum emission levels and increase further in steps of 20σ, where σ = 0.28 mJy beam⁻¹. The black diamonds in the MMS1a panel mark the positions of the emission peaks at 3.6 cm (Rodríguez et al. 2012). The shaded ellipse in the lower right corner indicates the synthesized beam of the CH₃ CN data of 0.42′′ × 0.35′′ (PA 61°). Details to the spectral line map fit are summarized in Sect. 3.5. Top: rotational temperature maps from XCLASS. Middle: H₂ column density maps, estimated from the continuum intensity I_ν (Fig. 1), and rotational temperature T_rot (top panels) using Eq. (2). Bottom: velocity offsets from XCLASS. The colors indicate the relative velocity with respect to the v_LSR = −53.1 km s⁻¹. In the MMS1b panel, the additional black diamonds mark the positions of the H₂ O masers with the corresponding velocity in km s⁻¹ from Rodríguez et al. (2012). The M1 maser group contains maser emission with velocities ranging from − 37.2 to − 66.8 km s⁻¹. The blue and red arrows are the outflow axes as in Fig. 6. The solid and dashed black arrows are the cut directions for the PV diagrams presented in Fig. 9, along the presumable disk semi-major axes.