Spectral profiles of emission lines arising from hot molecular gas in the surroundings of the HC HII region. The spectra shown are integrated toward the dust continuum sources W51e2-E (top row), W51e2-NW (middle row), and toward the entire molecular core seen in emission (bottom row), respectively. Left and central panels: spectral profiles of NH₃  for transitions (6, 6), (7, 7), (9, 9), (10, 10), and (13, 13). An offset in flux density is applied to transitions adjacent in energy to better display individual profiles. The lower state energy levels of transitions shown here are ~ 408−1691 K (see Table 1). The hyperfine satellite lines, separated by ~ ± 24−31 km s^-1 (see Table 3), are clearly detected for the (6, 6), and (7, 7) doublets in the three cases; the (9, 9) HF lines are detected only toward W51e2-E (top row, left panel). A narrower velocity range is plotted in the central panel to show the profiles of the main hyperfine component of each inversion transition more clearly. Right panel: spectral profile of the J_K = 13₂–13₁ line of CH₃OH (ν_rest = 27.473 GHz). The velocity resolution is 0.4 km s^-1 (all panels), and the vertical dashed line in the central and right panels indicate velocities of 56.4 km s^-1 (top row), 55.2 km s^-1 (middle row), and 55.3 km s^-1 (bottom row), respectively.