Summary of ALMA data of the H30α line (see also Fig. A.3). Top, panel a: integrated spectrum of the H30α line obtained with ALMA (black lines) and with the IRAM-30 m antenna (gray histogram, CSC+17). The colored hatched regions indicate the different velocity intervals used to generate the maps in panels b–d. The ALMA profile multiplied by a factor of 10 (dotted line) is overplotted for a clearer view of the broad line wings. Panels b–d: we show the H30α emission maps integrated over the line wings, the peaks, and the valley, respectively. Bottom: position velocity cuts of the H30α line through the center of MWC 922 along the disk plane (left, PA = 45°) and the perpendicular direction (right). Levels are 2.5, 5, 7.5, 10, 20, and then from 50 to 1700 in steps of 75 mJy beam⁻¹.