Gas velocity of the circumbinary disk. Left: ¹³CO J = 3–2 velocity map performed using the intensity weighted method, and subtracted by the systemic velocity of 3.73 km s⁻¹. Contours are displayed from −2.75 to 2.75 km s⁻¹ and are spaced by 0.5 km s⁻¹. Right: blue- and redshifted velocities (indicated by blue and red colors) along the line-of-sight compared to the Keplerian rotation, as expressed by Eq. (1). A polar ellipse represented by a black solid line denoted (1) indicates the potential presence of a anticyclonic vortex, and three spiral-like structures in black dotted-line denoted (2), (3), and (4) are superimposed.