Compact ¹²CO (J=2−1) absorption feature observed toward the central regions of M 2-9. Top: integrated intensity map of the CO absorption in the velocity range V_LSR=[77.25:83.6] km s⁻¹. Dashed and solid lines are used for negative and positive contours, respectively. Level spacing is 2σ to −13σ by −2σ (σ=4 mJy/beam). The yellow arcs represent the outer boundary of the broad-waist structure, plausibly a compact dust disk, observed in the 1 mm continuum maps. Bottom: line profile integrated over the area where CO absorption is observed.