Best-fit geometrical models (panel a) flattened ring (Red. χ²  ∼ 10) and (panel b) binary (Red. χ²  ∼ 12)) compared with the observed visibilities (V²) and closure phases of PDS 27. The black points with vertical error bars are the observed data, and the blue triangles correspond to a representative best-fit model. The two models show a similar fit, and therefore we show model b as a representative fit.