Cartoon of 3D structure of the ρ Oph-A cloud where we assume that the cloud has a spherical shape but is pushed by radiation feedback from a nearby high-mass star Oph-S1, shown at the top (left panel, see text) and a plane of the constant coordinate y with the LOS $\hat{z}$ (right panel). Bottom row displays the map of the depth of the cloud, W (left panel), and the map of the gas volume density $\left(n_{{\mathrm{H}}_2}\right)$ inferred from $N_{{\mathrm{H}}_2}$ (right panel). In each panel, the “×” and star symbols mark the peak position of $N_{{\mathrm{H}}_2}$ and location of Oph-S1 star, respectively. Toward maps of W and $n_{{\mathrm{H}}_2}$ in bottom panels, the black dashed circle has a radius R_cl=120″ and black solid contours show the continuum emission at 154 μm with levels similar as shown in Fig. 4.