Abstract
Aims. Edge-on discs offer a unique opportunity to probe radial and vertical dust and gas distributions in the protoplanetary phase. This study aims to investigate the distribution of micron-sized dust particles in the Flying Saucer in Rho Ophiuchi by leveraging the unique observational conditions of a bright infrared background that enables the edge-on disc to be seen in both silhouette and scattered light at specific wavelengths. Methods. We used NIRSpec IFU observations from the JWST Edge-on Disc Ice program (JEDIce) of the Flying Saucer serendipitously observed against a Polycyclic Aromatic Hydrocarbons-emitting background to constrain the dust distribution and grain sizes via radiative transfer modelling. Results. The observation of the Flying Saucer in silhouette at 3.29 mu m reveals that the midplane radial extent of small dust grains is similar to 235 au, i.e. larger than the large-grain disc extent previously determined to be 190 au from millimetre data. The scattered light observed in emission probes micron-sized icy grains at large vertical distances above the midplane. The vertical extent of the disc silhouette is similar at visible, near-IR, and mid-IR wavelengths, corroborating the conclusion that dust settling is inefficient for grains as large as tens of microns, both vertically and radially.