JWST Imaging of Edge-on Protoplanetary Disks. V. Flux Ratio Reversal and Disk-edge Structure in the Flying Saucer

Résumé : We present near- and mid-infrared broadband imaging observations of the edge-on protoplanetary disk 2MASS J16281370-2431391, a.k.a. the 'Flying Saucer', obtained with NIRCam and MIRI on board JWST. These data are combined with archival optical and near-IR broadband imaging from HST, millimeter dust continuum emission from ALMA, and optical lightcurves from the K2 and TESS for a comprehensive multi-wavelength study. The JWST observations reveal a reversal of the flux ratio between the two reflection nebulae at near-infrared wavelengths (2-3 $μm$), which can be explained by a misaligned inner disk. For the first time, JWST reveals the bright lining along the disk edge at 2 and 3 $μm$, arising from forward scattering of background photons by dust grains near the $τ\approx 1$ layer. By combining the dust lane thickness measured with HST and JWST, we find the dust grains up to at least $\sim$3$μ$m are vertically mixed throughout the disk and have undergone significant growth. In addition, comparison of earlier HST/NICMOS J and K band images with those from JWST/NIRCam reveals variability in the scattered-light morphology, as well as measurable proper motion of the system with respect to the background stars, confirming that the Flying Saucer is co-moving with the young star population of $ρ$ Ophiuchi.