Discovery of Photodissociation Region in Overlapping Galaxy Pair VV 191 with HST and JWST

Abstract We present a photodissociation region (PDR) found ∼17 kpc from the galaxy center in the outer disk of the foreground spiral galaxy of partially overlapping—occulting—galaxy pair VV 191 at z ∼ 0.05. Dust attenuation in foreground galaxy, VV 191b, is derived using backlighting by the superimposed background elliptical galaxy VV 191a. Imaging with the James Webb Space Telescope (JWST) and the Hubble Space Telescope span the wavelength range 0.3–4.5 μ m at ∼100 pc scales resolution. We observe this PDR by isolating the 3.3 μ m aromatic infrared band using the JWST F356W and F444W filters and analyzing the dust attenuation and reddening surrounding the PDR cavity. Results show a spiral-arm like dust cavity surrounding the PDR with visual evidence of 3.3 μ m polycyclic aromatic hydrocarbon emission around the strong ultraviolet emission associated with O and B stars.