Mapping Interstellar Dust in the Foreground Outer Disk of Overlapping Galaxy Pair VV 191 with HST and JWST

Abstract VV 191 is a nearby ( z ∼ 0.05), overlapping (occulting) galaxy pair, where a multiple-armed spiral galaxy is backlit by an elliptical galaxy. The overlap is used to derive and map dust attenuation in two James Webb Space Telescope NIRCam filters (F090W and F150W) and one visible-band Hubble Space Telescope Wide Field Camera 3 filter (F606W). We present maps of the attenuation in each filter, the ratio of total to selective attenuation with a near-infrared (NIR) color excess, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>R</mml:mi> </mml:mrow> <mml:mrow> <mml:mover accent="true"> <mml:mrow> <mml:mi>V</mml:mi> <mml:mi>I</mml:mi> </mml:mrow> <mml:mrow> <mml:mo stretchy="true">˜</mml:mo> </mml:mrow> </mml:mover> </mml:mrow> </mml:msub> </mml:math> , and the NIR attenuation curve power-law index, α , approximated via Monte Carlo resampling methods. The maps trace the optically thin outer disk of foreground galaxy VV 191b at ∼100 pc physical resolution. We find the distributions of attenuation and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>R</mml:mi> </mml:mrow> <mml:mrow> <mml:mover accent="true"> <mml:mrow> <mml:mi>V</mml:mi> <mml:mi>I</mml:mi> </mml:mrow> <mml:mrow> <mml:mo stretchy="true">˜</mml:mo> </mml:mrow> </mml:mover> </mml:mrow> </mml:msub> </mml:math> to be close to log-normal, and the distribution of α to be close to Gaussian throughout the disk and in high signal-to-noise ratio areas of VV191b. We analyze three spatially resolved handpicked regions in the far outer disk that are well backlit by the background galaxy.