The Geometry of the G29-38 White Dwarf Dust Disk from Radiative Transfer Modeling

Many white dwarfs host disks of dust produced by disintegrating planetesimals and revealed infrared excesses. The disk around G29-38 was the first to be discovered is now well-observed, yet we lack a cohesive picture its geometry properties. Here model for time using radiative transfer calculations that account radial vertical temperature optical depth gradients. We arrive at set models can match available measurements well, although they overpredict width 10 $\mu m$ silicate feature. resulting has inner edge located 92-100 $R_\text{WD}$ (where dwarf radius). This farther from star than inferred previous modeling efforts due presence directly illuminated front disk. narrow ($\leq$10 $R_\text{WD}$); such feature could explained inefficient spreading or proximity tidal disruption radius sublimation radius. have half-opening angle $\geq$1.4$^\circ$. Such structure would in strong contradiction with commonly employed flat-disk analogous rings Saturn, line main-sequence debris disks. Our results are consistent idea collisionally active continuously fed new material, rather evolving passively after disintegration single planetesimal.