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

Nicholas P. Ballering, Colette I. Levens, Kate Y.L. Su, L. Ilsedore Cleeves

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Many white dwarfs host disks of dust produced by disintegrating planetesimals and revealed by infrared excesses. The disk around G29-38 was the first to be discovered and is now well-observed, yet we lack a cohesive picture of its geometry and dust properties. Here we model the G29-38 disk for the first time using radiative transfer calculations that account for radial and vertical temperature and optical depth gradients. We arrive at a set of models that can match the available infrared measurements well, although they overpredict the width of the 10 μm silicate feature. The resulting set of models has a disk inner edge located at 92-100 R WD (where R WD is the white dwarf radius). This is farther from the star than inferred by previous modeling efforts due to the presence of a directly illuminated front edge to the disk. The radial width of the disk is narrow (≤10 R WD); such a feature could be explained by inefficient spreading or the proximity of the tidal disruption radius to the sublimation radius. The models have a half-opening angle of ≥1.°4. Such structure would be in strong contradiction with the commonly employed flat-disk model analogous to the rings of Saturn, and in line with the vertical structure of main-sequence debris disks. Our results are consistent with the idea that disks are collisionally active and continuously fed with new material, rather than evolving passively after the disintegration of a single planetesimal.

Original languageEnglish (US)
Article number108
JournalAstrophysical Journal
Issue number2
StatePublished - Nov 1 2022

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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