Second Generation Planet Formation in Post-AGB Discs - II: Dust Coagulation and Core Accretion
Abstract
Observations have established that the circumbinary discs formed around post-asymptotic giant branch (post-AGB) binaries have striking similarities to protoplanetary discs around young stars. In this study, we examine the feasibility of the different stages of growth in the core accretion framework of planet formation in post-AGB discs, in order to assess whether planet formation is possible in these systems. We find that dust coagulation up to mm sizes is possible within the lifetimes of post-AGB discs, consistent with observations. We then investigate the subsequent growth of planetesimals through pebble and planetesimal accretion. If the streaming instability operates in these discs, the resulting planetesimals formed in higher-mass post-AGB discs (Mdisc∼0.1M⊙) can enter rapid pebble accretion and reach their isolation mass within the estimated disc lifetime. By contrast, in lower-mass post-AGB discs (Mdisc∼0.01M⊙), planetesimal accretion is too inefficient to produce substantial further growth. We also show that the larger aspect ratios of post-AGB discs compared to protoplanetary discs around young stars imply high pebble isolation masses and therefore potential formation of rocky planets with masses extending up to Jupiter masses. After assessing gas accretion and concurrent migration in these discs, we conclude that second generation planet formation in post-AGB discs is theoretically possible within their estimated lifetimes (104--105yr) provided that local dust-to-gas ratio enhancements and sufficiently high disc masses are achieved.
Related
- Discovery of a second-generation planet candidate accreting onto a white dwarf
- Scaled three-dimensional simulations of giant-planet accretion and disk clearing
- On the Orbital Evolution of Giant Planet Pair Embedded in a Gaseous Disk. III. simultaneous gas accretion and the final mass ratio
- Signatures of rocky debris accretion in AF-Type planet hosts
- Searching for Embedded Protoplanets with the Keck/NIRC2 Vortex Coronagraph: Confirmation of a Core-accretion Planet in the Narrow Gap of the Elias 2-24 Disk
BibTeX
@misc{pourmand2026second,
title = {{Second Generation Planet Formation in Post-AGB Discs - II: Dust Coagulation and Core Accretion}},
author = {Ali Pourmand and Orsola De Marco and Devika Kamath and Daniel J. Price},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.14816},
eprint = {2609.14816},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.14816},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Second Generation Planet Formation in Post-AGB Discs - II: Dust Coagulation and Core Accretion
AU - Ali Pourmand
AU - Orsola De Marco
AU - Devika Kamath
AU - Daniel J. Price
PY - 2026
DA - 2026/09/13
PB - arXiv
DO - 10.48550/arxiv.2609.14816
UR - https://arxiv.org/abs/2609.14816
AB - Observations have established that the circumbinary discs formed around post-asymptotic giant branch (post-AGB) binaries have striking similarities to protoplanetary discs around young stars. In this study, we examine the feasibility of the different stages of growth in the core accretion framework of planet formation in post-AGB discs, in order to assess whether planet formation is possible in these systems. We find that dust coagulation up to mm sizes is possible within the lifetimes of post-AGB discs, consistent with observations. We then investigate the subsequent growth of planetesimals through pebble and planetesimal accretion. If the streaming instability operates in these discs, the resulting planetesimals formed in higher-mass post-AGB discs (M_disc∼0.1M_⊙) can enter rapid pebble accretion and reach their isolation mass within the estimated disc lifetime. By contrast, in lower-mass post-AGB discs (M_disc∼0.01M_⊙), planetesimal accretion is too inefficient to produce substantial further growth. We also show that the larger aspect ratios of post-AGB discs compared to protoplanetary discs around young stars imply high pebble isolation masses and therefore potential formation of rocky planets with masses extending up to Jupiter masses. After assessing gas accretion and concurrent migration in these discs, we conclude that second generation planet formation in post-AGB discs is theoretically possible within their estimated lifetimes (10^4--10^5yr) provided that local dust-to-gas ratio enhancements and sufficiently high disc masses are achieved.
ER -