Welcome to PA3Py’s documentation!

PA3Py (Pebble Accretion 3 in Python) is a post-processing framework for computing the growth and composition of planetary embryos via pebble accretion on top of TripodPy hydrodynamic disk simulations. It is not a standalone disk evolution code — it reads TripodPy HDF5 snapshots and integrates embryo growth over the fully evolved gas and dust structure, including structured disks with planet-carved gaps and pressure bumps.

The pebble accretion physics follows Ormel (2017) and Drążkowska et al. (2023) — headwind/shear regime switching, 2D–3D turbulence transition, Safronov ballistic onset, and a dynamic isolation mass cap (Lambrechts & Johansen 2014). The water snowline migrates following the radiative disk models of Oka et al. (2011) coupled to the Hartmann et al. (1998) stellar accretion-rate decay, and the chemistry module is fully composition-agnostic: any number of species and radial zones can be injected as a plain Python function.

PA3Py was developed as part of the undergraduate thesis “Regulación del Flujo de Pebbles por Subestructuras en Discos Protoplanetarios: Implicancias para el Crecimiento Planetario y la Formación de Waterworlds” at the Instituto de Astrofísica, Pontificia Universidad Católica de Chile.

Contents:

• Pebble Accretion 3 (PA3Py)
  • 1. Critical Mass for Pebble Accretion Onset (Onset Mass)
  • 2. Dynamical Accretion Equations
  • 3. Analytical Transition to a 3D Disk
  • 4. Regulatory Isolation Mass
  • 5. Consumption and Drift
  • 6. Planetary Composition (Physical Tracking)
• 1. Getting Started with PA3Py
  • Initializing the Simulation
  • Running Growth
  • Plotting Mass Evolution
  • Water Mass Fraction
  • Bonus: Multiple Embryos at Once
• 2. Advanced Chemistry (Dynamic Zones)
  • Custom Composition Function
  • Running Custom Chemistry
  • Visualizing Multi-Species Composition
• 3. Synthetic Populations and HDF5 I/O
  • Plotting the Hovmöller Diagram
  • Defining the Synthetic Population
  • Saving Results (HDF5)
  • Loading Results
• API Reference
  • Core Simulation Interface
  • Physics Engine
  • Data Handling
  • Plotting
  • Composition Models

Installation

Install the latest stable release from PyPI:

pip install pa3py

Or clone the repository and install from source:

git clone https://github.com/mmmaxii/PA3Py.git
cd PA3Py
pip install .

Requirements

• Python ≥ 3.9

• TripodPy simulation output (HDF5 snapshots)

• numpy, scipy, h5py, matplotlib