ASTRA

ASTRA stands for Adaptive STellar Research Architecture.

ASTRA is a modern Julia framework for stellar structure and evolution with a deliberately narrow initial scope: single-star, 1D, spherically symmetric, hydrostatic, forward-solver-first stellar modeling. It is being built as a clean research laboratory for classical structure methods, validation workflows, and later method comparisons such as Entropy-DAE.

Why ASTRA exists

ASTRA has a different job than Stellax.

• Stellax is the flagship differentiable stellar modeling framework, where gradients and inference-native workflows are central.
• ASTRA is the Julia-first forward-model laboratory, where clarity, validation readiness, solver architecture, and controlled method comparison come first.

ASTRA is not a MESA clone, not a feature warehouse, and not a rushed attempt to implement every piece of stellar evolution at once.

Current bootstrap status

This repository bootstrap covers Milestone 0 and the beginning of Milestone 1:

• a root Julia package scaffold,
• a pedagogical MystMD documentation site,
• a modular src/ tree,
• an explicit StellarModel contract with StructureState, CompositionState, and EvolutionState,
• tests and examples for the scaffolded interfaces,
• planning and contributor guidance,
• toy physics and solver pathways that are intentionally honest about being placeholders.

The bootstrap does not claim to provide a research-grade stellar solver yet.

Repository layout

src/        Julia package source
test/       Unit and scaffold checks
docs/       MystMD website and planning artifacts
examples/   Small runnable examples
benchmark/  Benchmark placeholders and future performance notes
scripts/    Local developer scripts

Getting started

Julia is not vendored into the repository. The recommended installation route is juliaup, which the Julia project currently recommends for installing the latest stable Julia release:

https://julialang.org/downloads/

Once Julia is installed:

julia --project=. -e 'using Pkg; Pkg.instantiate(); Pkg.precompile()'
julia --project=. -e 'using ASTRA'
julia --project=. -e 'using Pkg; Pkg.test()'
julia --project=. scripts/run_examples.jl

Docs

ASTRA’s documentation is a MystMD handbook rather than an auto-generated API dump. To preview it locally:

cd docs/website
myst start

To build the static site:

cd docs/website
myst build --site --html --strict

Design rules

• Correctness before performance.
• Validation before feature growth.
• Small public API, rich internal modularity.
• Classical baseline first.
• Entropy-DAE belongs in ASTRA later, but does not define ASTRA’s whole identity.
• cgs Float64 values in the solver path, with units enforced by names, docs, and tests.

License

BSD-3-Clause. See LICENSE.