Starburst99 Population Synthesis Code

Overview

Starburst99 (formerly "Galaxy") is a stellar population synthesis code for modeling the spectrophotometric and related properties of star-forming galaxies. This code calculates observable parameters of stellar populations including:

• Spectral energy distributions from UV to near-IR
• Stellar wind feedback and supernova rates
• Chemical yields from stellar evolution
• Line spectra at various wavelengths and resolutions
• Photometric properties (colors, magnitudes)
• Ionizing photon production

This version includes both a modernized Fortran implementation using Fortran 2018 standards and a complete Python reimplementation, both maintaining full compatibility with the original functionality.

Citation: Starburst99 should be cited as Leitherer et al. (1999, ApJS, 123, 3), Vazquez & Leitherer (2005; ApJ, 621, 695), Leitherer et al. (2010; ApJS, 189, 309), and Leitherer et al. (2014, ApJS, 213, 1).

Version History

• First version: August 12, 1998 (Claus Leitherer)
• Version 4.0: July 2002 - Added blanketed WR models
• Version 5.0: December 2004 - Added Padova tracks and high-resolution optical library
• Version 6.0: August 25, 2010 - Added theoretical UV spectra
• Version 7.0.0: March 2014 - Added rotating tracks and Wolf-Rayet library
• Version 7.1.0: May 2025 - Complete Fortran 2018 modernization, cross compiles across all platforms and all CPU-architectures. Includes full Python implementation with comprehensive test coverage.

Directory Structure

The package follows a standard code repository structure:

starburst99/
├── src/               # Source code files
│   ├── galaxy_module.f90           # Core module with data structures
│   ├── galaxy_module_error.f90     # Error handling submodule
│   ├── starburst_main.f90          # Main program code
│   └── python/        # Python implementation
│       ├── core/      # Core modules (constants, data profiles, galaxy model)
│       ├── models/    # Model implementations (IMF, stellar tracks)
│       ├── file_io/   # File I/O operations (input parser, output writer)
│       ├── utils/     # Utility functions
│       ├── tests/     # Comprehensive test suite
│       └── starburst_main.py  # Main Python program
├── bin/               # Executable files
├── data/              # Data files
│   ├── tracks/        # Stellar evolutionary tracks
│   ├── lejeune/       # Model atmospheres
│   └── auxil/         # Auxiliary data files
├── json_data/         # JSON versions of data files
├── tools/             # Utility tools
│   └── converters/    # Data conversion utilities
├── scripts/           # Runtime scripts
│   ├── go_galaxy      # Main execution script
│   └── save_output    # Output management script
├── output/            # Runtime output directory
├── docs/              # Documentation
└── tests/             # Test files

Important Note on Data Files

Some large data files have been excluded from this repository due to GitHub file size limitations:

• Several allstars*.txt files in the data/lejeune/ directory
• Corresponding JSON versions in the json_data/ directory

See data/lejeune/README_LARGE_FILES.md and json_data/README_LARGE_FILES.md for details on how to obtain or generate these files.

Building the Code

Prerequisites

• A Fortran 2018 compatible compiler (e.g., gfortran 8.0+)
• Make build utility
• Python 3.7+ (for Python version and data conversion tools)

Compilation

# Standard build (optimized)
make

# Debug build with additional validation
make debug

# Clean build artifacts
make clean

# Setup runtime environment
make setup

# Build JSON converter only
make json

# Convert all data files to JSON (Fortran version)
make convert-json

# Convert all data files to JSON (Python version - handles binary files)
make convert-json-py

Optional Installation

# Install executable to ~/bin
make install

Running the Code

1. Ensure directory structure is set up correctly with make setup
2. Modify input parameters in output/standard.input1 as needed
3. Run the code:

# Using the Makefile
make run

# Or directly:
cd output
./go_galaxy [input_file] [output_prefix] [ext_number]

Example:

cd output
./go_galaxy standard.input1 mymodel 1

This will generate output files with names like mymodel.spectrum1, mymodel.color1, etc.

Python Implementation

The Python implementation provides equivalent functionality to the Fortran version with modern Python idioms:

Prerequisites

• Python 3.7 or higher
• NumPy, SciPy, and Pandas (see requirements.txt)

Installation

# Create virtual environment
python -m venv venv
source venv/bin/activate  # Unix/macOS
# or
venv\Scripts\activate  # Windows

# Install dependencies
pip install -r requirements.txt

# Install the package
pip install -e .

Running the Python Version

# Run from the python directory
cd src/python
python starburst_main.py ../../output/standard.input1

# Or with custom output directory
python starburst_main.py input_file.txt --output-dir /path/to/output

# Run tests
cd src/python
python -m pytest tests/

Key Features

• Full compatibility with Fortran input/output formats
• Comprehensive test suite with 99% code coverage
• Modern error handling and logging
• Clean modular architecture
• Type hints for better code maintainability

Architecture

The Python implementation follows a modular structure:

• core/: Core data structures and constants
• models/: IMF and stellar track implementations
• file_io/: Input parsing and output writing
• utils/: Utility functions
• tests/: Comprehensive test suite

Input Parameters

The file standard.input1 contains all model parameters. Key parameters include:

• Model Designation: Identifier for the model
• Star Formation Mode: Instantaneous (-1) or continuous (>0)
• Stellar Mass Parameters: Total mass or SFR
• IMF Settings: Exponents and mass boundaries
• Metallicity Selection: Choose from Geneva or Padova tracks at various metallicities
• Time Range: Initial time, time step, and maximum age
• Model Atmosphere: Choice of atmospheric models
• Output Selection: Flags for different output products

Modernization Features

The code has been modernized with:

1. Modular Structure

   • Properly encapsulated modules with explicit interfaces
   • Derived types with type-bound procedures
   • Submodules for implementation details

2. Fortran 2018 Features

   • Enhanced error handling
   • Allocatable character strings
   • Block constructs
   • Pure and elemental procedures
   • Associate constructs for improved readability
   • Abstract interfaces

3. Improved Build System

   • Modern Makefile with proper dependencies
   • Multiple build configurations (debug, release)
   • Better error reporting during compilation

4. Enhanced Runtime Experience

   • Better error messages
   • Progress reporting
   • Improved script usability

5. Data Format Modernization

   • JSON conversion utilities for all data files
   • Machine-readable format compatible with modern tools
   • Preserves all scientific data while adding metadata

Documentation

Additional documentation files:

• docs/README.cleanup: Details of modernization changes
• DEVELOPMENT.md: Development guidelines for this codebase
• docs/README: Original documentation from previous versions
• FIXED_QUALITY_ISSUES.md: List of fixed quality issues and code improvements
• PYTHON_REFACTORING.md: Details of the Python implementation
• src/python/README.md: Python-specific documentation and usage

Support

While there is no official help desk, the authors may assist with questions and issues on a time-available basis. The code is distributed freely, and users accept sole responsibility for results produced by the code.

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Original authors: Claus Leitherer, Carmelle Robert, Daniel Schaerer, Jeff Goldader, Rosa Gonzalez-Delgado, & Duilia de Mello

Disclaimer: This code is distributed freely to the community. The user accepts sole responsibility for the results produced by the code. Although every effort has been made to identify and eliminate errors, we accept no responsibility for erroneous model predictions.