VULCAN

Photochemical and thermochemical kinetics for (exo)planetary atmospheres; a fast, open-source 1D chemical kinetics code. This distribution of VULCAN contains a number of performance and usability improvements, and is integrated into the PROTEUS framework.

Full documentation: proteus-framework.org/VULCAN. When contributing to this repository, please consult the contributing guide.

Theory papers:

• Tsai et al. 2021 (with photochemistry)
• Tsai et al. 2017 (without photochemistry)

Quick start

pip install -U -e .
cd fastchem_vulcan && make && cd ..
python run_vulcan.py

This installs VULCAN, compiles FastChem (used for equilibrium initialization), and runs the default model (the hot Jupiter HD 189733b) with live plotting. It takes a few minutes; results are written to output/ as NetCDF, Pickle, and Plain Text files.

Settings for running VULCAN via the terminal are defined by src/vulcan/config.py.

For example, weaker vertical mixing:

self.Kzz_prof  = 'const'
self.const_Kzz = 1.e7   # cm^2/s

or a carbon-rich (C/O = 1) atmosphere:

self.use_solar = False
self.O_H = 5.37e-4
self.C_H = 5.37e-4

Pass -n to skip regenerating the chemistry from the network (only valid if you haven't edited it).

Plotting results

cd tools/
python plot_vulcan.py <output.pkl> <species> <plot_name> [-h]

Reads a pickled output (e.g. output/example.pkl, written when save_type includes 'pickle') and plots mixing-ratio profiles for the given comma-separated species (no spaces). Plots against pressure by default, or height with -h.