Data Releases

POSYDON shares the precomputed (down-sampled) MESA simulation grids, together with their post-processed products (interpolators and classifiers), so that you can run population synthesis without having to run MESA yourself. These shared datasets are called data releases.

Data Release 1 (DR1)

DR1 was the first published dataset accompanying POSYDON v1. It contains a fixed grid of binary-system MESA simulations. Precise storage and content details of DR1 are described in the original POSYDON paper, Fragos et al. (2023).

Because the code evolved substantially between v1 and v2, DR1 is not the default data used by current POSYDON versions. The default download is DR2.

Data Release 2 (DR2, default)

DR2 accompanies POSYDON v2 and is the default dataset used by the code. It contains fixed grids of single- and binary-star MESA simulations processed through the POSYDON processing pipeline, together with the trained interpolators and classifiers used for population synthesis.

Metallicities

Unlike DR1, DR2 contains simulations over eight different metallicities:

1e-04_Zsun  1e-03_Zsun  ...  (solar Zsun and above)

so that populations can be constructed over a wide range of star formation environments. Each metallicity is a separate download, which is convenient if you only need a subset (e.g. only the solar-metallicity grid to follow the Getting Started examples).

Storage requirements

The amount of disk space you need depends on the subset you download. The table below gives the canonical figures used throughout these documentation, with a single consistent set of numbers:

What you download	Approximate size
Full DR2 dataset	~ 110 GB
Each DR2 metallicity	~ 12 GB
DR1 dataset	~ 40 GB

The exact footprint also depends on how many run types (HMS-HMS, He-He, and so on; see Grid Types) and metallicities you include.

How to download

The simplest way to obtain the data is with the get-posydon-data command-line tool. For example, to download just the solar-metallicity DR2 data used by the quick-start guides:

get-posydon-data DR2_1Zsun

And to download the full DR2 dataset:

get-posydon-data DR2

See the get-posydon-data reference page (api_reference/get_posydon_data.rst) for the full list of options.