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BPASS v2.2

Latest BPASS version 2.2.1 Data Release (July 2018)

This version of BPASS represents an extension and modification of our v2.1 and older models.

The more important new features and results included in this release of BPASS include: calculation of a significantly larger number of stellar models, release of a wider variety of predictions of stellar populations including Lick indices, inclusion of new stellar atmosphere models, improvements in the treatment of low mass stars, and modified binary parameter distributions. These result in significantly better handling of old stellar populations

BPASS v2.1 was fully described in a peer-reviewed paper: Eldridge, Stanway et al, 2017, PASA 34 58, arXiv:1710.02154. This data release, v2.2, builds on the detailed modelling described in that paper, but includes improved or modified prescriptions in some areas. These are described and results presented in Stanway & Eldridge (2018, MNRAS in press). The version v2.2.1 subrelease represents a minor iteration. The differences are very slight for most applications and resulted from fixing a bug that affected scaling of a handful of hot, young white dwarf atmospheres. This led to negative fluxes in absorption lines at a handful of ages and wavelengths.

We have also produced an updated User Manual which we strongly recommend users examine. This is available typeset in both Arial and OpenDyslexic (a font designed for use by those with specific learning differences).

The v2.2.1 data release is routinely stored on Google Drive at

The slightly older v2.2 models are still online at - the changes are very slight for virtually all applications.

We caution that the full data release is very large (particularly if individual stellar models are downloaded). Filenames have now been updated to incorporate IMF names as described in the user manual. The release contains data products as follows:

1. Stellar Model Outputs:

  • v2.2 Binary stellar models with photometric colours
  • v2.2 New OB stars atmosphere models (unchanged from v2.1)

2. Stellar Population Outputs (all versus age):

  • Massive star type number counts
  • Core collapse supernova rates
  • Yields, energy output from winds and supernovae and ejected yields of X , Y and Z
  • Stellar population mass remaining
  • HR diagram (isochronal contours)

3. Spectral Synthesis Outputs (all versus age):

  • Spectral Energy Distributions
  • Ionizing flux predictions
  • Broadband colours
  • Lick Indices
  • Mass to Light Ratios
  • Colour-Magnitude Diagram (CMD) making code

For full details, and README details for the data files, we again recommend the User Manual.

We would appreciate the inclusion of the following acknowledgement where appropriate:

“This work made use of v2.2.1 of the Binary Population and Spectral Synthesis (BPASS) models as described in Eldridge, Stanway et al. (2017) and Stanway & Eldridge et al. (2018).”

For the Xiao, Stanway & Eldridge (2018) nebular gas emission models (based on BPASS v2.1) please see our v2.1 nebular emission sub page.