Have questions not answered here? CONTACT US: j.eldridge [at] auckland.ac.nz and e.r.stanway [at] warwick.ac.uk 

The Binary Population and Spectral Synthesis code (BPASS) is the result of combining my stellar evolution models with libraries of synthetic atmosphere spectra to create a unique tool to model many details of stellar populations. While similar codes (such as starburst99) exist BPASS has important features, each of which set it apart from other codes and in combination make it the cutting edge. First, and most important, is the inclusion of binary evolution in modelling the stellar populations. The general effect of binaries is to cause a population of stars to look bluer at an older age than predicted by single-star models. Secondly, detailed stellar evolution models are used rather than an approximate rapid population synthesis method. Thirdly, only theoretical model spectra are used in the syntheses with as few empirical inputs as possible to create completely synthetic models to compare with observations.  

On this site we make available standard outputs from our code for single and binary star populations. Select the data you require from the menu above. If you require data that is not here please email us.

The current version of the code is Version 2.2.1 (July 2018). 

The v2.2 release (May 2018) was accompanied by a release paper: Stanway & Eldridge (2018), which builds on the more detailed model description in Eldridge, Stanway et al (2017, PASA), arXiv:1710.02154.  Subversion v2.2.1 fixes a slight mis-scaling of a small number of white dwarf atmospheres, which resulted in negative fluxes at a handful of ages and wavelengths. Changes to most observable parameters are very small. 

 

Older releases:

Version 2.1

• Eldridge, Stanway, Xiao, McClelland, Taylor, Ng, Greis & Bray, 2017, PASA in press. Binary Population and Spectral Synthesis Version 2.1: construction, observational verification and new results

Version 2.0: this was the first release with many improvements to BPASS, it is discussed in:

• Eldridge & Stanway, 2016, MNRAS, 432, 3302, BPASS predictions for Binary Black-Hole Mergers
• Stanway, Eldridge & Becker, 2016, MNRAS, 456, 485. Stellar population effects on the inferred photon density at reionization.

Version 1.1: this was the version that first included stars that experience quasi-homogeneous evolution at the lowest metallicities of Z=0.001 and 0.004. The version and results are outlined in:

• Eldridge & Stanway, 2012, MNRAS, 419, 479. The effect of stellar evolution uncertainties on the rest-frame ultraviolet stellar lines of C IV and He II in high-redshift Lyman-break galaxies.
• Eldridge, Langer & Tout, 2011, MNRAS, 414, 3501. Runaway stars as progenitors of supernovae and gamma-ray bursts.

Version 1.0: this was the first version of the code. The models and synthesis code are outlined in the following papers:

• Eldridge & Stanway, 2009, MNRAS, 400, 1019. Spectral population synthesis including massive binaries.
• Eldridge, Izzard & Tout, 2008, MNRAS, 384, 1109. The effect of massive binaries on stellar populations and supernova progenitors.

 

BPASS results: outlining the predictions from BPASS and the importance of interacting binaries on stellar populations are outlined in:

Version 2:

• Eldridge, Stanway & Tang, 2018, MNRAS in press A consistent estimate for Gravitational Wave and Electromagnetic transient rates [Data here]
• Xiao, Galbany, Eldridge & Stanway, 2018, MNRAS in press Core-collapse supernovae ages and metallicities from emission-line diagnostics of nearby stellar populations
• Bray & Eldridge, 2018, MNRAS, 480, 5657 Neutron star kicks - II. Revision and further testing of the conservation of momentum `kick' model
• Xiao, Stanway & Eldridge, 2018, MNRAS, 477,904 Emission-line diagnostics of nearby H II regions including interacting binary populations
• Greis et al, 2017, MNRAS, 470, 489. Radio observations confirm young stellar populations in local analogues to z~5 Lyman break galaxies
• Moriya & Eldridge, 2016, MNRAS, 461, 2155. Rapidly evolving faint transients from stripped-envelope electron-capture supernovae
• Bray & Eldridge, 2016, MNRAS 461, 3747. Neutron Star Kicks and their Relationship to Supernovae Ejecta Mass
• Eldridge & Maund, 2016, MNRAS, 461L, 117. The disappearance of the helium-giant progenitors of the type Ib supernova iPTF13bvn and constraints on its companion.
• Wofford, Charlot, Bruzual, Eldridge, Calzetti et al., MNRAS 457, 4296. A Comphrehensive Comparitive test of seven widely-used spectral synthesis models against multi-band photometry of young massive clusers.

Version 1:

• Xiao & Eldridge, 2015, MNRAS, 452, 2597. Core-collapse supernova rate synthesis within 11 Mpc
• Stanway et al, 2014, MNRAS, 444, 3466. Interpreting high [O III]/H β ratios with maturing starbursts
• Eldridge, 2012, MNRAS, 422, 794. Stochasticity, a variable stellar upper-mass limit, binaries and star-formation rate indicators.
• Eldridge & Relaño, 2011, MNRAS, 411, 235. The red supergiants and Wolf-Rayet stars of NGC 604.
• Eldridge, 2009, MNRAS, 400, 20. A new-age determination for γ2 Velorum from binary stellar evolution models.

This site also hosts other results from the Auckland Stars Group that are not included in BPASS. These can be found under the Other Results page. To date these numbers can be found at:

• McClelland & Eldridge (2016), MNRAS, 459, 1505.  

Current members of the BPASS team:

• JJ Eldridge: j.eldridge [at] auckland.ac.nz
• Elizabeth Stanway: e.r.stanway [at] warwick.ac.uk.
• Lin Xiao
• Liam McClelland
• John Bray

BPASS collaborators:

• Stephanie Greis
• Aida Wofford
• Monica Relaño
• Joe Walmswell
• Maciej Hermanowicz

The creation of BPASS has been supported by:

 

 

 

• Department of Physics, University of Auckland, New Zealand.
• Department of Physics, University of Warwick, United Kingom.
• Astrophysics Research Centre, Department of Physics, Queen’s University Belfast, Northern Ireland.
• Institute of Astronomy, University of Cambridge, United Kingdom.
• Institut d’Astrophysique de Paris, University de Pierre & Marie Curie, France.