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HeloiseS / hoki

Bridging the gap between observation and theory
https://heloises.github.io/hoki/intro.html
BSD 3-Clause "New" or "Revised" License
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[BPASS] hmg files and naming convention #66

Closed RyotaInagaki1 closed 4 years ago

RyotaInagaki1 commented 4 years ago

Are all QHE-binary BPASS evolution models in the subdirectories of NEWSINMODS that are named in the format of hmg? Also, to be extra sure, should I look at the Age=0.0 years value of the M2 value of the evolution model to find the initial secondary star mass of the hmg models?

HeloiseS commented 4 years ago

hi!

Sorry what do you mean by hmg format?

RyotaInagaki1 commented 4 years ago

I meant files in the NEWSINMODS directory that are in metallicity subdirectories with suffix hmg (e.g. files in directories such as /bpass-v2.2-newmodels/NEWSINMODS/z001hmg from the BPASS v2.2.1 data package.).

HeloiseS commented 4 years ago

yes - the QHE models are in NEWSINMOD, remember that when BPASS simulates binary evolution not all stars are binaries, it also contains single stars :)

RyotaInagaki1 commented 4 years ago

So are all QHE binary models single stars or stars that have merged? Or do the QHE models contain a combination of both merged binaries and non-merged binaries?

JanJEldridge commented 4 years ago

The HMG/QHE files are just made by assuming they're fully mixed why hydrogen burning is going on. The are only selected in the BPASS population at metallicitiy mass fraction less than or equal to 0.004, at masses of 20Msun and they are secondaries which accrete more than 5% of their initial mass. Mergers are in the primary models if the modeltypes = 0 and extra mixing is not included for those in the current release.

RyotaInagaki1 commented 4 years ago

I should have worded my question a bit more clearly: are QHE models single star models or does the binary QHE secondary model come with a primary? In other words, when dealing with HMG/QHE models, should I bother to use the values in the binary parameters like M2, log10(R2), log10(T2)? Or should I treat the QHE models as single stars?

JanJEldridge commented 4 years ago

They are effectively treated as single stars. However in the population synthesis for working out GW transient event rates the models are used to work out how a QHE+BH system evolves. As the QHE star only gets smaller during it's evolution if the stars aren't interacting at birth they won't interact afterwards. But as mass-loss in stellar winds affecting the orbit it's an easy calculation to do. But otherwise the stellar models themselves are just single stars.