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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] HR diagrams - unresolved or resolved binaries? #47

Closed sunnc closed 4 years ago

sunnc commented 4 years ago

Hi, I see with HOKI one can plot HR diagrams of single or binary stellar populations. How are the binaries treated in the HR diagrams? Is a binary system considered as an unresolved object on the diagram or as two stars that can be located in different parts of the diagram?

I guess it's the latter since the HR diagrams use parameters of logTe or logG, which can only be defined for individual stars, not for unresolved binaries. However, unresolved binaries seem to be more common in astronomy. So I'm confused.

Thank you!

HeloiseS commented 4 years ago

Thanks for your patience!! Here is Jan Eldridge's answer :)

Each star in a binary are treated at separate points on the diagram. In the instrument paper we do plot eclipsing binaries on the page like this. Although this is "okay" as in the cases where you can't tell if there is a companion or not the secondary will be in a completely different part of the HR diagram.

However the CMDs are different here we do plot stars/binaries as a single object as they're done from your code. Although the treatment of secondaries here might be a bit problematic but it's something we're dealing with in future.