<p>How can I calculate how long a star of a given mass will spend on an evolutionary branch before evolving off it?</p>
<p>I'm thinking about the evolution of low mass stars from the subgiant branch to the red giant branch and beyond. I know of timescales such as dynamic and nuclear etc, and I want to learn how I can calculate how long a star of a given mass will spend on a branch before evolving off it.</p>
<p>I've tried using the nuclear timescale equation, but this relies on having Hydrogen in the core, and evolved stars may not have any H in the core.</p>
<p>I've seen on the internet I'm aiming for a value between 1000 and 1 billion years, but don't know how to work this out.</p>
<p>Thanks for your help.</p>
<p>I also posted here:
<a href="https://physics.stackexchange.com/questions/737825/how-can-i-calculate-evolutionary-timescales-of-low-mass-stars">https://physics.stackexchange.com/questions/737825/how-can-i-calculate-evolutionary-timescales-of-low-mass-stars</a></p>

CC BY-SA 4.0
2022-11-23T22:53:32.373Z
Just a note to say that if you cross post a question to more than one SE it's advisable to (at least) edit each question to include links to the other copies.  This helps people avoid duplication of effort.  In general cross posting is somewhat discouraged but not completely against the rules.
StephenG - Help Ukraine
CC BY-SA 4.0
2022-11-24T23:38:59.780Z
Ok thanks Stephen. That does sound reasonable
Holly Bee
<star><stellar-evolution><red-giant>
How can I calculate evolutionary timescales of low mass stars?
Holly Bee
# How can I calculate evolutionary timescales of low mass stars?

(Asked by: username_0 on 2022-11-23)

How can I calculate how long a star of a given mass will spend on an evolutionary branch before evolving off it?

I'm thinking about the evolution of low mass stars from the subgiant branch to the red giant branch and beyond. I know of timescales such as dynamic and nuclear etc, and I want to learn how I can calculate how long a star of a given mass will spend on a branch before evolving off it.

I've tried using the nuclear timescale equation, but this relies on having Hydrogen in the core, and evolved stars may not have any H in the core.

I've seen on the internet I'm aiming for a value between 1000 and 1 billion years, but don't know how to work this out.

Thanks for your help.

I also posted here:
<https://physics.stackexchange.com/questions/737825/how-can-i-calculate-evolutionary-timescales-of-low-mass-stars>

**Tags:** star, stellar-evolution, red-giant
> **Comments:**
> **username_1**: Just a note to say that if you cross post a question to more than one SE it's advisable to (at least) edit each question to include links to the other copies.  This helps people avoid duplication of effort.  In general cross posting is somewhat discouraged but not completely against the rules.  
> **username_0**: Ok thanks Stephen. That does sound reasonable  

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