<p>I was reading <a href="http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1961PASJ...13..450H&amp;data_type=PDF_HIGH&amp;whole_paper=YES&amp;type=PRINTER&amp;filetype=.pdf" rel="noreferrer">Stellar Evolution in Early Phases of Gravitational Contraction</a>, by Chushiro Henyey, where he writes,</p>

<blockquote>
  <p>If $L \propto R^{-\alpha}$ along the path, the age of a star from the time when $R=\infty$ is given by
  $$t=C/(1-\alpha), C=GM^2/RL=10^{7.20}\left(\frac{M}{M_{\odot}}\right)^2\frac{R_{\odot}}{R}\frac{L_{\odot}}{L}\text{ years}$$
  where $R$ and $L$ are the present values.</p>
</blockquote>

<p>This seems to be just for stars on the Hayashi track (and treated here just for Population 1 stars). Is there a similar expression for stars on the Henyey track, or is the same expression valid in both scenarios?</p>

CC BY-SA 3.0
2018-02-21T16:56:28.013Z
@RobJeffries Would you consider revisiting to make it an answer now?
called2voyage
CC BY-SA 3.0
2015-05-24T21:07:31.970Z
I won't make this an answer yet. I doubt there is a straightforward way other than to compare with model tracks. The Henyey phase is very shortlived and when it occurs is exquisitely dependent on the adopted radiative opacities and convection treatment.
ProfRob
<star><stellar-evolution>
How is the age of a star on the Henyey track calculated?
HDE 226868
# How is the age of a star on the Henyey track calculated?

(Asked by: username_0 on 2015-05-24)

I was reading [Stellar Evolution in Early Phases of Gravitational Contraction](http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1961PASJ...13..450H&data_type=PDF_HIGH&whole_paper=YES&type=PRINTER&filetype=.pdf), by Chushiro Henyey, where he writes,

> If $L \propto R^{-\alpha}$ along the path, the age of a star from the time when $R=\infty$ is given by
> $$t=C/(1-\alpha), C=GM^2/RL=10^{7.20}\left(\frac{M}{M\_{\odot}}\right)^2\frac{R\_{\odot}}{R}\frac{L\_{\odot}}{L}\text{ years}$$
> where $R$ and $L$ are the present values.

This seems to be just for stars on the Hayashi track (and treated here just for Population 1 stars). Is there a similar expression for stars on the Henyey track, or is the same expression valid in both scenarios?

**Tags:** star, stellar-evolution
> **Comments:**
> **username_2**: I won't make this an answer yet. I doubt there is a straightforward way other than to compare with model tracks. The Henyey phase is very shortlived and when it occurs is exquisitely dependent on the adopted radiative opacities and convection treatment.  
> **username_1**: @RobJeffries Would you consider revisiting to make it an answer now?  

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## 0 answers

