<p>To give some context - I am trying to create a simple program that outputs the stellar properties of a star when given its initial mass and current age.</p>

<p>e.g. </p>

<p><strong>Input</strong></p>

<ul>
<li>Initial Mass = 2e30kg</li>
<li>Age = 4.6 Billion years</li>
</ul>

<p><strong>Output</strong></p>

<ul>
<li>Type = Main Sequence</li>
<li>Class = G2V</li>
<li>Radius = 7e5km</li>
<li>Surface Temp = 5778K</li>
</ul>

<p>or</p>

<p><strong>Input</strong></p>

<ul>
<li>Initial Mass = 2e30kg</li>
<li>Age = 10.2 Billion years</li>
</ul>

<p><strong>Output</strong></p>

<ul>
<li>Type = Red Giant</li>
<li>Class = K4V</li>
<li>Radius = 4e7km</li>
<li>Surface Temp = 4000K</li>
</ul>

<p>My issue is that the equations I have used to calculate these output properties are only applicable to the main sequence so cannot be used for other types such as red giants, super giants, or white dwarfs (e.g. The Mass-Luminosity relationship).</p>

<p>I have not had any luck finding the equivalent equations after many hours of googling so I would really appreciate any help or even a google keyword I can search for to put me on track.</p>

CC BY-SA 4.0
2018-08-12T02:33:46.743Z
Hey, Dannii111111, welcome to Astronomy Stack Exchange! Can you tell us what equations you're currently using for main sequence stars? As an aside, I suspect it may be simpler to use lookup tables of preexisting stellar models if you want exact numbers; otherwise, you'll need to use approximations.
HDE 226868
CC BY-SA 4.0
2018-08-12T06:48:41.327Z
Hi HDE, I am using the equations for radius and luminosity given in http://faculty.buffalostate.edu/sabatojs/courses/GES332/reading/mass_luminosity.pdf which I then use to calculate surface temperature and I use the lifetime equation given in http://hyperphysics.phy-astr.gsu.edu/hbase/Astro/startime.html. However all of the equations are only valid for main sequence.
Danni111111
CC BY-SA 4.0
2018-08-13T13:00:26.110Z
You need to interpolate tables of stellar evolutionary models. The kind of general equations you are requesting do not exist.
ProfRob
<star><stellar-evolution><main-sequence>
Are there simplified M-L, M-R, and lifetime equations for non main sequence stars?
Danni111111
# Are there simplified M-L, M-R, and lifetime equations for non main sequence stars?

(Asked by: username_0 on 2018-08-11)

To give some context - I am trying to create a simple program that outputs the stellar properties of a star when given its initial mass and current age.

e.g.

**Input**

* Initial Mass = 2e30kg
* Age = 4.6 Billion years

**Output**

* Type = Main Sequence
* Class = G2V
* Radius = 7e5km
* Surface Temp = 5778K

or

**Input**

* Initial Mass = 2e30kg
* Age = 10.2 Billion years

**Output**

* Type = Red Giant
* Class = K4V
* Radius = 4e7km
* Surface Temp = 4000K

My issue is that the equations I have used to calculate these output properties are only applicable to the main sequence so cannot be used for other types such as red giants, super giants, or white dwarfs (e.g. The Mass-Luminosity relationship).

I have not had any luck finding the equivalent equations after many hours of googling so I would really appreciate any help or even a google keyword I can search for to put me on track.

**Tags:** star, stellar-evolution, main-sequence

> **Comments:**
> **username_1**: Hey, Dannii111111, welcome to Astronomy Stack Exchange! Can you tell us what equations you're currently using for main sequence stars? As an aside, I suspect it may be simpler to use lookup tables of preexisting stellar models if you want exact numbers; otherwise, you'll need to use approximations.  
> **username_0**: Hi HDE, I am using the equations for radius and luminosity given in http://faculty.buffalostate.edu/sabatojs/courses/GES332/reading/mass_luminosity.pdf which I then use to calculate surface temperature and I use the lifetime equation given in http://hyperphysics.phy-astr.gsu.edu/hbase/Astro/startime.html. However all of the equations are only valid for main sequence.  
> **username_2**: You need to interpolate tables of stellar evolutionary models. The kind of general equations you are requesting do not exist.  

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