<p>I have asked this on Physics Stack Exchange but Astronomy is probably more appropriate. I have been given the task of synthesising an elliptical galaxy, a starburst galaxy and a spiral galaxy (considering the arms and the bulge separately and adding them) using stellar spectra which I have classified. I need to add different weightings of five types of stars to produce a normalised spectrum of each of these galaxies. I have spectra for giants, main sequence stars and sub-giants with varying stellar types (O, B, A, F, G, K, M). I know that Spiral arms and the starburst are going to be primarily young stars, while the spiral bulge and the elliptical will be of older stars, but I have no idea which types or luminosity classes of stars I would use and their weightings in each. Can anyone offer any information or resources where I would find good information on adding different types of star to 'create' a galaxy?</p>

CC BY-SA 3.0
2014-11-03T01:28:03.413Z
Don't you have any additional data on this task? Are you aware of the `mass function`?
Py-ser
CC BY-SA 3.0
2014-11-03T02:14:13.520Z
No I am not aware of the mass function and have no additional data. I think it is intended to be done in a qualitative manner but require specific spectra.
ginny
CC BY-SA 3.0
2014-11-03T02:35:33.787Z
I see. Please, could you specify what you mean by `sinthesizing`? I was probably on another wave of thought.
Py-ser
CC BY-SA 3.0
2014-11-03T04:38:33.053Z
Well my interpretation is that I have various stellar spectra, and I need to combine certain appropriate ones (depending on the galaxy type) with different weightings to acquire a spectrum for the galaxy if that makes sense?
ginny
CC BY-SA 3.0
2014-11-03T06:21:22.537Z
It is important to understand if you need to synthesize the spectrum or the population. Try to take a look at [here](http://cosmology.lbl.gov/talks/Conroy_09.pdf)
Py-ser
CC BY-SA 3.0
2014-11-05T17:25:38.777Z
For the simple kind of synthesis you want to do, you probably want to have a look on [Faber (1972)](http://adsabs.harvard.edu/abs/1972A%26A....20..361F) paper. For more complicated stuff (with a proper Initial Mass Function and a Star Formation History), you will definitely want to have a look on the [Bruzual & Charlot (2003)](http://adsabs.harvard.edu/abs/2003MNRAS.344.1000B) paper.
MBR
<galaxy><star-systems><classification>
Synthesising types of galaxies using various stellar spectra
ginny
# Synthesising types of galaxies using various stellar spectra

(Asked by: username_0 on 2014-11-02)

I have asked this on Physics Stack Exchange but Astronomy is probably more appropriate. I have been given the task of synthesising an elliptical galaxy, a starburst galaxy and a spiral galaxy (considering the arms and the bulge separately and adding them) using stellar spectra which I have classified. I need to add different weightings of five types of stars to produce a normalised spectrum of each of these galaxies. I have spectra for giants, main sequence stars and sub-giants with varying stellar types (O, B, A, F, G, K, M). I know that Spiral arms and the starburst are going to be primarily young stars, while the spiral bulge and the elliptical will be of older stars, but I have no idea which types or luminosity classes of stars I would use and their weightings in each. Can anyone offer any information or resources where I would find good information on adding different types of star to 'create' a galaxy?

**Tags:** galaxy, star-systems, classification
> **Comments:**
> **username_1**: Don't you have any additional data on this task? Are you aware of the `mass function`?  
> **username_0**: No I am not aware of the mass function and have no additional data. I think it is intended to be done in a qualitative manner but require specific spectra.  
> **username_1**: I see. Please, could you specify what you mean by `sinthesizing`? I was probably on another wave of thought.  
> **username_0**: Well my interpretation is that I have various stellar spectra, and I need to combine certain appropriate ones (depending on the galaxy type) with different weightings to acquire a spectrum for the galaxy if that makes sense?  
> **username_1**: It is important to understand if you need to synthesize the spectrum or the population. Try to take a look at [here](http://cosmology.lbl.gov/talks/Conroy_09.pdf)  
> **username_2**: For the simple kind of synthesis you want to do, you probably want to have a look on [Faber (1972)](http://adsabs.harvard.edu/abs/1972A%26A....20..361F) paper. For more complicated stuff (with a proper Initial Mass Function and a Star Formation History), you will definitely want to have a look on the [Bruzual & Charlot (2003)](http://adsabs.harvard.edu/abs/2003MNRAS.344.1000B) paper.  

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## 0 answers

