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?

  • $\begingroup$ Don't you have any additional data on this task? Are you aware of the mass function? $\endgroup$
    – Py-ser
    Nov 3, 2014 at 1:28
  • $\begingroup$ 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. $\endgroup$
    – ginny
    Nov 3, 2014 at 2:14
  • $\begingroup$ I see. Please, could you specify what you mean by sinthesizing? I was probably on another wave of thought. $\endgroup$
    – Py-ser
    Nov 3, 2014 at 2:35
  • $\begingroup$ 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? $\endgroup$
    – ginny
    Nov 3, 2014 at 4:38
  • $\begingroup$ It is important to understand if you need to synthesize the spectrum or the population. Try to take a look at here $\endgroup$
    – Py-ser
    Nov 3, 2014 at 6:21


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