In order to determine what spiral galaxies are composed of, we have to find their mass and their luminosity to produce a mass/luminosity ratio. This will help us determine what spiral galaxies are composed of because we can compare their mass/luminosity ratios to known stellar mass/luminosity ratios. By comparing these two different mass/luminosity ratios, we can determine if galaxies are composed mostly of stellar material. In this report, I will be analyzing 26 different spiral galaxies by finding their mass, their luminosity, and their mass/luminosity ratio. By using these techniques, I will show that only \(10\%\) of the total galactic mass is made of stellar material and that \(90\%\) of a galaxy is composed of non luminous “dark matter.”
A very important question in astronomy is if spiral galaxies are composed entirely of stellar material - stars. This question has puzzled astronomers for years and in this report, I will explain how to find the answer to this question. I will be finding the mass and luminosity of 26 different galaxies in order to find their mass/luminosity ratio. I will be using the Inital Mass Function to find the mass/luminosity ratio of stars and I will compare the two mass/luminosity values in order to find the percent of stellar mass in a galaxy. I will be using data from an astronomy Java program for the galaxy data and Guy Worthey’s Interpolation Medel (an Initial Mass Function program) for the stellar data.