In examining spectra, astronomers have developed powerful techniques to determine a lot of detail about stars, galaxies and composition of inter stellar space, in spite of their great distances.
- determine chemical composition and temperature,
- distinguish stellar classes from sub-dwarfs all the way to super-giants,
- and thus estimate mass, age and luminosity.
In other modules we can learn more about how these spectra help us to determine distance and radial velocity. With that information we can study multiple star systems, find planets around other stars and even observe the expansion of the Universe.
The great advantage of spectral astronomy is that it does not matter how far away the celestial object is. Astronomers even study the spectra of objects in the outer reaches of the known Universe at distances up to 13 billion light year.
- In the module “Stellar Distance” we further discuss the link between luminosity and distance;
- In the module “Stellar Velocity” we explain how the line spectrum is used to very accurately measure radial velocity in space;
- In the module "Multi-λ Astronomy" we explain how modern astronomy is making very important use of the entire EM-spectrum with different types of instruments.