In: Physics
is it possible to identify different types of quasars based on its color? please provide a refrence so i can read into it more
Quasars are extremely luminous and were first identified as being high redshift sources ofelectromagnetic energy, including radio waves and visible light, that appeared to be similar to stars, rather than extended sources similar to galaxies. Their spectra contain very broad emission lines, unlike any known from stars, hence the name "quasi-stellar". Their luminosity can be 100 times greater than that of the Milky Way.
Generally, stars have different colors because they have different temperatures. However, stars are not perfect thermal sources. For instance, a certain type of star called a carbon star has a very red color. Carbon in the star's atmosphere absorbs much of its blue light, making the cool star appear even redder than it should for its temperature.
A star's color can usually give you a good idea of its temperature, but it is always a good idea to double-check by measuring the star's spectrum with a spectrograph. In fact, whenever the SDSS sees an extremely red star, software automatically targets the star for follow-up measurements with the spectrograph.
Astronomers use colors to classify many objects including stars, galaxies and quasars. They can use colors to estimate the spectral types of stars, the types of galaxies, to sort asteroids into different classes, and to estimate the distances to galaxies and quasars.