What+tools+do+you+need+to+study+AGN?+Spectroscopy

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 * Spectroscopy:

__What is it?__** - **Spectroscopy** pertains to the dispersion of an object's light into its component colors (i.e. energies).
 * [[image:http://upload.wikimedia.org/wikipedia/commons/f/f5/Light_dispersion_conceptual_waves.gif caption="http://upload.wikimedia.org/wikipedia/commons/f/f5/Light_dispersion_conceptual_waves.gif" link="http://upload.wikimedia.org/wikipedia/commons/f/f5/Light_dispersion_conceptual_waves.gif"]] ||
 * http://upload.wikimedia.org/wikipedia/commons/f/f5/Light_dispersion_conceptual_waves.gif ||

By performing this dissection and analysis of an object's light, astronomers can infer the physical properties of that object (such as temperature, mass, luminosity and composition). [|Source]

There are three types of spectra: Continuous, Emission, and absorption lines.**
 * __Types:__

**Continuous** is all wavelengths of light produced by hot, dense objects. EX: the sun is hot and dense, it produces the light to us which is the visible spectrum.

EX: hydrogen gas, when electricity runs through it, gives off a couple of spectra. I think this could also be like neon lights that are filled with argon and other noble gases (most likely).
 * Emission** line is a short wavelength produced by hot, low-density objects.
 * [[image:Emission_lines.jpg width="488" height="194" caption="Emission_lines.jpg"]] ||
 * Emission_lines.jpg ||

EX: any gas
 * Absorption** line is a wavelength absorbed by cool gas/gases (the light comes from a different source). It absorbs what ever wavelength it would usually emit at high temperatures.
 * [[image:Absorption_Lines.jpg width="477" height="185" caption="Absorption_Lines.jpg"]] ||
 * Absorption_Lines.jpg ||

These spectra lines (emission and absorptions) are caused by ionized atoms. The atoms become ionized when electrons are stripped away from the atom. Hotter = more ionized. Source (see Original page) Other sources: [|http://loke.as.arizona.edu/~ckulesa/camp/spectroscopy_intro.html] KH

__**Graphs:**__ This graph represents the spectra of different stars from O (hottest/youngest) to M (coldest/oldest).
 * [[image:http://www.jb.man.ac.uk/distance/life/sample/stars/spectra.gif width="332" height="482" caption="http://www.jb.man.ac.uk/distance/life/sample/stars/spectra.gif"]] ||
 * http://www.jb.man.ac.uk/distance/life/sample/stars/spectra.gif ||


 * [[image:O_M_characteristics.jpg caption="From Message of Starlight"]] ||
 * From Message of Starlight ||