Stellar Spectroscopy Interactive (132.0K)
Astronomy can be defined as the study of light that reaches us from the heavens. That light carries vast stores of information, if you know how to read it. The spectra of stars give clear, unambiguous clues to their temperatures and atmospheric compositions, among other things. This Interactive shows you how it works: that stars of different temperatures have unique blackbody spectra, and that absorption lines within those spectra disclose the atmospheric elements of the star. Choose the temperature of a star, select some elements for the atmosphere, and the correct spectrum appears.
With spectroscopy, we have the tool that lets us study the temperatures and compostions of stars far beyond the solar system. In these problems, we will see how the message of starlight is decoded and applied to the starry host. Let's apply it to the prominent winter constellation, Orion.
At different temperatures, some elements are more prominent than others, but as you pull the slider, you notice changes. These changes were used about a century ago to come up with the seven spectral types we now use. How did this begin?
It is not just atoms that show up in the spectra, and the presence of molecular lines can be especially important in many ways.
We can extend our studies now into the infrared, to objects even cooler than the M stars. Now many elements have a chance to undergo chemical reactions and form compounds, and they too can be used for temperature indicators.