The Classification of Variable Stars Based on Photometry and Spectroscopy Casey McNamara

Abstract Variable stars are vital to us because they allow us to discover other important facts about our solar system, as well as providing new information every day about themselves. In fact, Harlow Shapely discovered in the 1920’s that the sun is not at the center of our universe by using variable stars. Some variable stars are so large that we can detect them in some of the nearby galaxies; they also provide the major method we have of measuring distances to these galaxies. You can classify variable stars by their spectral type, luminosity class, and chemical composition. Today we classify them into eruptive variables, pulsating variables, rotating variables, cataclysmic variables and eclipsing variables. There are also more specific types such as Cephieds, RR Lyrae variables, Mira type variables, and RV Tari variable stars. I am going to be classifying variable stars in to these categories using information I have gathered on their period length, magnitudes, and spectroscopy.

Need Variable stars let us know more about the enviornment around them, so we know more about the universe itself Variable stars are constantly changing and evolving so it is important to have frequent analyzation and classification

Knowledge Base An example of a light curve of a variable star

Hypothesis Null Hypothesis: All variable stars will fall into the categories of intrinsic or extrinsic, and they will be classified based on spectroscopic and photometric information. Alternate Hypothesis: I will not be able to classify my stars into any groups.