Variable StarsVariable stars are simply stars that vary in brightness. There are two kinds of variable stars, intrinsic, and extrinsic. Variable stars are further classified as either intrinsic pulsating and cataclysmic (eruptive) variables and extrinsic eclipsing binary and rotating variables. More information on variable star types is available from the AAVSO Types of Variable Stars page. This is an area that amateurs can provide valuable information to professional astronomers. Professional astronomers do not have the telescope time to do long term observing of variable stars. This is where the amateur comes in. Amateurs have provided volumes of data to the astronomical community on unusual stellar events. This has helped coordinate the scheduling of professional observing programs, coordinate visual spectrum observations with other professional astronomical sensor data and more.
Variable star observing can be as easy or intricate as you would like it to be. It can be done in light polluted or dark skies. The easiest way to observe is with the unaided eye. Other methods of observing include the use of binoculars, telescopes of all types, CCD cameras and even special sensors if desired. The skill of locating the same star and estimating its brightness as compared to others are well documented in the references listed below. The time frame for taking data can take hours or up to years depending on the star or observing program in question. The frequency of observations for a given star range from weekly, to every clear night and even to every 10 minutes depending on the type of variable star it is. Various organizations have forms to fill out on how to take and submit data. These organizations are also listed below. Some of these organizations have special interest groups such as CCD, photoelectric photometry, eclipsing binary stars, visual, sunspot, sudden ionosphere disturbance, nova search, super nova search and RR Lyra observing programs. The American Association of Variable Star Observers (AAVSO) even has a "Hands on Astrophysics" educational program funded by the National Science Foundation. This allows students to learn the scientific process and develops skills in science, math, computing and other areas.
For more information contact:
WCAC-VSO - The Wilderness Center Astronomy Club special interest group on variable star observing.
Sky and Telescope Variable Star page - A good place to start.
American Association of Variable Star Observers (AAVSO)- Large amounts of information.
Telescope Simulator - From the AAVSO. A dynamic presentation that illustrates how to estimate the magnitude of a variable star and introduces you to the AAVSO. Takes about 15 minutes to go through it.
Center for Backyard Astrophysics - Long term photometric studies of cataclysmic variables.
Astronomical Society of Australia Variable Star Group - Variable star FAQ.
British Astronomical Association Variable Star Section (BAAVSS) - Lots of data on line.
Variable Star International Network (VSNET)- Email list.
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Last updated January 11, 2009, by Brian Gray