8B30.40 - Variable Stars - Cepheid Variable Stars

Photo Credit: NASA, HST, W. Freedman (CIW), R. Kennicutt (U. Arizona), J. Mould (ANU)
Photo Credit: NASA, HST, W. Freedman (CIW), R. Kennicutt (U. Arizona), J. Mould (ANU)
Code Number:
Demo Title:
Variable Stars - Cepheid Variable Stars
Area of Study:
Stellar Astronomy
Power Supply, Tap Switch, 6 to 8 Volt Light Bulb, 90,000 mf Capacitors, Vernier Interface and Light Sensor, Computer.

Connect the power supply, light bulb, and tap switch in series, and set the power supply to 4 volts DC.  Place the capacitors in parallel with the light bulb.  When you press the tap switch, the luminosity will increase quickly but when you then release the tap switch the luminosity will decrease much more slowly.  This is a fair representation of actual Cepheid Variable light curves.    

  • Jay M. Pasachoff and Jason W. Mativi, "Demonstrating the Cosmic Distance Ladder with Cepheids", TPT, Vol. 58, #1, Jan. 2020, p. 6.
  • George S. Mumford, "Scatter", TPT, Vol. 32, #3, Mar. 1994, p. 133.
  • John R. Percy, "Variable Stars", TPT, Vol. 31, #9, Dec. 1993, p. 541.
  • David L. DuPuy, "Using a Classroom Variable Star in Introductory Astronomy Courses", AJP, Vol. 54, #11, Nov. 1986, p. 976.
  • J. B. Rafert and R. C. Nicklin, "Observing Variable Stars Indoors with a Microcomputer and Phototransistor", AJP, Vol. 51, #7, July 1983, p. 668.
  • Terry R. Flesch, "Observing Simulated Cepheid Variable Stars in an Introductory Astronomy Lab", AJP, Vol. 47, #3, March 1979, p. 232.
  • Steven K. Blau, "A Standard Candle Slowly Burns Down", Physics Today, Vol. 64, #3, Mar. 2011, p. 22.
  • Dorota M. Skowron, Jan Skowron, Przemek Mróz, Andrzej Udalski, Paweł Pietrukowicz, Igor Soszyński, Michał K. Szymański, Radosław Poleski, Szymon Kozłowski, Krzysztof Ulaczyk, Krzysztof Rybicki, and Patryk Iwanek, "A Three-Dimensional Map of the Milky Way using Classical Cepheid Variable Stars", Science, Vol. 365, #6452, Aug. 2019, p. 478.

Disclaimer: These demonstrations are provided only for illustrative use by persons affiliated with The University of Iowa and only under the direction of a trained instructor or physicist.  The University of Iowa is not responsible for demonstrations performed by those using their own equipment or who choose to use this reference material for their own purpose.  The demonstrations included here are within the public domain and can be found in materials contained in libraries, bookstores, and through electronic sources.  Performing all or any portion of any of these demonstrations, with or without revisions not depicted here entails inherent risks.  These risks include, without limitation, bodily injury (and possibly death), including risks to health that may be temporary or permanent and that may exacerbate a pre-existing medical condition; and property loss or damage.  Anyone performing any part of these demonstrations, even with revisions, knowingly and voluntarily assumes all risks associated with them.