Binary stars simulation using smartphones — A Doppler effect experiment

Abstract

We present a simple experiment to simulate a binary star system to study the Doppler effect using two smartphones and a PC. The smartphones mounted on a rotating bar are used as monochromatic sound sources. A microphone connected to a PC records these signals in the lab frame of reference. The Doppler effect is readily observed, and the experimental results can quantitatively be compared to the expectation of a theoretical model. This experiment can simulate the Doppler Spectroscopy technique used to measure radial velocities and masses in rotating binary stars and the exploration of exoplanets. The set-up is low-cost and simple to construct and understand. The experiment can be carried out at home or in a regular laboratory setting.