Description

This program simulates the detection of exoplanets by using the radial velocity method and the Doppler effect. In this simulation the exoplanet orbits the star (sun-sized) in circular motion via Kepler's third law. The radial velocity of the star is determined from the velocity of the exoplanet. This velocity is then used to calculate the Doppler shift of the Fraunhofer lines of the star. In practice it is the Doppler shift of the Fraunhofer lines of the star that are detected and from this the radial velocity is inferred. From this the mass and orbital period and average exoplanet-star separation are determined.

In the simulation the star-exoplanet system is shown as seen from Earth (edge on view) and from space (overhead view), and with the star and exoplanet sizes not shown to the scale of the orbit. In addition, the Fraunhofer lines are shown. The radial velocites of stars are such that the Doppler shifts are small, to compensate you may snap to the Na line and use the right-hand side slider to zoom in on that line to see wavelength shift.