From Doppler to exoplanets

In this exercise, we explain how an invisible planet can be unveiled using precise measurement of the velocity of its mother star. The radial-velocity method uses the fact that a star with a planet will move in its own small orbit in response to the planet's gravity. The goal is to measure variations in the speed with which the star moves toward or away from Earth. The radial velocity can be deduced from the displacement in the parent star's spectral lines due to the Doppler effect, as shown in the upper animation.

  Exercice proposed by :
Roger FERLET, Institut d’Astrophysique de Paris, France
Michel FAYE, lycée Louis Le Grand , Paris , France
Suzanne FAYE, Lycée Chaptal , Paris , France

Summary :

1. SPECTROSCOPY
2. ANIMATED MOTION OF SPECTRUM LINES
3. MEASURE WAVELENGTH λ AND FLUX, OPTICAL SPECTRUM
4. CALCULATING  RADIAL VELOCITY OF THE STAR WITH DOPPLER SHIFT
5. RADIAL VELOCITY OF THE STAR , AS A FUNCTION OF DATE
6. DETERMINING THE MASS OF THE COMPANION IN BINARY SYSTEM
7. DISCOVERING AN EXOPLANET WITH DOPPLER SHIFT OF A STAR

Download the exercise :  pdf 317.75 Kb

Download the data (zip file): exoplanet_doppler 541.04 Kb