Space Astronomy Doppler effect

Doppler Spectroscopy (Radial Velocity Method)

• Indirect method for finding exoplanets
• Measure radial velocity via observation of doppler shifts in the spectrum of the planet's parent star
  • If a planet exists, the gravity of the planet causes the star to wobble
• If a planet is detected, a minimum mass for the planet can be determined from the changes in the star's radial velocity
  • More precise measurements require the inclination of the planet's orbit
• Can tell us the orbital period of the planet
• Most sensitive to large planets orbiting close to the star

Procedure

• Series of observations of the electromagnetic spectrum emitted by a star
• Periodic variations in the star's spectrum may be detected
  • Wavelength of characteristic spectral lines increasing and decreasing over time
• Astronomers use math to isolate a sine wave that indicates a planet in orbit