Which of the following statements regarding the Doppler method of exoplanet detection are correct? (Select all that apply.)
a. The Doppler method involves measuring Doppler shifted light from a planet. Because the planet moves around the star in its orbit, light reflected from the planet will be both red- and blue-shifted.
b. The Doppler method requires the careful measure of the intensity of different wavelengths in the spectrum of a star, because the presence of a planet around a star will affect its brightness.
c. The Doppler method involves measuring Doppler shifted light from a star. If there are planets in orbit around a star, their gravity will pull on the star and cause it to move.
d. The Doppler method relies on measuring very small shifts in the position of absorption lines in a spectrum.