Why do we say that the Doppler technique gives the planet's "minimum mass"?
A)The size of the Doppler shift that we detect depends on whether the planet's orbit is tilted.
B)The size of the Doppler shift that we detect depends on knowing the star's mass,which can be very uncertain.
C)Extrasolar planets are always increasing in mass.
D)Doppler measurements are very difficult,producing noisy data that often cause astronomers to underestimate a planet's mass.

Question

Quizplus · Accepted Answer

The Doppler shift only tells us the component of the planet's velocity that is along our line of sight. If the planet's orbit is tilted (i.e., not edge-on), we only see part of its true velocity, leading to an underestimation of its mass. The actual mass could be greater, depending on the tilt of the orbit.

Why Do We Say That the Doppler Technique Gives the Planet's