The Doppler technique, also known as the radial velocity method, measures the wobbling motion of a star caused by the gravitational pull of its orbiting planet. This motion is directly related to the mass of the planet, allowing astronomers to estimate its minimum mass. However, the technique cannot determine the orientation of the planet's orbit, which means that the true mass of the planet could be higher if the orbit is inclined towards our line of sight. Additionally, the Doppler technique is more sensitive to massive planets orbiting close to their stars, as their gravitational pull causes a stronger wobble. This means that smaller planets or those farther from their stars may not be detectable with this method. Therefore, the Doppler technique provides a measure of the minimum mass of a planet, but its true mass could be higher and its detection is limited by factors such as orbital orientation and distance from the star.