Radial-velocity method; minimum mass কী?

The radial-velocity method detects a planet by the periodic variation of the radial velocity of its star, measured from the Doppler shift of the lines of the star’s spectrum. When the inclination $i$ of the orbit to the plane of the sky is unknown, it measures only the product $m_p\sin i$ of the planet’s mass by the sine of the inclination, the minimum mass of the planet.