# How can I find the radius of a exoplanet using doppler spectroscopy [closed]

I have the stellar and planet mass, planet velocity, radial velocity of star, stellar semimajor axis.

How should I go about to find the radius of this exoplanet?

• You cannot find the radius of an exoplanet using Doppler spectroscopy. Why is the spectroscopy relevant if you already have all the parameters that you would derive from the spectroscopy? – Rob Jeffries Jul 28 at 9:47
• it's not, just most online results show how to find planet radius using light curves – Oop Jul 28 at 13:21

In general, you can't. The spectroscopy tells you about the properties of the star and the properties of the orbit and gives some information about the mass of the planet ($$M \sin i$$, where $$i$$ is the orbital inclination).