Astrophysics (Index)About

Kepler radius

(radius at which a particular velocity would orbit)

Kepler radius and similar term Keplerian radius are terms I can find no definition for.

I speculate it might be the radius of a Keplerian orbit that would produce a given observation: for example, if apparent the Doppler shift of spectral lines of a disk (e.g., circumstellar disk), planet, or binary star companion indicate radial velocities implying some orbital speed, the Kepler radius would be the radius suggested by Kepler's laws.

Another possible use, for a disk in which other forces contribute to the orbital speeds (e.g., gas pressure, radiation pressure), would be a radius of the disk at which those other forces cancel and the orbital speed is that of a Keplerian orbit.

The phrase also arises with a totally unrelated meaning: in discussion of Kepler Telescope discoveries, e.g., Kepler radius distribution, which could be the distribution of extra-solar planet radii in samples of Kepler discoveries.