meepmeep.numba3d.rv_c

meepmeep.numba3d.rv_c(time: float | ndarray[tuple[Any, ...], dtype[_ScalarT]], k: float, p: float, a: float, i: float, e: float, c: ndarray[tuple[Any, ...], dtype[_ScalarT]]) → float | ndarray[tuple[Any, ...], dtype[_ScalarT]]

Evaluate the stellar radial velocity induced by the planet at an expansion-point-centered time.

Converts the planet’s centered line-of-sight velocity into the physical radial velocity of the host star, scaled by the user-supplied semi-amplitude k. The conversion follows Perryman (2018) Eq. 2.23.

Parameters:

timefloat or NDArray

Time relative to the Taylor series expansion point.

kfloat

Radial-velocity semi-amplitude of the star, in physical velocity units (e.g. m/s). The function output inherits these units.

pfloat

Orbital period.

afloat

Scaled semi-major axis in units of stellar radii.

ifloat

Orbital inclination in radians.

efloat

Orbital eccentricity.

cNDArray

A (3, 5) coefficient matrix produced by solve3d. Only row 2 (the z-direction coefficients) is read by the inner zvel_c.

Returns:

rvfloat or NDArray

Stellar radial velocity in the same units as k. The sign convention matches the underlying z-axis: positive when the planet (and therefore the reflex motion of the star) is directed toward the observer.

Notes

The normalisation factor n = (2*pi/p) * (a * sin(i)) / sqrt(1 - e^2) has units of inverse time times stellar radii, exactly cancelling the units of the scaled vz so that vz / n is dimensionless and the final multiplication by k carries the physical units.