meepmeep.numba3d.ev_signal_c

meepmeep.numba3d.ev_signal_c(time: float | ndarray[tuple[Any, ...], dtype[_ScalarT]], alpha: float, mass_ratio: float, inc: float, c: ndarray[tuple[Any, ...], dtype[_ScalarT]]) → float | ndarray[tuple[Any, ...], dtype[_ScalarT]]

Evaluate the ellipsoidal-variation signal at an expansion-point-centered time.

Centered counterpart of ev_signal: assumes time has already been shifted to be relative to the expansion point. Returns the relative flux variation induced by the tidally distorted primary (Lillo-Box et al. 2014, Eqs. 6-10), \(S = -\alpha\,q\,\sin^2 i\,(2 c_z^2 - 1)/d^3\) with \(c_z = z/d\) and \(d = \sqrt{x^2 + y^2 + z^2}\) the instantaneous 3D star-planet distance in stellar radii.

Accepts a scalar time or a 1-D array of times and dispatches to the appropriate kernel at compile time (inside @njit) or at call time (pure Python).

Parameters:

timefloat or NDArray

Time relative to the Taylor series expansion point.

alphafloat

Gravity-darkening coefficient (Lillo-Box et al. 2014, Eq. 7).

mass_ratiofloat

Planet-to-star mass ratio \(M_p / M_\star\).

incfloat

Orbital inclination [radians]. Enters only through the \(\sin^2 i\) projected-area factor.

cNDArray

A (3, 5) coefficient matrix produced by solve3d.

Returns:

evfloat or NDArray

Relative flux variation due to ellipsoidal distortion. Shape (N,) for an array time.

Notes

Uses the identity \(\cos(2\arccos u) = 2u^2 - 1\) to skip a redundant arccos/cos pair.