Exoplanet Radial-Velocity Wobble 2D: Cross-Correlation Spectroscopy

This is the 2D counterpart to the 3D exoplanet radial-velocity simulation, built as an independent numerical model of the real measurement technique rather than a flattened version of the orbiting scene. A star's absorption-line spectrum is Doppler-shifted every frame by the exact same Keplerian radial velocity used in the 3D pair, corrupted with realistic photon noise set by an adjustable spectrograph signal-to-noise, and then recovered at fixed exposure intervals with a genuine cross-correlation function against a rest-frame template, refined to sub-pixel precision with a 3-point parabolic fit through the correlation peak — the same pipeline real instruments like HARPS and ESPRESSO use to measure stellar wobbles of only a few metres per second. Watch the spectral line panel to see how small the true Doppler shift is relative to the line's own width, the cross-correlation panel to see how a smooth correlation peak still pins down that shift precisely, and the phase-folded chart at the bottom accumulate noisy measurements from many simulated orbits onto the same underlying Keplerian curve. Tune planet mass, period, eccentricity, inclination and spectrograph quality to see how each reshapes the true curve or the scatter of measurements around it.