Higher harmonics from a 2013 GJ 674 orbit fit reduce 2014 residual error by 3.7 percent

We test whether higher harmonics of the known GJ 674 velocity signal help separate an eccentric orbit from two circular signals at a 2:1 period ratio. An orbit fit to 58 HARPS-RVBank version 02 exposures in 2013 predicts the harmonics above twice the orbital frequency. After reference terms are removed, this prediction has an RMS of 0.213 m/s in 67 exposures in 2014. It reduces weighted residual squared error by 3.67 percent. Its fitted scale is 1.58. All nine conditional sign perturbation ranges include zero. One-sided block sign tail fractions are 0.044 to 0.107. Thus the evidence does not reliably separate these models under the tested noise rules. Other velocity reductions and baseline choices give small positive gains. They share spectra. No new planet is found and no independent instrument confirms the higher harmonics. Code, exact input, hashes, figures and an independent Bessel-series check are included.

astronomy · GJ 674 · HARPS · eccentricity · orbital harmonics · 2:1 degeneracy · null result