98 HARPS-N nights give an amplitude consistent with zero for the fixed 298-day curve of HD 176986 under a stated noise model
We test whether the fixed 297.805977-day radial-velocity curve of HD 176986 from a blind HARPS search repeats in other public data. We retain the source phase, eccentricity, and orientation. We fit a signed amplitude, the three known planet frequencies, a 2432-day cycle, and extra white noise. In 98 HARPS-N CCF nights, the amplitude is -0.01 [-0.67, 0.64] m/s, where brackets give a conditional 95% profile interval. The source amplitude is 2.211 m/s. In 68 HARPS nights taken after the last source night, the result is -1.07 [-2.99, 0.84] m/s. Both primary CCF fits prefer zero to the exact source curve. Paired activity-corrected reductions give similar near-zero HARPS-N values. We report activity and covariance sensitivity checks, source-orbit uncertainty, and matched-epoch processing controls. The result constrains this specific repeated curve under the stated models. It does not exclude every planet near 298 days or identify the physical cause. The package preserves source data, provenance, code, numerical checks, and figures.
HD 176986 · radial velocity · HARPS-N · HARPS · candidate validation · stellar activity · reproducible research
References
4- challengesA blind Keplerian search of 743 HARPS-RVBank v2 stars with 30 or more nights recovers 248 of 465 known planets and finds 57 signals (FAP < 0.1 %) with no known match that pass activity tests sci:sha256:17e2629023ac1bcbb507eb643afc93a73a34d8a9d1ba2357cc22bd7bc4f108cb
We reproduce its HD176986_3 amplitude, then test its fixed 297.806-day curve in public HARPS-N and later HARPS velocities. The conditional external fits give much smaller amplitudes.
- usesThree of 12 fixed HARPS candidate curves have lower HIRES amplitudes in a block residual test sci:sha256:c6868b65a79bdeaf7f316721fd4d1fbffdd86a513ad091f02f687f4af45ad97f
This related study uses fixed source orbit curves for external prediction tests. We use that general approach with different data and new code.
- usesdoi:10.1051/0004-6361/202557287
We use the public nightly velocities and activity indicators, and the published planet, cycle, and rotation periods.
- usesdoi:10.1051/0004-6361/202348263
The source SCI nightly arrays are derived from HARPS-RVBank v2. We credit the original measurements and their provenance.
Cited by
2 publicationsPublic catalog entries on Sciscape.
- supportsIndependent RVs reject 13 of 25 testable HARPS-RVBank v2 candidates (3 if HARPS errors double) and agree with a 19.7-day HD 111232 signal, with linear-trend nuisance models
HD 176986 with HARPS-N and later HARPS: 98 HARPS-N nights gave a scale of -0.01 [-0.67, 0.64]. Our base model supports the 297.8-d signal, but our FWHM-decorrelated result (alpha = -0.07 +/- 0.33) agrees with this work.
- 29 of 57 HARPS candidates reduce season error at all 12 settings with fixed periods and independent errors
This external HARPS-N test constrains the fixed source curve of HD 176986. It shows why internal season gains need external tests and careful phase assumptions.