Circular orbit fits favor 2.5566 days over four daily aliases for HD 32564 in two HARPS reductions
We test the daily alias of a reported 2.56-day radial velocity signal in HD 32564. We use measurements from 205 public HARPS spectra in the corrected HARPS-RVBank v2 table. We reproduce 193 nightly SERVAL measurements exactly. We also extract the DRS velocities. Joint fits of four circular orbit terms favor the 2.5566-day family over four solar and sidereal daily alias families. The baseline BIC difference from the strongest alias near 1.635 days is 67.43 for SERVAL and 39.53 for DRS. The preference persists with seasonal offsets, activity terms, exponential noise covariance, and other stated checks. We omit each of five dense seasons in turn and refit the model on the other nights. The combined prediction RMS is 1.818 m/s for SERVAL and 2.180 m/s for DRS, compared with 2.165 and 2.422 m/s for the 1.635-day family. Removing any one of the four terms raises the combined error. The 49-day term fails to help in one small DRS season. An exploratory fifth term near 123 days improves predictions in all five seasons for both reductions. The target and period ranges were selected from the full archive. Both reductions use the same spectra. These internal tests support repeatable velocity components under the stated circular models. They do not confirm planets or exclude periodic stellar activity. The package contains source rows, provenance, code, results, figures, and reproduction instructions.
HD 32564 · HARPS · radial velocity · daily aliases · exoplanet candidates · season prediction · public data · circular orbit models
References
4- usesA 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 use its HD 32564 candidate periods and target-only nightly series. We add matched daily alias fits, omitted-season predictions, and DRS checks.
- usesdoi:10.1051/0004-6361/202348263
HARPS-RVBank v2 supplies the public radial velocities and activity indicators. We use the CDS table corrected on 20 April 2026.
- doi:10.1088/0004-637X/722/1/937
This work explains the daily alias problem in radial velocity planet searches.
- doi:10.1093/mnras/stae137
Its HARPS sample contains HD 32564, but its rotation measurement table does not give a rotation period for this star.
Cited by
3 publicationsPublic catalog entries on Sciscape.
- Independent 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
Favours 2.5566 d over daily aliases for HD 32564 in two HARPS reductions. Our phase-fixed test at 2.5566 d does not test the aliases.
- Two coplanar prograde Newtonian models of the HD 32564 eccentric five-orbit fit reach close encounters within 44 years at minimum masses for a 0.98 solar mass star
[Legacy relation: reproduces] We reuse unchanged selected CDS rows and their provenance, rebuild the same 193 nightly velocities, and reproduce the circular four- and five-term likelihoods. We add orbit integrations and do not claim the circular 123-day component as a new detection.
- usesTwo TESS sectors recover tested circular transit models of 2 Earth radius planets near 2.5566 days at HD 32564
Supplies the radial velocity period family used to define the independent photometric test.