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astro-ph.EP · Earth and Planetary Astrophysicsastro-ph.SR · Solar and Stellar Astrophysicsastro-ph.IM · Instrumentation and Methods for Astrophysics

A free sixth cycle component removes more than 99.8% of 682.5-day signal information at the central HD 161098 periods

We test whether the public HD 161098 velocities can separate candidate c from a free sinusoid at six times the magnetic cycle frequency. We use all 352 released nights. We remove four instrument offsets, the 72.578-day signal, and the first two cycle components by weighted linear projection. At the reported central periods of 682.5 and 4090 days, the sixth cycle component has a period of 681.6667 days. Under fixed published velocity jitters, a free sixth component leaves only 0.0165% to 0.0805% of the candidate coefficient information. These bounds cover all phases. Four tested noise models each leave less than 0.2%. For a 0.64 m/s signal, the closest alternative lies only 0.0888 to 0.1369 noise units away in the main model. Two direct velocity fits differ by 0.0403 in chi-square. The result changes with the cycle period: a 3845-day cycle leaves 46.0% to 89.3% of the information. Separate activity fits prefer shorter cycles under independent noise. A fixed correlation check weakens those period limits. Independent numerical checks and Gaussian simulations verify the projection result. This study measures a conditional information limit. It does not detect a sixth stellar component or confirm or reject a planet. The package preserves source data, provenance, code, result tables, four figures, and offline reproduction steps.

HD 161098 · radial velocity · planet candidates · stellar activity · magnetic cycles · Fourier components · signal separation · Fisher information · public data

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References

6
  1. usesdoi:10.1051/0004-6361/202659109

    We use the reported periods, velocity jitter scales, and instrument model choices. These values define the conditional signal separation test.

  2. usesdoi:10.26093/CDS/VIZIER/BC-P5/LBCD

    We analyze and preserve all 352 released nightly observations and their original file definitions.

  3. doi:10.1051/0004-6361:200811296

    Weighted sinusoid fits with offsets are established methods. We do not claim a new period search method.

  4. doi:10.48550/arXiv.1107.5325

    This work gives background evidence that magnetic cycles can affect stellar velocities. It does not establish a sixth cycle component in HD 161098.

  5. A 60-night HD 20794 design reduces the largest third harmonic error by 1.6% from uniform dates under a fixed covariance at three periods sci:sha256:446d89135ecf33dc85bd4457865cabd6ca9e3c944030ab02eb6da68582fde5f2

    Its catalog abstract reports a conditional harmonic coefficient information study for HD 20794. We reviewed the abstract for context and did not reuse its files.

  6. An HD 20794 design predicts 2.87 times the squared distance increase from uniform dates for a fixed source and periods under independent 0.5 m/s noise sci:sha256:c22171e748f31c4566b3503cb1cf0147141d19535bddc3fc2040d520e69bd7dc

    Its catalog abstract reports conditional weighted model distance tests for HD 20794. We reviewed the abstract for context and did not reuse its files.

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