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

An exponential noise model reduces support for the 414-day component in GJ 273 CARMENES DR1

We test two proposed outer periods in public CARMENES DR1 velocities of GJ 273. We form 196 nightly means from 731 accepted exposures. We fit free phases and circular amplitudes at 413.9 and 541.5 days. Two inner components, an offset, and a trend are also fitted. With independent Gaussian nightly errors, the separate likelihood gains are 16.25 and 35.74. With a fitted exponential covariance, they fall to 4.17 and 11.21. For the 414-day test, 270 of 1000 draws from the fitted correlated null model exceed the observed gain. The covariance has amplitude 1.62 m/s and decay time 19.25 days. It improves the full-model AIC by 34.05. The fitted outer amplitudes change from 1.04 and 1.75 m/s to 0.98 and 1.82 m/s, while conditional uncertainty grows. Activity terms, annual terms, and removal of dense observing nights cause smaller changes under independent errors. Thus, support for a separate 414-day component is sensitive to the error model. The 542-day component retains more support in the fitted correlated model. These fixed-period, free-phase tests do not confirm or exclude outer planets. The package preserves nightly data, source hashes, code, figures, simulation results, and reproduction commands.

GJ 273 · Luyten star · CARMENES DR1 · radial velocity · planet candidates · correlated noise · fixed periods · nightly means · independent instrument test · reproducible analysis

Admitted 1 citing publication

References

8
  1. usesdoi:10.1051/0004-6361/202244879

    CARMENES DR1 supplies the source velocities and activity indices. Table 7 already reports unresolved long-period variation and a 95-day rotation entry for this star.

  2. usesdoi:10.48550/arXiv.1906.04644

    Version 2, Appendix A.16, supplies the tested periods and source amplitudes. We test free-phase circular components rather than its full orbit predictions.

  3. doi:10.1051/0004-6361/201630153

    The inner-planet study supplies prior context. A control uses its 18.6498-day inner period.

  4. doi:10.5281/zenodo.438330

    This thesis already studied early CARMENES observations of GJ 273 and unexplained variation near 400 to 500 days.

  5. doi:10.1051/0004-6361/202038047

    This study discusses formation and dynamics of the proposed system.

  6. doi:10.53846/goediss-11478

    Chapter 4 gives a prior multi-instrument study of GJ 273 with correlated noise and wavelength tests. Its conclusions limit the new contribution here to the supplied exact DR1 calculation.

  7. 14 CARMENES observations support the fixed signal at 19.466 days in GJ 720 A under Gaussian white noise sci:sha256:005ffaecc375fa7f484be904a4d879760efec2d5c9af04c98fe8bcbfca983482

    This test of GJ 720 A informed the independent-instrument approach. We do not reuse its code or data.

  8. Four of five fixed HARPS candidate curves disagree with CARMENES DR1 under a 90-day block error model sci:sha256:e8c306d84e6b5d0e3fc719a5eb2c079a80ff6c319d10463c832d06dcd0ad3f9d

    This study tests other stars and checks DR1 numerical units. It informed source selection. We wrote separate code and use a different free-phase test.

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