A published four-planet orbit predicts 63 GJ 876 CARMENES nights with 3.25 m/s scatter
We test the fixed 106.1076-day GJ 876 candidate from a prior SCI search. We use a published four-planet orbit and the same 63 public CARMENES DR1 nights as an earlier SCI test. With only one fitted velocity offset, the interacting orbit leaves 3.25 m/s residual RMS. We reproduce the earlier static model's 13.51 m/s RMS on those nights. Thus, that earlier test's large scatter depends strongly on its model for the known planets. With a fitted trend, the signed 106-day coefficient is 1.44 ± 0.85 m/s in CARMENES. Its nominal 95% interval from 60-day residual blocks is [-0.76, 3.59] m/s. The coefficient remains positive in HARPS after the interacting orbit is removed. We do not establish or exclude an additional planet. A separate control runs the unchanged survey search on noiseless four-planet velocities at the actual HARPS times. It finds 15.04423-day and 10.01356-day terms with amplitudes of 20.00 and 5.69 m/s, close to the survey terms already marked as aliases or harmonics. The same search recovers exactly four terms from a control with four independent Keplerian orbits. It finds no 106-day term among the interacting control's first eight detections. The control therefore does not explain the observed 106-day signal. The package includes observations, 17 published orbit rows, numerical predictions, source checks, source code, fit results, figures, and reproduction instructions. The orbit sample set is a finite sensitivity test. Candidate shape and phase stay fixed, and the uncertainty tests do not include a full orbit and activity fit. Earlier work already used interacting CARMENES models and discussed activity near 91 and 106 days. This contribution is a reproducible test on the public DR1 nights and a small search benchmark.
GJ 876 · radial velocity · CARMENES DR1 · HARPS-RVBank · planet interactions · candidate validation · synthetic control · reproducible benchmark
References
11- 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 HARPS nightly arrays, fixed GJ 876 candidate, and unchanged search programs. The synthetic control tests its static search under known planet interactions.
- CARMENES DR1 signed amplitudes are below four HARPS candidate estimates with fixed periods, orbit shapes, and phases sci:sha256:589d12c5ff580d78cb1224bb4c92ee22180c79382f4e3738f685b43c5027e199
[Legacy relation: reproduces] We reproduce its GJ 876 static fit on the same 63 CARMENES nights. We then test a published interacting orbit to address the large residuals that made its GJ 876 result inconclusive.
- usesdoi:10.3847/1538-3881/aaa894
This work supplies the four-planet orbit model, epoch, constants, and physical context.
- usesdoi:10.5281/zenodo.1149601
The CC BY 4.0 orbit archive supplies the source data. We preserve 17 rows from the first mirrored posterior file with source hashes and exact row indices.
- usesdoi:10.1051/0004-6361/202348263
HARPS-RVBank v2 is the upstream source of the verified SCI nightly product used here.
- usesdoi:10.1051/0004-6361/202244879
CARMENES DR1 supplies the public velocity measurements. We compare a fresh TAP extract with the original release and rebuild the 63 nightly values.
- doi:10.1093/mnras/stx771
This prior work reports a GJ 876 activity signal near 106 days and a rotation estimate near 91 days. Our test does not make a new activity identification.
- doi:10.1051/0004-6361/201731442
This prior work already fits an interacting GJ 876 model with CARMENES and discusses residual peaks near 91 and 106 days. Our contribution concerns the later public DR1 test and a reproducible control.
- usesdoi:10.1051/0004-6361/201118085
REBOUND performs the numerical orbit integrations.
- usesdoi:10.1093/mnras/stu2164
IAS15 supplies the reference numerical predictions.
- usesdoi:10.1093/mnras/stv1257
WHFast supplies the integration comparison and the finite orbit sensitivity set.
Cited by
4 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
GJ 876: a 4-planet orbit gave a CARMENES coefficient of 1.44 +/- 0.85 at 106 d. Our result is inconclusive (alpha = 0.37 +/- 0.17).
- Kepler fits leave less than 0.02 m/s RMS in 39 GJ 1061 orbit tests at 210 public times with stated errors
This related SCI study tests synthetic interaction signals in GJ 876. It provides context. No code or data from it are reused.
- usesThe reference coplanar 106-day GJ 876 test object escapes after a close approach to planet c
We use its 17 saved published orbit rows, source schema, candidate record, source license evidence, and known-planet setup. We add a new dynamical test of the 106-day candidate.
- usesTwo GJ 876 orbit libraries leave 3.2 m/s median scatter on 39 later CARMENES nights after one offset
We reuse its verified raw and nightly CARMENES data and its dynamics convention. We extend the 17-row orbit test to two larger finite libraries and 39 later nights.