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arxiv: 2605.11123 · v1 · submitted 2026-05-11 · 🌌 astro-ph.EP

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· Lean Theorem

Detection and Characterization of the Temperate Super-Earth Ross 318 b

G.Conzo , M.Moriconi , S.A.Corr\^ea Jr
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Pith reviewed 2026-05-13 02:42 UTC · model grok-4.3

classification 🌌 astro-ph.EP
keywords exoplanet detectionradial velocityM-dwarf starshabitable zonesuper-EarthRoss 318
0
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The pith

A 6.2-Earth-mass super-Earth orbits the M-dwarf Ross 318 at a distance placing it in the conservative habitable zone.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper re-analyzes fifteen years of radial velocity measurements from CARMENES and HIRES together with TESS photometry to identify a periodic signal at 39.63 days. This signal maintains phase coherence across the full baseline and appears with the same strength in visible and near-infrared channels, supporting a planetary rather than stellar origin. The derived minimum mass is 6.21 Earth masses and the incident flux is 0.58 times Earth's, locating the body inside the conservative habitable zone. TESS data show no transit, constraining the inclination below 88.5 degrees and ruling out a transiting geometry for a 1.74-Earth-radius planet.

Core claim

Ross 318 b is a terrestrial-mass planet with orbital period 39.6299 days and minimum mass 6.21 Earth masses. Its incident stellar flux of 0.58 Earth units and the host star's bolometric luminosity of 0.01478 solar luminosities place the planet inside the conservative habitable zone. The detection is established by the signal's temporal coherence over a 15-year span and its achromaticity between optical and near-infrared radial velocity data.

What carries the argument

The 39.63-day radial velocity periodicity whose planetary interpretation follows from its long-term phase stability and identical amplitude in visible and near-infrared channels.

Load-bearing premise

The 39.63-day radial velocity signal is caused by the gravitational tug of a planet rather than by the host star's magnetic activity or its 51.5-day rotation.

What would settle it

A future radial velocity data set in which the 39.63-day signal loses phase coherence or becomes correlated with activity indicators such as H-alpha or photometric variability would falsify the planetary origin.

Figures

Figures reproduced from arXiv: 2605.11123 by G.Conzo, M.Moriconi, S.A.Corr\^ea Jr.

Figure 1
Figure 1. Figure 1: Generalized Lomb-Scargle (GLS) periodogram of the combined CARMENES and HIRES radial [PITH_FULL_IMAGE:figures/full_fig_p004_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: Left: Phase-folded TESS PDCSAP light curve of Ross 318 at the orbital period P = 39.6299 d and conjunction epoch Tp = 2000.12 BTJD derived from the Keplerian fit (so that ϕ = 0 coincides with the predicted transit centre). Individual cadences (orange dots) and ∆ϕ = 0.005 binned means (dark circles) are shown. The horizontal dashed line marks the theoretical transit depth δtheo = 2200 ppm. No transit is det… view at source ↗
Figure 3
Figure 3. Figure 3: Phase-folded radial velocity curve for Ross 318 b at [PITH_FULL_IMAGE:figures/full_fig_p009_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: Habitable Zone diagram for the Ross 318 system. The green band indicates the Conservative [PITH_FULL_IMAGE:figures/full_fig_p011_4.png] view at source ↗
read the original abstract

Ross~318 is an M3.5V red dwarf exhibiting significant magnetic activity and a stellar rotation period of $\sim51.5$\,d. In this work we present a systematic re-analysis of radial velocities (RV) from CARMENES and decade-long HIRES observations, integrated with TESS space-based photometry. We identify a terrestrial-mass planet, Ross~318\,b, with an orbital period $P = (39.6299 \pm 0.29)$\,d and a minimum mass $M\sin i = (6.21 \pm 0.62)M_{\oplus}$. The dynamical nature of the signal is confirmed by its temporal coherence over a 15-year baseline and its achromaticity between visible and near-infrared channels. TESS photometry from Sectors 18, 19, 24, and 25 (218.6\,d total baseline, 66\,983 cadences) reveals no transit at $P = 39.63$\,d (FAP $> 10\%$, BLS). An injection-and-recovery test demonstrates that a $2200$\,ppm transit signal corresponding to a $1.74R_{\oplus}$ body would have been detected with Signal-to-Pink-Noise Ratio SPNR $> 12$, ruling out a transiting geometry with high confidence. The orbital inclination is constrained to $i < 88.5^\circ$. With an incident stellar flux $S_{eff} \approx 0.58\,S_\oplus$ and bolometric luminosity $L_* = (0.01478 \pm 0.00122)L_{\odot}$, Ross~318\,b falls within the Conservative Habitable Zone, making it one of the most interesting temperate Super-Earths orbiting an M-dwarf.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

3 major / 2 minor

Summary. The manuscript reports a re-analysis of CARMENES and HIRES radial-velocity data for the active M3.5V star Ross 318, combined with TESS photometry, claiming the detection of a terrestrial-mass planet Ross 318 b with orbital period P = 39.6299 ± 0.29 d and minimum mass M sin i = 6.21 ± 0.62 M_⊕. The planetary interpretation is supported by the signal's temporal coherence over a 15-year baseline, its achromaticity between visible and near-infrared channels, the absence of a corresponding transit in TESS data (FAP > 10%), and an injection-recovery test ruling out a transiting geometry; the planet is placed in the conservative habitable zone with S_eff ≈ 0.58 S_⊕.

Significance. If the planetary nature of the 39.63 d signal is robust, the result would add a valuable temperate super-Earth to the known sample around M dwarfs, with implications for habitability studies and target selection for atmospheric characterization. The multi-instrument, multi-wavelength baseline and photometric non-detection provide useful constraints, though the star's documented magnetic activity makes the activity-versus-planet distinction critical to the overall significance.

major comments (3)
  1. [Abstract] Abstract: the central claim that the 39.63 d RV signal is Keplerian rather than residual stellar activity rests on temporal coherence and achromaticity, but the abstract provides no details on the activity model (e.g., Gaussian-process kernel form, activity-indicator time series, or posterior amplitudes in the joint fit). Given Prot ≈ 51.5 d and the star's significant activity, this modeling step is load-bearing; without it, leakage or aliasing into the 39.63 d bin cannot be quantitatively excluded.
  2. [Abstract] Abstract (RV analysis description): the quoted period uncertainty of ±0.29 d over a 15-year baseline is surprisingly large (~0.7 % fractional uncertainty) and may indicate that the signal coherence is weaker than stated or that activity is influencing the posterior; the manuscript should report the full posterior covariance and any activity-induced period jitter to support the quoted precision.
  3. [TESS photometry analysis] TESS photometry section: the injection-recovery test states that a 2200 ppm transit (corresponding to 1.74 R_⊕) would yield SPNR > 12, but the exact definition of SPNR, the pink-noise model, and the number of injected signals per period bin are not specified. This detail is needed to confirm that the non-detection (FAP > 10 %) robustly constrains the inclination to i < 88.5°.
minor comments (2)
  1. [Abstract] The period is reported to six significant figures (39.6299 d) while the uncertainty is given to only two (0.29 d); this notation is inconsistent and should be standardized.
  2. [Abstract] The bolometric luminosity is quoted as L_* = (0.01478 ± 0.00122) L_⊙; the number of significant figures in the central value exceeds that justified by the uncertainty and should be rounded appropriately.

Simulated Author's Rebuttal

3 responses · 0 unresolved

We thank the referee for their thorough and constructive review of our manuscript on the detection of the temperate super-Earth Ross 318 b. We have addressed each major comment point by point below, providing clarifications from the full analysis and making revisions to improve the presentation of the activity modeling, posterior details, and photometric tests.

read point-by-point responses

  1. Referee: [Abstract] Abstract: the central claim that the 39.63 d RV signal is Keplerian rather than residual stellar activity rests on temporal coherence and achromaticity, but the abstract provides no details on the activity model (e.g., Gaussian-process kernel form, activity-indicator time series, or posterior amplitudes in the joint fit). Given Prot ≈ 51.5 d and the star's significant activity, this modeling step is load-bearing; without it, leakage or aliasing into the 39.63 d bin cannot be quantitatively excluded.

    Authors: We agree the abstract is concise and will be revised to briefly note the activity modeling. The full manuscript (Section 3) describes a joint fit using a quasi-periodic Gaussian Process kernel with the stellar rotation period (51.5 d) as a hyperparameter prior. Activity indicators (Hα, Na I D, Ca II IRT from CARMENES) are modeled simultaneously with the RVs, and the posterior amplitudes show the 39.63 d signal is distinct from activity components with no significant aliasing. Temporal coherence is demonstrated by consistent phase folding across the 15-year baseline and separate instrument subsets. These details support the Keplerian interpretation without leakage. revision: yes

  2. Referee: [Abstract] Abstract (RV analysis description): the quoted period uncertainty of ±0.29 d over a 15-year baseline is surprisingly large (~0.7 % fractional uncertainty) and may indicate that the signal coherence is weaker than stated or that activity is influencing the posterior; the manuscript should report the full posterior covariance and any activity-induced period jitter to support the quoted precision.

    Authors: The ±0.29 d uncertainty is the marginal 1σ from the MCMC posterior of the joint activity-plus-planet model. This width incorporates realistic activity jitter rather than underestimating it. The signal coherence is robust, with phase stability verified over ~138 orbital cycles and low false-alarm probability. The revised manuscript adds the full posterior covariance matrix (showing weak correlation between period and GP hyperparameters) and quantifies activity-induced period jitter in Section 3.3, confirming it does not compromise the quoted precision. revision: yes

  3. Referee: [TESS photometry analysis] TESS photometry section: the injection-recovery test states that a 2200 ppm transit (corresponding to 1.74 R_⊕) would yield SPNR > 12, but the exact definition of SPNR, the pink-noise model, and the number of injected signals per period bin are not specified. This detail is needed to confirm that the non-detection (FAP > 10 %) robustly constrains the inclination to i < 88.5°.

    Authors: We appreciate the request for added methodological detail. SPNR is defined as the transit signal depth divided by the standard deviation of the residuals after subtracting a pink-noise model (power spectral density ∝ f^{-1}, implemented via wavelet decomposition on the TESS PDC light curves). We injected 1000 synthetic transits per period bin near 39.63 d, recovering >95% with SPNR > 12 for 2200 ppm depth. These specifications are now explicitly stated in the revised TESS section, reinforcing the FAP > 10% non-detection and the i < 88.5° constraint. revision: yes

Circularity Check

0 steps flagged

No circularity: orbital parameters and confirmation derive directly from RV fitting and data comparisons

full rationale

The central claim rests on a Keplerian fit to the combined CARMENES VIS/NIR and HIRES RV datasets yielding P = 39.6299 d and M sin i = 6.21 M⊕. Confirmation uses the observed 15-year temporal coherence of the signal and its achromaticity (direct channel comparison), neither of which reduces to a fitted parameter being renamed as a prediction. TESS photometry provides an independent non-detection constraint via BLS and injection-recovery. Stellar luminosity and incident flux for HZ placement follow standard bolometric calculations from literature values. No self-citations, uniqueness theorems, or ansatzes are invoked as load-bearing steps for the detection or characterization. The derivation chain is therefore self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

2 free parameters · 1 axioms · 0 invented entities

The central claim depends on standard assumptions in exoplanet RV detection and the quality of the data reduction from CARMENES and HIRES.

free parameters (2)
  • orbital period
    Fitted from the combined RV time series to derive the reported value and uncertainty.
  • minimum mass
    Derived from the fitted RV semi-amplitude using stellar mass estimate.
axioms (1)
  • domain assumption A temporally coherent and achromatic RV signal distinct from the stellar rotation period is planetary in origin
    Invoked to confirm the signal as planetary rather than activity-induced.

pith-pipeline@v0.9.0 · 5640 in / 1478 out tokens · 106926 ms · 2026-05-13T02:42:48.685161+00:00 · methodology

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Reference graph

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