{"id":"31dc34c2-756d-44d0-9415-61eff0fd1eeb","arxiv_id":"2502.07086","paper_version":2,"verdict":"CONDITIONAL","confidence":"HIGH","novelty_score":4.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":3,"one_line_summary":"A multi-wavelength radial velocity analysis confirms the 9.55-day planet around Gl 480, finds a prior-dependent tentative 6.4-day signal, and places upper limits on planets around Gl 382.","lead":"Using near-infrared and optical radial velocity data, the authors confirm the 9.55-day planet around the M dwarf Gl 480 and refine its minimum mass to about 8.8 Earth masses, while finding no planets around Gl 382. The study also reports a tentative 6.4-day signal around Gl 480 that needs more data and shows how much activity modeling choices can change detections.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"The 9.5 d planet period is robust, but the quoted mass 8.8±0.7 M⊕ rests on a common-K joint fit over a ~2σ nIR/optical K discrepancy that is never tested; a separate-K model could shift the mass outside the quoted error.","rationale":"The paper's strongest claim—confirmed 9.5 d planet with M sin i=8.8±0.7 M⊕—is supported by the signal's presence in independent nIR and optical datasets, which is real evidence. However, the load-bearing condition for the mass value is that a single Keplerian amplitude K describes all instruments. Table 3 shows SPIRou alone gives K=3.6±0.5 m/s and HARPS+CARMENES alone give 5.0±0.5 m/s. The joint value 4.5±0.3 lies between, but the tension is ~2σ, not 'within 5σ' as the text loosely states in Sec. 3.1.3. The paper does not report whether the joint fit prefers separate per-instrument amplitudes, nor does it show the joint K_b without Wapiti/GP or with the alternative prior sets. Since the mass estimate is the novelty (8.8 vs Feng's 13.2 M⊕), a systematic bias in K of 0.7 m/s would shift the mass by ~1.4 M⊕, i.e., outside the quoted errors. This does not threaten the planet's existence—the period and phase are consistent across datasets—but it means the 'improved mass' is conditional on the common-K modeling assumption. The 6.4 d tentative signal is properly caveated, but the mass claim in the abstract is not. The concrete test above would settle whether the discrepancy is real or a modeling artifact. If separate K is not preferred and K is stable under prior variations, the mass claim holds; otherwise the mass should be quoted with a larger uncertainty or as a range. The reader's own weakest_assumption concerned the prior dependence of the 6.4 d signal; while related to activity modeling, that is a different load-bearing point, hence partial agreement.","tokens_in":24618,"tokens_out":10861,"duration_ms":97636,"concrete_test":"Recompute the joint Gl 480 fit with a model that allows separate K_b per instrument (SPIRou, HARPS, CARMENES) using the same Wapiti and GP setup as the final model, and compute the Bayesian evidence versus the common-K model. Then rerun the common-K model with the 6.4 d signal excluded and with GP Priors I and II instead of the adopted dLW-based Priors III. If the separate-K model is preferred by log BF > 1, or if K_b (and hence M sin i) shifts by more than ~1σ across the prior/exclusion variations, the quoted 8.8±0.7 M⊕ is not robust and the abstract's mass claim should be softened to a range or to the value from the most conservative model.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The central claim (Gl 480 b, P=9.5537±0.0005 d, M sin i=8.8±0.7 M⊕) is supported by the 9.5 d signal being present in both SPIRou and optical data, but the quoted mass rests on a joint fit that assumes a common semi-amplitude K_b across instruments. Table 3 gives K_b=3.6±0.5 m/s for SPIRou alone and 5.0±0.5 m/s for HARPS+CARMENES alone; the joint value is 4.5±0.3 m/s. This ~2σ tension is acknowledged in Sec. 3.1.3 but never tested. The paper verifies only that Wapiti/GP corrections do not explain the low SPIRou amplitude (no-correction SPIRou K=3.8±0.7), and does not report K_b for the joint fit without Wapiti/GP, without the 6.4 d signal, or under Priors I/II instead of the adopted dLW-based Priors III. Since the new mass is 2.4σ below Feng et al. (2020)'s 13.2±1.7 M⊕, the 'improved mass' claim is only as secure as the common-K assumption. If the optical GP or the joint GP partially absorbs the 9.5 d signal, or if a wavelength-dependent activity term at ~9.5 d is present in SPIRou, M sin i could be biased by more than 1σ.","agreement_with_reader":"partial"},"referee_report":{"model":"deepseek-v4-flash","summary":"This paper presents a radial-velocity (RV) analysis of two nearby M dwarfs, Gl 480 and Gl 382, combining near-infrared SPIRou data with optical HARPS and CARMENES data. The authors use the LBL framework, the Wapiti systematics-correction method, Bayesian periodograms, and quasi-periodic Gaussian-process models with several choices of priors. For Gl 480, they confirm the previously reported 9.5537 d planet and derive a joint-fit minimum mass of 8.8 +/- 0.7 Earth masses, significantly lower than the Feng et al. (2020) value of 13.2 +/- 1.7 Earth masses. They also report a tentative 6.4 d signal whose significance depends strongly on the GP prior choice. For Gl 382, no planetary signals are found, and they place an upper limit of about 5.9 Earth masses for companions in the habitable zone.","tokens_in":25017,"tokens_out":4878,"duration_ms":45006,"significance":"If the main result holds, the paper provides a useful multi-wavelength confirmation and an improved mass measurement for a known super-Earth around an M dwarf, and it demonstrates a careful systematics-correction pipeline for SPIRou data. The explicit injection-recovery test for the optical non-detection of the 6.4 d signal and the transparent reporting of prior sensitivity are commendable. The Gl 382 non-detection and detection-limit analysis are also valuable for the SLS planet-search program. However, the central mass claim rests on a common-semi-amplitude assumption that is not tested, and the tentative 6.4 d candidate is only significant under one set of activity-informed priors. These issues do not undermine the existence of the 9.5 d signal, but they do affect the headline mass and the status of the second signal.","major_comments":[{"comment":"The headline mass M sin i = 8.8 +/- 0.7 Earth masses rests on the joint fit with a common semi-amplitude K_b = 4.5 +/- 0.3 m/s, while the SPIRou-only and optical-only fits give K_b = 3.6 +/- 0.5 and 5.0 +/- 0.5 m/s, a difference of about 2 sigma given the quoted uncertainties. The statement in §3.1.3 that the difference is 'within 5 sigma' is not a quantitative compatibility test, and the paper never fits a model with separate K_b for the nIR and optical data. Because the claimed improvement over Feng et al. (2020) depends on this joint value, the authors should either report a separate-K fit with its BIC and parameters, or otherwise demonstrate that the common-K assumption does not bias the period and mass.","section":"§3.1.4, Table 3"},{"comment":"The 6.4 d signal is only significant when the SPIRou GP uses Priors III, whose hyperparameters are derived from the dLW activity time series of the same star. In the SPIRou-only analysis the log BF is 2.31, 1.90, and 3.71 for Priors I, II, and III, all below the adopted threshold of 5; in the combined fit the signal reaches log BF = 6.7 only with Priors III, while remaining below threshold with Priors I and II. Because the prior set was chosen partly on the basis of BIC for the same dataset that contains the candidate, the reported significance is not robust. The manuscript should present the 6.4 d significance and parameters for all prior sets in the main text and should clearly label Gl 480 c as a prior-dependent candidate rather than listing it as a planet in the final parameter table.","section":"§3.1.2, §3.1.4, Table 3"},{"comment":"The removal of four outliers from the Gl 480 SPIRou dataset is described without any objective rejection criterion. Since the 9.5 d semi-amplitude is only about 3.6 m/s, a handful of points can influence the fitted K and thus the derived planet mass. Please state the outlier criterion (for example, a residual threshold, a bad-pixel flag, or an instrumental issue) and show that the main results are unchanged when the outliers are retained.","section":"§2.4"}],"minor_comments":[{"comment":"The table caption says 'Gl 480' but the table contains parameters for Gl 382; the caption should be corrected.","section":"Table 5"},{"comment":"The conclusion contains a duplicated phrase: 'to better constrain its orbital parameters., this signal could not be detected with these data.' The second clause appears to be a copy-paste error and should be removed.","section":"Section 4"},{"comment":"There are several typographical errors: 'Eath' should be 'Earth', 'rotatinoal' should be 'rotational', 'twp panels' should be 'two panels', and 'acknoweldge' should be 'acknowledge'.","section":"§2.2, §3.2.1, Figure 8, Acknowledgements"},{"comment":"The phrase 'within 5 sigma' for the nIR/optical semi-amplitude difference is misleading; with the quoted errors the difference is approximately 2 sigma. Please quantify the compatibility properly or reword.","section":"§3.1.3"},{"comment":"The caption refers to 'planets 1 and 2', but the 6.4 d signal is described elsewhere as tentative; using 'signals' or 'candidate' would be more consistent with the paper's own caveats.","section":"Figure 5 caption"},{"comment":"The statement that the individual datasets 'do not overlap' is ambiguous; the authors likely mean that the time baselines of the optical datasets do not overlap with the long SPIRou baseline or that the observations are not simultaneous. Please clarify.","section":"§3.1.4"}],"recommendation":"major_revision","confidential_remarks":"The manuscript fits the scope of A&A and I see no concerns about attribution or novelty beyond the technical issues described above. The main result is plausible but the mass claim needs a separate-K test, and the tentative 6.4 d candidate should be presented with its full prior dependence before publication."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"First thing you should know: this is a solid survey paper. It confirms the known 9.55 d planet around Gl 480 with better precision, adds a clearly labeled tentative 6.4 d candidate that probably is not real yet, and delivers a useful null result with a habitable-zone mass upper limit for Gl 382. The headline mass of 8.8±0.7 M⊕ is an improvement over Feng et al.'s 13.2±1.7 M⊕, but it rests on a joint fit that assumes the same semi-amplitude in the near-infrared and optical. The two datasets individually disagree at roughly 2σ: K=3.6±0.5 m/s from SPIRou, K=5.0±0.5 m/s from HARPS+CARMENES. The paper acknowledges this discrepancy but never tests a separate-K model. That is the main soft spot. If the SPIRou amplitude is suppressed by activity or systematics, the joint mass could shift outside the quoted error.\n\nWhat is genuinely good: the multi-wavelength approach is thoughtful, the Wapiti correction is described in enough detail, the activity-indicator analysis is thorough, and the injection-recovery test for the 6.4 d signal is exactly the right way to check an optical non-detection. The 9.5 d signal is secure—it is present in SPIRou alone, in the optical alone, and was already known. The Gl 382 upper limit is clean and useful.\n\nThe 6.4 d candidate is handled honestly but it is fragile. It only passes the log BF=5 threshold with one of three GP prior sets (the dLW-based Priors III), and even then the final model includes it partly for consistency with their detection criterion. That is defensible, but it should be presented more clearly as a candidate, not a detection. Also, four outliers are removed from Gl 480 without a stated objective criterion; that should be quantified. The assumption that Wapiti components do not absorb planetary signal is worth testing, though they do at least check the no-correction case for the 9.5 d amplitude.\n\nCitation pattern looks fine; Feng et al. is properly credited and the discrepancy with it is discussed. The paper is not overselling: the abstract explicitly calls the 6.4 d signal tentative.\n\nWho is this for? RV practitioners working on M dwarfs and anyone compiling planet catalogs. It is a useful data point, not a breakthrough, but it deserves a serious referee. I would send it to review with a request for a separate-K fit and a more rigorous treatment of the outliers.","headline":"Solid survey paper that confirms a known 9.55 d planet with an improved—but possibly prior-dependent—mass, adds a fragile 6.4 d candidate, and gives a clean null result for Gl 382; the main soft spot is the untested common-K assumption across nIR/optical data.","tokens_in":25632,"tokens_out":1692,"would_cite":true,"duration_ms":15335,"reading_group":"yes","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"deepseek-v4-flash","headline":"This paper confirms the 9.55-day super-Earth around Gl 480 by combining near-infrared and optical radial velocities, and finds that a tentative 6.4-day signal depends on how stellar activity is modeled.","keywords":["radial velocities","M dwarf planets","SPIRou","near-infrared spectroscopy","Gaussian process regression","stellar activity","Gl 480","Gl 382"],"falsifier":"A stacked periodogram of new high-cadence radial velocities of Gl 480 at 6.4 days would settle the candidate: if the signal is a planet, its log Bayes factor should rise steadily above 5 as observations accumulate, while an activity artifact would fluctuate or fade when the Gaussian-process priors are changed.","tokens_in":24433,"feed_emoji":"🪐","tokens_out":8731,"duration_ms":70886,"temperature":0.7,"pith_summary":"This paper tests whether two nearby M dwarfs host planets by combining near-infrared radial velocities from the SPIRou spectrograph with published optical velocities from HARPS and CARMENES. It confirms that Gl 480 hosts a super-Earth on a 9.5537-day orbit and revises its minimum mass down to 8.8 Earth masses, a value meaningfully different from the earlier 13.2 Earth masses. The same analysis uncovers a tentative 6.4-day signal that only crosses the detection threshold when stellar activity is modeled with priors taken from one activity indicator, so the paper treats it as unconfirmed. For Gl 382, no planet survives activity correction, and the dataset sets an upper mass limit of about 5.9 Earth masses for any companion in the habitable zone.","feed_headline":"SPIRou data confirm a 9.55-day super-Earth around Gl 480","feed_subtitle":"NIR and optical RVs together set the planet's minimum mass at 8.8 Earth masses.","key_machinery":"The argument is carried by three components working in series: the line-by-line (LBL) extraction that turns SPIRou spectra into per-line radial velocities; the Wapiti method, a weighted principal-component analysis applied to those per-line time series to identify and subtract instrumental systematics; and quasi-periodic Gaussian-process regression on the radial-velocity time series to absorb stellar activity. The Gaussian process is the load-bearing piece for the weak signals, because its rotation period and smoothing hyperparameters are set from stellar activity indicators, and changing those priors changes whether the 6.4-day signal is detected.","core_discovery":"The paper's central claim is that a joint analysis of SPIRou near-infrared and HARPS/CARMENES optical radial velocities, cleaned of instrumental systematics by the Wapiti weighted-principal-component correction and of stellar activity by quasi-periodic Gaussian processes, confirms one planet around Gl 480: period $9.5537 \\pm 0.0005$ d, semi-amplitude $K = 4.5 \\pm 0.3$ m s$^{-1}$, and minimum mass $8.8 \\pm 0.7$ M$_\\oplus$. It also reports that the previously claimed mass of $13.2 \\pm 1.7$ M$_\\oplus$ is not reproduced, and that a low-amplitude signal at $6.4$ d is present but not robust: its log Bayes factor rises above 5 only when the Gaussian-process priors come from the dLW activity indicator, and the signal is compatible with nondetection in the optical data. For Gl 382, the authors find that all radial-velocity variation is explained by stellar activity, and injection-recovery tests set an upper limit of $5.9 \\pm 0.8$ M$_\\oplus$ on a habitable-zone companion.","pith_inferences":["Editorial inference: the prior-dependence of the 6.4-day signal suggests that many ultra-low-amplitude M-dwarf radial-velocity candidates may be similarly fragile, and reporting the full prior-sensitivity range is the right default for such claims.","Editorial inference: if the 6.4-day signal is real, the near 3:2 resonance with the 9.55-day planet would make Gl 480 a natural target for transit-timing searches if a transiting geometry is ever found.","Editorial inference: the 50-day signal seen in Gl 382's near-infrared and HARPS activity indicators but not in optical radial-velocity residuals hints that wavelength-dependent surface features affect radial velocities differently; a testable extension would be to model simultaneous optical and near-infrared epochs with the multi-dimensional Gaussian-process approach the paper names as future work"],"forward_implications":["If the 9.5537-day planet is real, Gl 480 b has a minimum mass near 8.8 Earth masses, placing it in the super-Earth regime with a likely equilibrium temperature around 406 K.","The revised mass is about 30 percent lower than the earlier HARPS/HIRES estimate, which would change any conclusions about the planet's bulk composition drawn from the older value.","If the tentative 6.4-day signal is confirmed by more data, the two periods lie close to a 3:2 commensurability, making the system interesting for orbital dynamics.","For Gl 382, the absence of signals above the injection-recovery threshold implies that any habitable-zone companion has minimum mass below about 5.9 Earth masses.","The paper's demonstration that activity priors decide the 6.4-day detection means future low-amplitude claims should report sensitivity to activity modeling choices."],"supporting_citations":[{"why":"Supplies the line-by-line radial-velocity extraction method used on SPIRou spectra.","marker":"Artigau et al. (2022)"},{"why":"Supplies the Wapiti weighted principal-component correction that removes instrumental systematics.","marker":"Ould-Elhkim et al. (2023)"},{"why":"Describes the SPIRou spectropolarimeter and its data products.","marker":"Donati et al. (2020)"},{"why":"Provides the Bayesian periodogram and the log-Bayes-factor significance threshold used to search for signals.","marker":"Delisle et al. (2018)"},{"why":"Provides the non-informative Gaussian-process priors used as the baseline activity model.","marker":"Camacho et al. (2023)"},{"why":"Reported the original 9.567-day planet detection around Gl 480 that this paper refines and tests.","marker":"Feng et al. (2020)"},{"why":"Supplies the HARPS optical radial-velocity time series used in the joint fit.","marker":"Trifonov et al. (2020)"},{"why":"Supplies the CARMENES optical radial-velocity time series used in the joint fit.","marker":"Ribas et al. (2023)"},{"why":"Provides stellar masses and radii used to convert radial-velocity amplitude to minimum planet mass.","marker":"Cristofari et al. (2022)"}],"fun_headline_variants":["Gl 480's 9.55-day super-Earth confirmed at 8.8 Earth masses","Multi-telescope RVs confirm super-Earth around Gl 480","Gl 382: no planets, just stellar activity","SPIRou + HARPS + CARMENES: one planet, one activity-only star","New RV analysis finds super-Earth at 9.55 days, rejects larger mass"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The load-bearing premise is that the quasi-periodic Gaussian-process model with priors taken from the dLW activity indicator correctly separates stellar activity from the 6.4-day signal; if those priors misrepresent the star, that candidate disappears, though the 9.55-day planet would remain.","fun_headline_variants_meta":{"raw":{"variants":["Gl 480's 9.55-day super-Earth confirmed at 8.8 Earth masses","Multi-telescope RVs confirm super-Earth around Gl 480","Gl 382: no planets, just stellar activity","SPIRou + HARPS + CARMENES: one planet, one activity-only star","New RV analysis finds super-Earth at 9.55 days, rejects larger mass"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000986,"raw_usage":{"total_tokens":4299,"prompt_tokens":1180,"completion_tokens":3119,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":796,"completion_tokens_details":{"reasoning_tokens":3028}},"tokens_in":796,"tokens_out":3119,"duration_ms":19755,"temperature":1.0,"reasoning_tokens":3028,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-08T13:50:43.608183+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"A stacked periodogram of new high-cadence radial velocities of Gl 480 at 6.4 days would settle the candidate: if the signal is a planet, its log Bayes factor should rise steadily above 5 as observations accumulate, while an activity artifact would fluctuate or fade when the Gaussian-process priors are changed.","supporting_citations":[{"cited_title":"B., S \\'e gransan , D., Dumusque , X., et al","cited_arxiv_id":null,"evidence_quote":"Provides the Bayesian periodogram and the log-Bayes-factor significance threshold used to search for signals."},{"cited_title":"D., Faria , J","cited_arxiv_id":null,"evidence_quote":"Provides the non-informative Gaussian-process priors used as the baseline activity model."},{"cited_title":"A., Clement , M","cited_arxiv_id":null,"evidence_quote":"Reported the original 9.567-day planet detection around Gl 480 that this paper refines and tests."},{"cited_title":"2023, Astronomy and Astrophysics, 670, A139","cited_arxiv_id":null,"evidence_quote":"Supplies the CARMENES optical radial-velocity time series used in the joint fit."},{"cited_title":"I., Donati , J","cited_arxiv_id":null,"evidence_quote":"Provides stellar masses and radii used to convert radial-velocity amplitude to minimum planet mass."}],"review_version":1}