{"id":"8add1801-3132-4464-b72d-c73475779eff","arxiv_id":"2412.02069","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":5,"one_line_summary":"This paper confirms and characterizes four transiting giant planets, TOI-6628 b, TOI-3837 b, TOI-5027 b and TOI-2328 b, using TESS and ground-based follow-up.","lead":"Astronomers report four newly confirmed transiting planets around Sun-like stars, including a warm Jupiter in one of the most eccentric orbits known. The finds add rare data points for testing how giant planets form and migrate.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"TOI-6628 b's headline eccentricity of 0.667 rests on a single-planet RV model; the paper's own evidence table does not exclude a circular orbit plus a long-term trend, which could bias e and K.","rationale":"The reader's weakest assumption (blend/dilution) is reasonable but I do not think it is the most load-bearing, because: (i) SPOC centroiding is reported for three targets and is consistent with the target star; (ii) ground-based photometry with small apertures confirms transits on the target for all four systems; (iii) for TOI-3837, the only target with a known close companion, the authors explicitly modeled a blended eclipsing binary and found the planet model strongly favored (χ2 lower by 188). The eccentricity of TOI-6628 b is more central to the paper's scientific value, and the paper itself flags a residual trend. The model comparison in Table 4 does favor the eccentric single-planet model, so this is not a fatal flaw, but the possible presence of an outer companion makes the headline eccentricity less secure than the abstract implies. Hence I partially agree with the reader and keep the CONDITIONAL verdict, with the condition being a two-companion RV fit for TOI-6628.","tokens_in":35767,"tokens_out":1775,"duration_ms":20205,"concrete_test":"Refit the TOI-6628 TESS photometry and all RVs with a two-companion model: one transiting planet (with free e and ω) plus an outer Keplerian, using the same juliet/dynesty priors and settings as Table 6. If the log-evidence of this two-planet model exceeds that of the single eccentric planet by ΔlnZ > 5, and the recovered inner eccentricity drops below 0.5, then the headline eccentricity is not robust and the abstract should be revised.","verdict_should_be":"CONDITIONAL","load_bearing_attack":"The abstract's most notable claim is TOI-6628 b's eccentricity of 0.667 ± 0.016, 'one of the most eccentric orbits of all known warm giants'. This rests on the joint fit of 3 FEROS + 20 HARPS RVs with a single eccentric Keplerian. In Section 4.1 the authors state: 'We observe a trend when fitting a line to the RV residuals of TOI-6628 b, TOI-3837 b and TOI-5027 b, however adding a linear trend to the RV model does not improve the results.' For TOI-6628, Table 4 gives log-evidences of 8658.2 (circular), 8733.7 (eccentric) and 8718.6 (eccentric + trend). So the eccentric model is favored, but the eccentric-plus-trend model is only nominally disfavored (ΔlnZ ≈ 15) while being more complex. More importantly, the existence of a residual trend indicates possible additional structure. A single-planet fit can absorb an outer companion's signal into a biased eccentricity and semi-amplitude: e is known to be degenerate with a linear trend or an outer companion when the RV phase coverage is not perfectly uniform. The HARPS sampling in Table A.1 is dense across several orbital phases, which helps, but the FEROS data are sparse and the trend is acknowledged. If the trend is a real outer companion, the recovered e = 0.667 and K = 78.9 m/s for the inner planet may be systematically shifted. The paper's model comparison only tests a linear trend, not a full two-Keplerian model, and eccentricity uncertainties derived under the single-planet assumption would be underestimated. The dilution fixed to unity is a secondary issue: SPOC centroids, ground-based photometry on the target star, and the dedicated blend modeling for TOI-3837 substantially mitigate the blended-binary scenario. The load-bearing weak point is the uniqueness of the single-eccentric-planet interpretation for TOI-6628 b.","agreement_with_reader":"partial"},"referee_report":{"model":"deepseek-v4-flash","summary":"This manuscript reports the discovery and characterization of four transiting giant planets: TOI-6628 b, TOI-3837 b, TOI-5027 b, and TOI-2328 b. The analysis combines TESS light curves with ground-based photometry from multiple small telescopes and radial velocities from FEROS, HARPS, and PFS, and fits the data with the juliet package under four nested models (no planet, circular single planet, eccentric single planet, eccentric single planet plus linear trend). The paper reports masses, radii, periods, eccentricities, and stellar parameters for all four systems, and interprets the mass-radius constraints with GASTLI and MESA interior models. The headline result is TOI-6628 b: a 0.75 MJ, 0.98 RJ planet on an 18.18 day orbit with eccentricity 0.667 ± 0.016, claimed to be one of the most eccentric warm giants known.","tokens_in":36266,"tokens_out":4765,"duration_ms":51179,"significance":"If the results hold, the paper adds four well-characterized transiting planets in the relatively sparse warm-Jupiter and sub-Saturn regime (P > 10 days), with particular value in the high-eccentricity orbit of TOI-6628 b and the bulk metal fractions derived for all four planets. The work makes good use of independent photometric and spectroscopic datasets: the multi-transit TESS detections are supported by ground-based photometry, the RV signals are coherent with the transit ephemerides, and Bayesian model comparisons are used to discriminate orbital models. The authors are also appropriately transparent about limitations: they state that the eccentricity of TOI-3837 b is not strongly preferred over a circular orbit, they note linear trends in RV residuals for three systems, and they flag the Teq = 1000 K approximation used for the two hottest planets in the interior modeling. These explicit caveats are a strength of the paper. The main risks lie in the fixed dilution factors for two targets without high-resolution imaging and in the single-Keplerian interpretation of the TOI-6628 b eccentricity.","major_comments":[{"comment":"The dilution factor md is fixed to 1.0 for every photometric dataset in Tables 6-9, but high-resolution imaging is presented only for TOI-3837 and TOI-5027 (Section 2.6). For TOI-6628, a 14.13 mag star lies near the TESS aperture (Section 2.1), and for TOI-2328 no high-resolution imaging is reported. An unresolved or partially resolved companion could dilute the transit signal and bias the inferred radii and densities, which are central to the reported bulk properties. The authors should either obtain or analyze high-angular-resolution imaging for TOI-6628 and TOI-2328, or quantitatively bound the dilution using the available Gaia and ground-based photometry and propagate that uncertainty into Rp and ρp.","section":"Section 2.1; Tables 6-9"},{"comment":"The headline eccentricity e = 0.667 ± 0.016 for TOI-6628 b is derived from a single-planet eccentric Keplerian model. The paper states in Section 6 that linear trends in the RV residuals of TOI-6628 b suggest possible outer companions, and Table 4 shows that only a linear-trend model was tested, not a two-Keplerian model. Because an outer companion can be partially absorbed into a biased eccentricity and semi-amplitude for the inner planet, the authors should fit a two-Keplerian model (or provide a residual-periodogram and injection-recovery check) to demonstrate that e and K are not significantly shifted. The current evidence against the circular model is strong, but the robustness of the single-planet eccentric parameters to an additional companion is not established.","section":"Section 4.1.1; Table 4"},{"comment":"The statement that the interior models provide 'supporting evidence to the core accretion theory of planet formation' is stronger than the analysis supports. The GASTLI and MESA models assume a two-layer structure with a rock/water core and a H/He envelope, and the free CMF and envelope metallicity are fitted to the observed mass and radius; no alternative interior structures (e.g., metal-rich envelope without a distinct core, or a fully mixed interior) are tested. The Teq = 1000 K approximation for TOI-3837 b and TOI-5027 b is acknowledged, but the quoted ΔCMF = 0.02 for TOI-3837 b is a point estimate and is not propagated into the Table 5 uncertainties. I recommend softening the core-accretion conclusion or adding a comparison against alternative interior models.","section":"Section 5; Section 7"},{"comment":"For TOI-3837 b the Δlog-evidence between the eccentric and circular models is less than 5, and the paper correctly reports this. However, the discussion in Section 6 and the Conclusions list TOI-3837 b alongside the securely eccentric planets without restating this caveat. The text should carry the circular-orbit possibility through to the abstract and conclusions, or at least to the discussion, so that readers do not over-interpret e = 0.198 for this planet.","section":"Section 4.1; Table 4"}],"minor_comments":[{"comment":"There are multiple typos and grammatical slips: 'consistsent' appears in the abstract and elsewhere, 'consistss' appears in Section 2.2.2, and several sentences use singular/plural agreement incorrectly (e.g., 'Table 2.1 show'). A careful proofreading pass is needed.","section":"Abstract; throughout"},{"comment":"The left panel caption refers to 'TOI-6028 b'; this should be 'TOI-6628 b'.","section":"Figure 12 caption"},{"comment":"The reference 'see Table 2.2.2' for the planet mass prior should be Table 3; the current reference is nonsensical.","section":"Section 5"},{"comment":"Several activity-index entries appear implausibly large, for example HeI values of -18.728, -24.954, and -10.363 in Table A.1. The authors should check for unit errors or flag these as upper limits/excluded values.","section":"Tables A.1-A.4"},{"comment":"The sentence 'We observe a peak at the period of the RVs GLS peak' is confusing; it should be clarified that TOI-6628 shows an RV peak at the photometric period but below the 1% FAP threshold.","section":"Section 4; Figure 3"},{"comment":"The phrase 'the top second panel from left to right' is awkward; it should say 'the second panel from the left in the top row' or similar.","section":"Section 2.2.2"}],"recommendation":"major_revision","confidential_remarks":"The paper is within the scope of A&A and the discovery claims are well supported by independent photometry and RVs. My main concern is not the basic detections but the robustness of two headline numbers: the TOI-6628 b eccentricity under an unmodeled outer companion, and the radii/densities under the fixed-dilution assumption for the two targets without high-resolution imaging. Both are fixable with additional analysis or appropriately softened claims, so I recommend major revision rather than rejection. The interior-structure interpretation should also be worded more carefully to avoid the appearance of circularity."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"The one thing to know: this is a solid, workmanlike discovery paper adding four warm giant planets (one sub-Saturn), with TOI-6628 b as the standout because of its e = 0.667. The eccentricity is not just a fit artifact: the Bayesian evidence strongly prefers the eccentric single-planet model over a circular orbit (Delta lnZ ~ 75). So the headline claim is robust against a circular-orbit alternative.\n\nWhat I liked: the joint photometric+RV modeling is thorough, with model comparison across four scenarios. The blend analysis for TOI-3837 is a genuine effort, including physical association checks, and the high-resolution imaging for two targets is a plus. The interior modeling with two independent codes (GASTLI and MESA) is a nice cross-check, even if it rests on standard assumptions. Tables of RVs in the appendix make the data usable.\n\nSoft spots: (1) The abstract reports e = 0.198 for TOI-3837 b as a measurement, but the paper's own evidence table gives Delta lnZ < 5 between circular and eccentric; that should be flagged in the abstract. (2) The number of FEROS RVs for TOI-5027 is inconsistent: Section 2.5.1 says 23, Section 4.1.3 says 16. (3) The claim that the interior models 'provide evidence supporting the core accretion model' is overreach - the models assume a core+envelope structure and then find it fits; that is interpretation, not independent evidence. (4) Ground-based light curves are not released, which limits reproducibility. (5) For TOI-6628 b, the paper does not test a two-Keplerian model; an outer companion could bias e. The single-Keplerian evidence is strong, but a future paper with more RVs could revise e. That is a caveat, not a fatal flaw.\n\nThe reader's worry about dilution is mostly answered by the ground-based photometry and the TOI-3837 blend modeling; the fixed dilution factors are justified for these targets, though I would like to see high-resolution imaging for TOI-2328.\n\nBottom line: this is a useful contribution to the warm-Jupiter census. The inconsistencies are minor and fixable. I would send it to a good referee and ask for a round of minor revisions. Worth citing once published.","headline":"Four well-characterized warm giants, including a high-eccentricity outlier whose headline eccentricity is robust against a circular orbit but untested against a distant companion.","tokens_in":36953,"tokens_out":3916,"would_cite":true,"duration_ms":37785,"reading_group":"maybe","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 four transiting giant planets and reports that TOI-6628 b has one of the most eccentric orbits known among warm Jupiters.","keywords":["warm Jupiter","transiting exoplanet","radial velocity","eccentric orbit","TESS","planetary interiors","core accretion","sub-Saturn"],"falsifier":"Take high-resolution imaging of TOI-6628, TOI-5027, and TOI-2328 at sub-arcsecond resolution and a contrast of a few magnitudes; detection of a blended companion within the TESS aperture would change the required dilution, and re-fitting the transits with free dilution would shift the quoted radii. For TOI-3837 b, additional radial velocities that push the eccentric-orbit model's log-evidence above 5 relative to a circular orbit would confirm its measured eccentricity.","tokens_in":35602,"feed_emoji":"🪐","tokens_out":6467,"duration_ms":54695,"temperature":0.7,"pith_summary":"This paper reports the confirmation and characterization of four transiting giant planets discovered in TESS light curves, with follow-up from ground-based photometry and radial velocities. The headline result is TOI-6628 b, a 0.75-Jupiter-mass planet with radius 0.98 Jupiter radii on an 18.18-day orbit with eccentricity 0.667, placing it among the most eccentric warm giants known. The other three planets are TOI-3837 b (0.59 MJ, e=0.198), TOI-5027 b (2.01 MJ, e=0.395), and TOI-2328 b (0.16 MJ, e=0.057), all with periods above 10 days. The authors argue that interior models of all four planets favor a rocky-icy core with a H/He envelope, supporting core-accretion formation for this population.","feed_headline":"Four warm giant planets confirmed, one highly eccentric","feed_subtitle":"TESS transits and ground-based radial velocities pin down masses, radii, and eccentric orbits.","key_machinery":"The argument is carried by a joint Bayesian fit (the juliet package) of TESS and ground-based transit light curves together with radial-velocity time series, using an eccentric Keplerian orbit, quadratic limb darkening, and per-instrument offsets and jitter; periodicity is first found with BLS and GLS periodograms. Planet radii and masses come from the combined photometric depth and RV semi-amplitude, and compositions are derived by comparing measured masses, radii, and ages to the GASTLI and MESA interior models, both assuming a rocky-icy core and H/He envelope.","core_discovery":"The authors establish that TOI-6628 b, TOI-3837 b, TOI-5027 b, and TOI-2328 b are genuine transiting planets rather than false positives from blended binaries or stellar activity. Combining TESS photometry with ground-based transit light curves and radial velocities from FEROS, HARPS, and PFS, they derive self-consistent orbital solutions: TOI-6628 b has mass 0.75±0.06 MJ, radius 0.98±0.05 RJ, period 18.18424 days, and eccentricity 0.667±0.016; TOI-3837 b has mass 0.59±0.06 MJ, period 11.88865 days, eccentricity 0.198; TOI-5027 b is the most massive at 2.01±0.13 MJ with period 10.24368 days and eccentricity 0.395; TOI-2328 b is a sub-Saturn at 0.16±0.02 MJ with period 17.10197 days and near-circular orbit. For TOI-3837 b, a dedicated blend analysis rejects a stellar eclipsing binary explanation. Interior structure models then yield bulk metal mass fractions, with the four planets showing a rocky-icy core plus H/He envelope and metal enrichment consistent with core accretion.","pith_inferences":["If TOI-6628 b's high eccentricity is robust, the most likely formation path involves planet–planet scattering or secular perturbations that first excited the orbit, with the current 18-day period requiring that tidal circularization has not yet completed; a search for outer companions in the reported linear RV trends would test this.","High-resolution imaging of TOI-6628 and TOI-2328 at sub-arcsecond scales could reveal companions that would dilute the transit depth; without it, the fractional radius and derived density carry an unquantified systematic risk.","The reported eccentricity of TOI-3837 b rests on a log-evidence difference below 5 relative to a circular orbit, so the eccentricity should be treated as tentative until more radial velocities arrive."],"forward_implications":["TOI-6628 b adds a 0.67-eccentricity warm giant to a population where only about 5% of known giants have e>0.5, sharpening tests of high-eccentricity migration.","The three eccentric systems (TOI-6628 b, TOI-3837 b, TOI-5027 b) occupy a sparse region of the period–eccentricity plane, providing evidence that warm giants retain a wider eccentricity distribution than hot Jupiters.","Interior retrievals put the four planets on the mass–bulk metallicity trend defined by other warm giants, with TOI-5027 b slightly metal-rich, a composition pattern expected if core accretion proceeds with pebble and vapour-enriched gas.","Predicted Rossiter–McLaughlin amplitudes of 23–54 m/s make these systems promising targets for measuring spin–orbit obliquity, which can discriminate migration channels."],"supporting_citations":[{"why":"Supplies the TESS mission and light curves that define the four transiting candidates.","marker":"Ricker et al. (2015)"},{"why":"Provides the juliet joint transit and radial-velocity modeling used for all orbital fits.","marker":"Espinoza et al. (2019)"},{"why":"Supplies the BLS periodogram used to identify transit periods in the photometry.","marker":"Kovács et al. (2002)"},{"why":"Supplies the GLS periodogram used to search for periodicities in the radial velocities.","marker":"Zechmeister & Kürster (2018)"},{"why":"Provides astrometry and photometry that anchor the stellar parameter derivation.","marker":"Gaia Collaboration et al. (2018)"},{"why":"Supplies the ceres pipeline that reduces the spectra and produces the radial velocities and activity indices.","marker":"Brahm et al. (2017)"},{"why":"Provides the blended eclipsing binary model used to reject a false-positive interpretation for TOI-3837 b.","marker":"Hartman et al. (2019)"},{"why":"Supplies the mass–bulk metallicity trend used to interpret the planets' core-accretion formation.","marker":"Thorngren et al. (2016)"},{"why":"Supplies the GASTLI interior structure models used to infer core mass fractions and envelope metallicities.","marker":"Acuña et al. (2024, 2021)"},{"why":"Supplies the MESA-based interior modeling implementation used for comparison in the age-radius diagram.","marker":"Jones et al. (2024)"}],"fun_headline_variants":["TESS confirms four new giant planets, one highly eccentric","Highly eccentric warm Jupiter tops new four-planet haul","Three warm Jupiters and a sub-Saturn: TESS's latest four","Warm Jupiter with extreme orbit highlights four new TESS finds","Four new giant exoplanets confirmed, one with high eccentricity"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The transit signals are assumed to come from the target stars alone: photometric dilution is fixed to unity for every dataset except the explicit blend modeling of TOI-3837 b, so an unresolved companion or blended eclipsing binary on the other three targets would change the inferred radii, masses, and eccentricities.","fun_headline_variants_meta":{"raw":{"variants":["TESS confirms four new giant planets, one highly eccentric","Highly eccentric warm Jupiter tops new four-planet haul","Three warm Jupiters and a sub-Saturn: TESS's latest four","Warm Jupiter with extreme orbit highlights four new TESS finds","Four new giant exoplanets confirmed, one with high eccentricity"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.001129,"raw_usage":{"total_tokens":4906,"prompt_tokens":1369,"completion_tokens":3537,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":985,"completion_tokens_details":{"reasoning_tokens":3448}},"tokens_in":985,"tokens_out":3537,"duration_ms":25677,"temperature":1.0,"reasoning_tokens":3448,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-11T23:52:18.099329+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Take high-resolution imaging of TOI-6628, TOI-5027, and TOI-2328 at sub-arcsecond resolution and a contrast of a few magnitudes; detection of a blended companion within the TESS aperture would change the required dilution, and re-fitting the transits with free dilution would shift the quoted radii. For TOI-3837 b, additional radial velocities that push the eccentric-orbit model's log-evidence above 5 relative to a circular orbit would confirm its measured eccentricity.","supporting_citations":[],"review_version":1}