{"id":"06347596-9ee1-4a35-b8d6-9684dbf39826","arxiv_id":"2506.18550","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":5.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":2,"one_line_summary":"TOI-1846b is a validated transiting super-Earth with radius 1.79 Earth radii on a 3.93-day orbit around a nearby M dwarf, placing it inside the radius valley.","lead":"Astronomers report a validated super-Earth planet, TOI-1846b, about 1.8 times Earth's radius, transiting a nearby small M dwarf star 47 parsecs away. The planet sits inside the sparsely populated radius gap, making it a useful new data point for theories of how small planets form and evolve.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Headline planet radius is tied to an unquoted stellar radius: abstract R* = 0.4115 R_sun and SED R* = 0.397 R_sun give Rp = 1.79 vs 1.86 R_Earth, a ~1-sigma internal inconsistency.","rationale":"Good-faith assessment: the paper is a standard discovery and validation work with strong evidence for a genuine transiting planet: TESS and ground-based multi-band photometry, high-resolution imaging, archival imaging, TRES RVs, FPP about 1e-4 from TRICERATOPS, and no significant TTVs. The transit is detected on target with consistent depths across bands, and the host star is nearby and well-characterized. None of these raise a serious challenge to the planet's existence.\n\nThe most load-bearing concern is the inconsistent stellar radius used to convert the measured transit depth into the headline physical radius. Section 3.1 derives R* = 0.4115±0.0119 R_sun from the Mann et al. (2015) R-M_K relation, and the abstract adopts this value. But EXOFASTv2's SED fit (Table 5) gives R* = 0.397+0.011-0.012 R_sun. The joint-fit planet radius in Table 6 (1.792 R_Earth) is only compatible with the SED radius: Rp/R* = 0.04137 times 0.397 R_sun gives 1.79 R_Earth, while 0.4115 R_sun would give 1.86 R_Earth. This is a 0.065 R_Earth shift, equal to the 1-sigma uncertainty, not a rounding error. It also explains the Teq discrepancy between the abstract and Table 6. Because the paper's title and abstract foreground the 1.79 R_Earth radius and its location in the radius valley, this inconsistency is directly load-bearing: a reader cannot tell which stellar radius is authoritative, and the quoted planet radius inherits that ambiguity.\n\nThe reader's weakest_assumption identified exactly this issue (systematic errors in M-dwarf empirical relations feeding Rp). I agree, and I would sharpen it: the problem is not just external systematic error but an internal inconsistency in the paper's own adopted R*. The validation of the planet itself is independent of this and is solid. The mass is unmeasured (Chen and Kipping inferred), but the paper labels it as 'predicted' and uses it only for interpretive statements (density, TSM, composition); this is a secondary concern. Other internal inconsistencies (systemic RV in Table 4 vs TRES/Gaia; the M_K = 0.408 typo) are real but do not affect the headline radius as directly.\n\nVerdict: the reader's CONDITIONAL verdict is appropriate. The paper requires a consistency pass on the stellar parameters and a single self-consistent set of stellar and planetary values. No change to the verdict is needed from this stress-test.","tokens_in":32070,"tokens_out":12709,"duration_ms":116301,"concrete_test":"Recompute Rp from Table 6's fitted ratio Rp/R* = 0.04137±0.00072 using the stellar radius printed in the abstract, R* = 0.4115±0.0119 R_sun (1 R_sun = 109.076 R_Earth). If the result is 1.86±0.04 R_Earth rather than the reported 1.792+0.065-0.068 R_Earth, the central radius is tied to the SED-based R* = 0.397 R_sun, not the quoted R*, and the paper's headline planet radius is not self-consistently derived.","verdict_should_be":"UNCHANGED","load_bearing_attack":"TOI-1846b's central parameter, the super-Earth radius Rp = 1.792+0.065-0.068 R_Earth (Table 6), is not traced to a single stellar radius. Table 6 gives Rp/R* = 0.04137±0.00072. The abstract and Section 3.1 quote R* = 0.4115±0.0119 R_sun (Mann et al. 2015 R-M_K), while the EXOFASTv2 SED fit (Table 5) gives R* = 0.397+0.011-0.012 R_sun. Recovering the headline 1.79 R_Earth requires the SED radius; using the abstract's 0.4115 R_sun yields about 1.86 R_Earth, a shift of about 0.065 R_Earth, equal to the quoted 1-sigma error. The abstract's equilibrium temperature (589±20 K) likewise comes from the Mann-relation stellar parameters, while Table 6's Teq (568±6 K) comes from the SED radius; both cannot be simultaneously correct. The detection and validation case is strong (FPP about 1e-4, achromatic ground-based transits, high-resolution imaging), so the planet's existence is not in doubt. The load-bearing issue is that the headline radius, and hence the radius-valley placement, is not robust against an internal stellar-parameter inconsistency that should be resolved before the paper is used as a precise reference. Secondary inconsistencies (systemic RV -25.93 vs -20.7 km/s; M_K printed as 0.408 rather than 6.408) reinforce the need for a careful consistency pass.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"This paper reports the discovery and validation of TOI-1846b, a transiting super-Earth-sized planet with period P=3.93067 d around a nearby M dwarf (d≈47 pc). The analysis combines TESS 2-minute photometry from many sectors, ground-based multicolor transit photometry (MuSCAT, MuSCAT2, MuSCAT3, KeplerCam), high-resolution AO/speckle imaging, archival imaging, and TRES/Kast/SpeX spectroscopy. The authors report Rp=1.792+0.065−0.068 R⊕, a mass of 4.4+1.6−1.0 M⊕ predicted from the Chen & Kipping (2017) relation, an equilibrium temperature of 568–589 K depending on the adopted stellar radius, and FPP=(1.17±0.58)×10−4. They place the planet in the radius-valley 'keystone' region and discuss RV and atmospheric follow-up prospects.","tokens_in":32374,"tokens_out":13092,"duration_ms":125801,"significance":"The planet's existence and validation are strongly supported: the transit is detected at high S/N in many TESS sectors, the ground-based light curves are achromatic, high-resolution imaging excludes companions, and TRICERATOPS yields FPP~10−4. The manuscript also includes an independent transit model (TRAFIT), an injection-recovery experiment, and a TTV search, all of which strengthen the discovery. The principal scientific value is the addition of a bright-host (J=10.4) super-Earth in the radius valley around an M dwarf, a target for RV mass measurement and for future radius-valley population studies. The main caveat is that all mass-dependent quantities are inferred from empirical mass-radius relations rather than measured, and the headline radius inherits an unresolved internal inconsistency in the adopted stellar radius.","major_comments":[{"comment":"Table 6 reports Rp/R★=0.04137±0.00072. Combining this ratio with the SED-fit radius R★=0.397+0.011−0.012 R⊙ (Table 5) gives Rp≈1.79 R⊕ as quoted, whereas combining it with the Mann et al. (2015) radius R★=0.4115±0.0119 R⊙ quoted in the abstract and Section 3.1 gives Rp≈1.86 R⊕. The difference is approximately the quoted 1σ uncertainty, yet the text states the two stellar characterizations are 'in excellent agreement' (Section 3.1) and does not specify which stellar radius was adopted in the joint EXOFASTv2 fit. The paper must identify the adopted stellar parameters, propagate them consistently, and reconcile the resulting Rp and Teq values (abstract 589±20 K vs Table 6 568.1±6.1 K) before the radius-valley placement can be considered robust.","section":"Section 5.1 / Table 6 vs Section 3.1 / Abstract"},{"comment":"The mass Mp=4.4+1.6−1.0 M⊕, density ρp=4.20+1.5−0.96 g/cc, surface gravity, RV semi-amplitude K=3.17+1.1−0.73 m/s, and the TSM in Section 6.3 are all outputs of the Chen & Kipping (2017) mass-radius relation rather than measurements. This is acknowledged only in a footnote to Table 6. Statements such as 'It most probably has a water-rich bulk composition based on its radius' (Section 6.1) and the conclusion's 'first guessed to be a water-rich world' treat composition as if it followed from the data when it follows from the adopted prior. I recommend either removing these composition claims or explicitly labeling them as conditional on the Chen & Kipping relation, with the spright posterior (Section 6.2) presented as the only model-agnostic compositional statement.","section":"Section 5.1 / Table 6, Section 6.1"},{"comment":"The systemic radial velocity is internally inconsistent. TRES gives −20.720±0.056 km/s and −20.831±0.034 km/s, Table 4 lists RV=−25.93±2.00 km/s 'This work', Section 2.5 cites a Gaia DR3 RV of '20.64 km/s' without a sign, and Section 3.3 states that the space motion was computed using a 'systemic RV from the SpeX spectrum' whose value is never reported. Because the thin-disk/thick-disk probability and Zmax in Section 3.3 depend directly on the adopted RV, the manuscript should present one adopted systemic RV with its source and propagate that value through the kinematic analysis.","section":"Section 2.3.1 / Table 4 / Section 3.3"}],"minor_comments":[{"comment":"'M_k = 0.408±0.01' is inconsistent with K=9.596 and d=47.244 pc, which give M_K≈6.22; the intended value is presumably 6.4, and this typo should be corrected because it is the input to the Mann et al. (2015) radius relation.","section":"Section 3.1"},{"comment":"The KeplerCam observations are dated 31 Jul 2020 in the table but 'UT2021-05-19' in the text, and the text says both that no transit was detected and that an egress was detected; these statements need to be reconciled.","section":"Section 2.2.1 and Table 2"},{"comment":"'POSSII (1922 and 2011)' is presumably a typo for the POSS-II epoch (1990s) and should be corrected.","section":"Figure 11 caption"},{"comment":"The sentence 'the RV from Gaia DR3 archive is 20.64 km/s' should give the sign explicitly as −20.64 km/s, consistent with the TRES values.","section":"Section 2.5"},{"comment":"Minor language and typographical issues include 'rules out the the possibility' (Section 4.3), 'the the quadratic limb-darkening coefficients' (Section 5.2), and 'the predict RV precision' (Section 6.2).","section":"Throughout"}],"recommendation":"major_revision","confidential_remarks":"The manuscript is publishable after a consistency pass. The main technical concern is the unresolved ~0.015 R⊙ discrepancy between the two stellar radii, which shifts Rp by its own 1σ error and affects the abstract's Teq and the radius-valley claim. I recommend the editor require the authors to rerun or explicitly re-derive the joint fit with a single adopted stellar radius and report all headline numbers from that set. The RV and M_K typos, while not affecting the planet validation, indicate the paper would benefit from careful proofreading."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"The punchline: TOI-1846b looks like a real super-Earth, and the validation work is thorough and standard. But the paper carries two stellar radii that differ at about the 1-sigma level, and the headline planet radius quietly depends on which one you use. That needs to be resolved before anyone cites the radius valley placement.\n\nWhat's new and good: this is the first full validation of TOI-1846.01, using 25 sectors of TESS photometry, ground-based multicolor transits from MuSCAT/MuSCAT2/MuSCAT3 and KeplerCam, high-resolution imaging from Palomar, Shane, SAI, and Gemini, plus TRES RVs. The TRICERATOPS false-positive probability is 1.17e-4, and the achromatic depths and imaging rule out the usual blends. The planet's existence is not in doubt. A 1.8 R_Earth planet on a 3.93-day orbit around a bright (J=10.4) nearby M dwarf is genuinely useful for radius valley statistics and as an RV target. The spright-based K-amplitude forecast is a nice, honest way to advertise follow-up potential.\n\nSoft spots: Section 3 gives R* = 0.4115 from Mann et al., while the EXOFASTv2 SED fit gives R* = 0.397. Table 6's Rp/R* = 0.04137 gives Rp = 1.79 only if you use the SED radius; using the Mann radius gives 1.86 R_Earth, exactly the quoted 1-sigma error. The abstract's Teq = 589 K comes from the Mann parameters, while Table 6 gives 568 K. Also, the systemic RV in Table 4 is -25.93 km/s, while TRES gives -20.7 and Gaia DR3 is quoted as 20.64 km/s in the text; sign conventions aside, those don't agree. And M_K = 0.408 is clearly a typo for ~6.4. None of this threatens the detection, but the published radii and temperatures are not internally consistent. The mass is from Chen & Kipping, so the density, TSM, and water-rich composition talk are model-dependent; the paper does label the mass as predicted, so that's honest, but the discussion leans on it heavily.\n\nBottom line: a competent, standard discovery paper. It deserves peer review, but the authors need to make a consistency pass and report one adopted stellar radius, not two. After that, it's a citeable addition to the small-planet sample.\n\nRecommendation: send to referees, with the request that the consistency issues be addressed.","headline":"A credible, standard validation of a super-Earth whose headline radius depends on which of two inconsistent stellar radii you use; fix that consistency pass and it becomes a useful addition.","tokens_in":33194,"tokens_out":3190,"would_cite":true,"duration_ms":30906,"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":"TOI-1846b is a validated super-Earth with radius 1.79 Earth radii on a 3.9-day orbit around a nearby M dwarf.","keywords":["TOI-1846b","super-Earth","radius valley","M dwarf","transiting planet","planetary validation","TESS","exoplanet formation"],"falsifier":"Measure the star's radius independently (for example, with optical interferometry or asteroseismology) and check whether the planet's radius stays within the roughly 1.5--2 Earth-radius valley; alternatively, a radial-velocity campaign with about 1 m/s precision that fails to detect the predicted 3--5 m/s signal would falsify the planetary interpretation.","tokens_in":31822,"feed_emoji":"🪐","tokens_out":9153,"duration_ms":84240,"temperature":0.7,"pith_summary":"This paper establishes that TOI-1846b, a transiting object detected by TESS around a nearby M dwarf, is a genuine super-Earth rather than an eclipsing binary or background impostor. Joint modeling of space and ground-based photometry yields a radius of $1.79\\pm 0.07$ Earth radii on a 3.93-day orbit, with an inferred mass of about 4.4 Earth masses from an empirical mass-radius relation. The planet sits squarely in the sparsely populated radius valley, the size gap thought to separate rocky super-Earths from gas-rich sub-Neptunes. Because it orbits a bright, nearby M dwarf, TOI-1846b can be followed up with radial-velocity and atmospheric observations that may reveal its bulk composition and test formation models.","feed_headline":"Super-Earth TOI-1846b lands in the M-dwarf radius valley","feed_subtitle":"A 1.79 Earth-radius planet on a 3.9-day orbit is a rare test case for how small planets form and evolve.","key_machinery":"The argument is carried by the radius valley itself as a diagnostic, together with a validation chain that converts a transit signal into a confident planet detection. A precisely measured radius near $1.8\\,R_\\oplus$ for a short-period planet around an M dwarf places it in the 'keystone' region, where competing formation models (photoevaporation, gas-poor formation, gas-depleted formation) predict different compositions. The claim is supported by joint global modeling of the TESS and ground-based multicolor light curves, achromaticity checks across passbands, high-resolution imaging that rules out stellar companions, and a Bayesian false-positive probability calculation.","core_discovery":"The paper's central claim is that TOI-1846b is a validated super-Earth: a planet with $R_p = 1.79\\pm 0.07\\,R_\\oplus$ orbiting the M dwarf TOI-1846 every $3.93067$ days, with an equilibrium temperature near 570--590 K and an estimated mass of $4.4^{+1.6}_{-1.0}\\,M_\\oplus$ inferred from a mass-radius relation. The validation rests on excluding false positives: multicolor ground-based transits confirm the event on the target star and show it is achromatic, high-resolution imaging resolves no stellar companion, and a Bayesian false-positive probability calculation returns $FPP \\approx 1.2\\times 10^{-4}$. With this radius and period, the planet falls in the keystone region of the radius valley where competing formation theories make different predictions, so the paper argues it is a valuable addition to the small sample of such planets needed to discriminate between photoevaporation, gas-poor formation, and gas-depleted formation scenarios.","pith_inferences":["If a high-precision radial-velocity campaign finds a mass near the lower end of the predicted range, the density would place TOI-1846b in the 'water world' regime of the density valley, strengthening the case for a distinct water-rich population around M dwarfs.","The validation template used here (achromatic ground-based transit checks combined with statistical false-positive rejection) could be applied to other single-transit TESS candidates in the radius valley, and the published injection-recovery results calibrate how many such planets may have been missed.","Given the small predicted radial-velocity semi-amplitude of a few meters per second, the paper implicitly prioritizes next-generation stabilized spectrographs; a cheaper near-term test is to re-search the already-collected TESS sectors with a lower detection threshold for additional transits.","A direct test of the radius placement would be to measure the stellar radius independently, since the planetary radius inherits the empirical M-dwarf radius relation; a shift of more than about 5 percent could move the planet out of the valley."],"forward_implications":["A precise mass measurement via radial velocities (expected semi-amplitude of roughly 3--5 m/s) would reveal whether TOI-1846b is rocky, water-rich, or gas-rich, directly testing which formation mechanism operates.","The planet joins the sparse sample of radius-valley planets around bright M dwarfs, helping to refine the valley's location and slope for low-mass stars.","If the composition turns out to be water-rich, the result would support pebble-accretion and water-world interpretations of M-dwarf planets; if rocky, it would favor gas-poor formation scenarios.","The injection-recovery analysis shows that no planets with radii above about 1.5 Earth radii and periods up to 15 days exist in this system, tightening knowledge of its architecture.","Simulated JWST transmission spectra show that water and methane features could be detectable with NIRISS and MIRI if the planet retains an atmosphere, although the transmission spectroscopy metric is modest."],"supporting_citations":[{"why":"Supplies the empirical radius--absolute-magnitude relation used to derive the stellar radius that anchors the planet radius.","marker":"Mann et al. (2015)"},{"why":"Provides the mass-radius relation used to predict the planet's mass and density from its measured radius.","marker":"Chen & Kipping (2017)"},{"why":"Defines the radius valley that the paper uses to interpret the planet's size and orbital placement.","marker":"Fulton et al. 2017"},{"why":"Supplies the model predictions for the radius valley around low-mass stars that define the keystone region in the paper's discussion.","marker":"Cloutier & Menou 2020a"},{"why":"Describes the global fit code used to jointly model the transit light curves and derive the system parameters.","marker":"Eastman et al. (2019)"},{"why":"Provides the statistical validation method used to compute the false-positive probability for the candidate.","marker":"Giacalone et al. (2021)"},{"why":"Offers the density-valley classification and water-world composition guess that the paper applies to TOI-1846b.","marker":"Luque & Pallé (2022)"}],"fun_headline_variants":["Radius valley resident: super-Earth TOI-1846b confirmed","Super-Earth in the valley: TOI-1846b tests planet formation","M-dwarf super-Earth TOI-1846b fills a radius gap","TOI-1846b: a rare super-Earth in the M-dwarf radius valley"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The planetary radius inherits the stellar radius, which comes from empirical M-dwarf relations; if those relations carry a systematic offset for this star, the planet's radius and its claimed position in the radius valley would shift accordingly.","fun_headline_variants_meta":{"raw":{"variants":["Radius valley resident: super-Earth TOI-1846b confirmed","Super-Earth in the valley: TOI-1846b tests planet formation","M-dwarf super-Earth TOI-1846b fills a radius gap","TOI-1846b: a rare super-Earth in the M-dwarf radius valley"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000274,"raw_usage":{"total_tokens":1722,"prompt_tokens":1107,"completion_tokens":615,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":723,"completion_tokens_details":{"reasoning_tokens":527}},"tokens_in":723,"tokens_out":615,"duration_ms":6052,"temperature":1.0,"reasoning_tokens":527,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-15T18:47:06.324296+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Measure the star's radius independently (for example, with optical interferometry or asteroseismology) and check whether the planet's radius stays within the roughly 1.5--2 Earth-radius valley; alternatively, a radial-velocity campaign with about 1 m/s precision that fails to detect the predicted 3--5 m/s signal would falsify the planetary interpretation.","supporting_citations":[],"review_version":2}