{"id":"1d6de5e4-e640-4123-a51d-7dfe3e199e5d","arxiv_id":"2505.02908","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":5.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":6,"one_line_summary":"Early shock-cooling observations of Type IIb SN 2024uwq reveal a partially stripped blue or yellow supergiant progenitor with a radius of 14.6-57.1 solar radii and an envelope mass of 0.7-1.35 solar masses.","lead":"Astronomers caught the Type IIb supernova SN 2024uwq early, recording its double-peaked light curve and the brief shock-cooling flash from the exploding star's outer envelope. The observations point to a partially stripped blue or yellow supergiant progenitor, a transitional case that helps map how binary stars shape supernova diversity.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Radius constraint is model-dependent with factor~4 spread; the quoted 14.6-57.1 R_sun range is the union of posteriors, not a single robust measurement.","rationale":"The reader's first-identified weak point is exactly the model dependence of the radius inference plus the poorly constrained rise and the ambiguity in explosion epoch. Reading the paper in good faith, these caveats are acknowledged in the text: Section 4.1 explicitly says the rise is poorly constrained, and Section 7 admits lack of pre-explosion imaging and unconstrained f_rho M. The internal inconsistencies (e.g., the abstract/Table-2 radius range versus Section 7's 14.6-57.1 R_sun) do not destroy the central claim; they only weaken the precision of the quoted progenitor properties. The most load-bearing specific concern is that the quoted radius range is the union of four model posteriors spanning a factor of four, so the claim 'R=14.6-57.1 R_sun' is not a single-consistent measurement. Because the authors themselves flag the model degeneracy and the fits are reproducible from publicly available fitting packages, the paper's broad conclusion (a moderately stripped, not-very-extended progenitor) remains defensible. The suggested test directly addresses whether the radius interval is robust to the one free choice that is most likely to change the answer: where t0 is placed within the non-detection-to-discovery window. If the test shows instability, the verdict should be CONDITIONAL and the abstract should quote model-dependent intervals; if stable, the paper stands as is. Either way the reader's CONDITIONAL for data release and clearer framing is appropriate, and no new objection beyond the reader's is needed.","tokens_in":28221,"tokens_out":1807,"duration_ms":16592,"concrete_test":"Re-run the four shock-cooling fits twice: (1) with t0 fixed to the adopted midpoint MJD 60558.63, and (2) with t0 as a free parameter with a flat prior over MJD 60557.16-60560.11, while keeping the same data-selection criterion. If the fitted radii and their spread change substantially (e.g., if the P21 and MSW23 posterior ranges no longer overlap, or if the union interval widens by more than ~20%), then the quoted 14.6-57.1 R_sun radius range is not robust and should be reported as model-dependent intervals. Further, verify that the same data points are selected when t0 is shifted within the uncertainty window; if different subsets are used, the comparison of model radii is not apples-to-apples.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The central claim that SN 2024uwq's progenitor is a partially stripped blue/yellow supergiant with R=14.6-57.1 R_sun rests on fits to four analytic shock-cooling models (SW17 n=1.5, SW17 n=3, P21, MSW23). Table 2 shows the fitted radii differ by a factor of about four (P21: 14.6+/-0.4 R_sun; MSW23: 57.1+/-7.2 R_sun), and the quoted range is simply the union of the four model posteriors, not a measurement with a single physical interpretation. The paper itself notes the rise to the early excess was not observed (Section 4.1: 'The rise from first detection to the early excess is poorly constrained'), so the data used for the fits are all on the declining side of the excess. Also, the explosion epoch t0 = MJD 60558.63 +/- 1.5 is the midpoint of a 3-day gap between non-detection and discovery; the fitted t0 values in Table 2 span 60558.8-60560.1, and shifting t0 within the allowed window changes which points are selected for the shock-cooling fit and can bias the inferred radius. The fits also use assumed temperature/validity cuts and an unconstrained f_rho M parameter, and the P21 fit explicitly excludes the intrinsic scatter term that the other fits include, making the quoted P21 errors not directly comparable.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The paper presents early-time multiwavelength photometry and spectroscopy of the Type IIb supernova SN 2024uwq, combining ATLAS, Las Cumbres, DLT40, and Swift UVOT photometry with FLOYDS, SALT, SOAR, and Gemini-South spectroscopy. The authors identify a double-peaked light curve with an initial excess that they interpret as shock-cooling emission, followed by a radioactive-powered second peak. Spectral evolution shows broad H-alpha decreasing in strength while He I lines strengthen, consistent with a thin hydrogen envelope over helium-rich ejecta. They fit four analytic shock-cooling models (SW17 with n=1.5 and n=3, P21, MSW23) and a two-component Arnett model to infer progenitor properties, obtaining R = 14.6-57.1 R_sun, M_env = 0.7-1.35 M_sun, M_ej ~ 3 M_sun, and M_Ni ~ 0.1 M_sun. From these they argue that the progenitor was a 12-20 M_sun ZAMS blue/yellow supergiant likely stripped by binary interaction, occupying a transitional position between compact and extended Type IIb progenitors. The paper also estimates detectability of similar events with ULTRASAT, UVEX, and LSST.","tokens_in":28429,"tokens_out":7252,"duration_ms":78051,"significance":"If the progenitor constraints hold, SN 2024uwq is a valuable addition to the small sample of Type IIb supernovae with resolved shock-cooling emission and may probe the transition between compact and extended stripped-envelope progenitors. The observational dataset is genuinely strong: UV and optical coverage near the first peak, high-cadence spectra over several weeks, NIR spectroscopy with a plausible CO detection, and careful comparison with literature SNe. The paper also makes constructive use of public fitting packages, which aids reproducibility. However, the quantitative radius constraint is weaker than the abstract implies: the four shock-cooling models yield median radii spanning a factor of about four, and the quoted range is the union of model-specific posteriors rather than a single validated measurement. The enduring value of the paper lies more in the well-characterized transient and its placement in the Type IIb diversity than in a precise progenitor radius.","major_comments":[{"comment":"The headline progenitor-radius constraint R = 14.6-57.1 R_sun is the union of four model-specific posterior intervals (P21: 14.61 +/- 0.36; SW17 n=1.5: 35.71; SW17 n=3: 50.0; MSW23: 57.14 +/- 7.20 R_sun) and is not a single physical measurement. Because the models make different structural assumptions, the factor-of-four spread is a systematic/model uncertainty rather than a statistical one. The abstract's R = 10-60 R_sun and the Section 7 statement that the progenitor is a BSG/YSG with R = 14.6-57.1 R_sun therefore overstate the constraint. Please provide a combined estimate via explicit model weighting or an added systematic term, or rephrase the conclusion as a model-dependent range.","section":"Section 7, Table 2"},{"comment":"The rise to the early excess is not observed: Section 4.1 states that 'the rise from first detection to the early excess is poorly constrained' and Figure 2 shows that nearly all bands begin after the excess peak. The shock-cooling fits are therefore anchored only on the declining side of the excess, so the inferred radius depends on each model's extrapolation of the unobserved rising phase. This degeneracy likely contributes to the factor-of-four spread in Table 2. Please demonstrate robustness by excluding the earliest ATLAS-o point and by shifting t0 within the allowed non-detection/discovery window; if the constraints broaden substantially, present the result as a broad range or limit rather than a precise radius.","section":"Section 4.1, Figure 2, Section 6"},{"comment":"The validity cut for shock-cooling modeling is stated inconsistently. Section 4.3 says the cut is based on temperatures '>= 8120 K (0.7 eV)', while Section 6 says observations are selected 'where the effective temperature (Teff) is less than 0.7 eV'. Since this criterion determines which photometric points enter the fits, the contradiction is load-bearing. Please correct the typo, state the exact cut, and verify that the fits in Table 2 and Figure 9 use the intended data set.","section":"Section 4.3 vs Section 6"},{"comment":"The explosion epoch t0 is assumed as the midpoint of a ~3 day non-detection/discovery gap (MJD 60558.63 +/- 1.5), and the fitted t0 values in Table 2 span MJD 60558.80 to 60560.10. P21's t0 sits near the discovery edge, while the SW17 and MSW23 fits prefer earlier times by about 1-2 days. The fitted radii are entangled with the assumed t0, but the quoted R and M_env ranges do not propagate the +/- 1.5 day t0 uncertainty. Please include a sensitivity check with t0 fixed at the non-detection and discovery extremes, or treat t0 as a nuisance parameter in the quoted credible intervals.","section":"Section 6, Table 2"}],"minor_comments":[{"comment":"The abstract gives R = 10-60 R_sun while Table 2 and Section 7 give R = 14.6-57.1 R_sun; please use one consistent range throughout.","section":"Abstract and Table 2"},{"comment":"The text references 'Equation A3', but the Appendix contains no equations; either include the equation or remove the reference.","section":"Section 4.3"},{"comment":"The fitted shock-cooling end time ts = 4.94+0.042/-0.079 days appears to have the asymmetric errors written in an unusual order and is not clearly defined in the text; please clarify.","section":"Section 4.3"},{"comment":"The phrase 'The tighter constraints in P21 arise from non-exclusion of intrinsic scatter parameter' is confusing because Table 2 shows no sigma entry for P21; the intended meaning is likely 'non-inclusion'.","section":"Section 7"},{"comment":"The caption says 'Black and grey lines depict two and one component models', but the legend or line styles in the figure are not labeled; please add a clear legend.","section":"Figure 4 caption"},{"comment":"The text 'PI: Jah' is likely a typo for 'PI: Jha'; please correct.","section":"Acknowledgments"}],"recommendation":"major_revision","confidential_remarks":"The observational dataset is solid and the transient is well characterized, but the central radius claim is currently overstated because the quoted range is the union of four model posteriors rather than a model-validated measurement. The requested revisions—reframing the radius as model-dependent, resolving the validity-cut contradiction, and adding t0-sensitivity tests—are feasible within the scope of the paper. I would support acceptance after these revisions are made."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Main takeaway: this is a solid observational paper with a genuinely new dataset and a defensible but softer-than-advertised progenitor constraint. SN 2024uwq is now a well-observed Type IIb: early Swift UV plus optical photometry, multi-epoch optical spectra, a NIR spectrum, a double-peaked light curve, and a clear shock-cooling excess. The classification and the spectral evolution (H-alpha fading, He I strengthening) are convincing. The two-zone Arnett analysis gives normal IIb parameters (Mej ~3 M_sun, Ni ~0.1 M_sun) and the paper is honest about its limitations: no pre-explosion imaging, no observed rise to the early excess, unconstrained f_rho M, and the Arnett model's late-time failure. The broad claim—a partially stripped blue/yellow supergiant, probably binary-stripped—is reasonable and not circular: the SW17/P21/MSW23 models are external, and the data are new. The citation pattern looks appropriate; the comparison sample is standard. The soft spot is exactly what the stress-test note says. The 14.6–57.1 R_sun radius is the union of four model posteriors, not a single measurement. P21 wants ~15 R_sun, MSW23 wants ~57 R_sun, and the difference is structural, not noise. On top of that, the rise to the shock-cooling peak is unobserved, t0 sits in a 3-day gap, the P21 t0 posterior lands at the edge of the prior (MJD 60560.10 ± 0.01), and the P21 fit excludes the intrinsic scatter term the others include, so its error bars are not directly comparable. These issues should be stated as model-dependent intervals, and the abstract's \"10–60 R_sun\" versus the body's \"14.6–57.1 R_sun\" should be reconciled. There is also an internal inconsistency in the validity cut: Section 4.3 says T ≥ 8120 K (0.7 eV) is the valid regime, while Section 6 says Teff < 0.7 eV. One of those is backwards, and it matters for which points enter the fits. Minor but real. Also, no photometry tables or code with commit hashes are provided; for an observational paper whose main product is early-time data, that is a concrete deficiency. None of this sinks the paper. The central physical picture is likely right in broad strokes. But the exact radius and envelope mass need to be framed as model-dependent, and the data should be released. This deserves peer review; it is exactly the kind of object paper that builds the empirical sample. With revisions on framing and data release, I would publish.","headline":"A new, well-observed Type IIb whose shock-cooling data support a partially stripped progenitor, but the quoted radius range is a model-dependent union, not a single measurement.","tokens_in":796,"tokens_out":855,"would_cite":true,"duration_ms":60759,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":["97.60.Bw"],"model":"deepseek-v4-flash","headline":"Early flash of SN 2024uwq reveals a partially stripped supergiant","keywords":["core-collapse supernovae","Type IIb supernovae","shock cooling emission","stripped-envelope supernovae","supernova progenitors","binary mass transfer","double-peaked light curve","SN 2024uwq"],"falsifier":"A decisive test would be to catch a similar Type IIb with continuous coverage of the rise to the shock-cooling peak and an independently known explosion time, then fit the same three models: if they fail to converge on a single radius, the analytic shock-cooling interpretation is suspect. A second test is a deep pre-explosion image resolving the supernova site, since a detected progenitor outside the 15 to 57 solar radius range would contradict the claim.","tokens_in":27910,"feed_emoji":"💥","tokens_out":8409,"duration_ms":87331,"temperature":0.7,"pith_summary":"This paper argues that SN 2024uwq, a Type IIb supernova in NGC 6902, exploded from a partially stripped blue or yellow supergiant rather than a red supergiant. Its double-peaked light curve shows an early excess that the authors identify as shock-cooling emission from a thin hydrogen envelope, and fitting that excess with three analytic models yields a progenitor radius of $R = 14.6$–$57.1\\,R_\\odot$ and an envelope mass of $M_{\\rm env} = 0.7$–$1.35\\,M_\\odot$. The spectra support the picture: hydrogen lines fade while helium lines strengthen over weeks, consistent with a modest hydrogen layer over helium-rich ejecta. The paper places SN 2024uwq between compact and extended Type IIb supernovae and argues that binary mass stripping, not single-star winds, best explains the inferred envelope. If correct, the event is a direct probe of how binary mass-transfer efficiency shapes the diversity of stripped-envelope supernova progenitors.","feed_headline":"Early flash of SN 2024uwq reveals a partially stripped supergiant","feed_subtitle":"Shock-cooling light pins the star to 15-57 solar radii and a 12-20 solar mass origin.","key_machinery":"The load-bearing tool is the analytic shock-cooling emission model, which connects the early UV/optical excess to the progenitor's radius and envelope mass. The paper applies three variants of this model to the first 3.5 days of multiband photometry, restricting the fits to blackbody temperatures above 0.7 eV where the models are valid. The argument is carried by the combination of that early excess with spectral line evolution: absorption-and-emission (P-Cygni) profiles of H$\\alpha$ and He I show the hydrogen envelope thinning as helium-rich ejecta are exposed, and a two-component bolometric light-curve fit anchors the ejecta mass, nickel mass, and kinetic energy.","core_discovery":"The central discovery is that the early excess in SN 2024uwq's light curve can be read as a fossil of the progenitor's outer layers. Modeling the first roughly 3.5 days of multiband emission with three analytic shock-cooling frameworks converges on a progenitor with radius between about 15 and 57 solar radii and a hydrogen envelope of order one solar mass, ruling out a canonical red supergiant. The double-peaked light curve, the velocity decline of H$\\alpha$ from roughly 15,500 to 10,000 km s$^{-1}$, and the strengthening of He I lines all agree with a partially stripped blue or yellow supergiant. Combining the ejecta mass from a two-component analytic bolometric fit with a neutron-star remnant, the pre-supernova mass is about 4.4 solar masses, pointing to a 12–20 solar mass main-sequence star; because single-star winds cannot shed enough hydrogen at these masses, the paper concludes that binary interaction is the likely stripping agent.","pith_inferences":["Editorial inference: the factor-of-four spread between the compact and extended model radii (14.6 versus 57.1 solar radii) is likely a systematic floor for every Type IIb analyzed this way, so population comparisons should quote the model spread rather than a single fit.","Editorial inference: a clean test of the binary-stripping story would be a search for a surviving companion star in deep late-time imaging; detecting a blue excess or radial-velocity variation at the supernova site would directly support the binary hypothesis.","Editorial inference: if the shock-cooling interpretation is right, then the same early excess should appear in the near-UV for similar events out to roughly 200 Mpc, and wide-field UV surveys should catch several per year with fully sampled rises, allowing the radius-envelope mass plane to be mapped empirically.","Editorial inference: the unobserved rise to the first peak is the main observational weakness; an event caught within hours by a high-cadence UV survey would settle whether the analytic models recover the true progenitor radius or are degenerate with the assumed explosion time."],"forward_implications":["The progenitor of SN 2024uwq was a partially stripped blue or yellow supergiant, not a red supergiant, adding to evidence that many Type IIb supernovae come from compact, stripped stars.","Binary mass transfer, rather than single-star wind mass loss, is the more natural way to produce a roughly one-solar-mass hydrogen envelope on a 12–20 solar mass main-sequence star.","SN 2024uwq occupies the gap between compact Type IIb events and extended ones, supporting a continuum of envelope stripping set by binary mass-transfer efficiency.","Early UV and optical observations are necessary to resolve shock-cooling phases; without them the progenitor radius and envelope mass constraints are much weaker.","The event's ejecta mass of about 3 solar masses, nickel mass of about 0.1 solar masses, and kinetic energy of about $2.75\\times10^{51}$ erg agree with the broader stripped-envelope supernova population."],"supporting_citations":[{"why":"Supplies the analytic shock-cooling emission model used for the spherical-phase fits, including the temperature validity cut.","marker":"Sapir & Waxman (2017)"},{"why":"Provides the broken-power-law shock-cooling model that yields the compact radius fit of about 14.6 solar radii.","marker":"Piro et al. (2021)"},{"why":"Provides the hydrodynamically calibrated shock-cooling model with line blanketing that yields the more extended radius fit and best UV match.","marker":"Morag et al. (2023)"},{"why":"Demonstrates early shock-cooling excess in Type IIb supernovae and supplies the SN 2016gkg light-curve framework used for comparison.","marker":"Arcavi et al. (2017)"},{"why":"Supplies SN 2016gkg photometry and spectra, the closest observed analog for SN 2024uwq's early evolution.","marker":"Tartaglia et al. (2017)"},{"why":"Provides the SN 1993J envelope mass comparison and the interpretation of hydrogen-rich ejecta over helium cores.","marker":"Woosley et al. (1994)"},{"why":"Shows that binary mass transfer can strip hydrogen envelopes to 0.1–1.5 solar masses, supporting the binary-stripping scenario.","marker":"Yoon et al. (2017)"},{"why":"Introduces the compact versus extended Type IIb classification used to place SN 2024uwq in the progenitor phase space.","marker":"Chevalier & Soderberg (2010)"},{"why":"Supplies pre-explosion imaging-based progenitor constraints for SN 2016gkg, a key comparison in the radius-envelope mass diagram.","marker":"Kilpatrick et al. (2022)"}],"fun_headline_variants":["Shock-cooling light pins SN 2024uwq to a partially stripped star","Double-peaked supernova reveals a binary-stripped progenitor","Early shock cooling fingerprints SN 2024uwq's progenitor","SN 2024uwq's double peak points to a binary-stripped star","Shock-cooling envelope pinpoints a blue supergiant in SN 2024uwq"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The inference stands or falls on the assumption that the early excess is shock-cooling emission from the progenitor envelope, described by the analytic models, with an explosion epoch taken as the midpoint between a non-detection and discovery, uncertain to about plus or minus 1.5 days.","fun_headline_variants_meta":{"raw":{"variants":["Shock-cooling light pins SN 2024uwq to a partially stripped star","Double-peaked supernova reveals a binary-stripped progenitor","Early shock cooling fingerprints SN 2024uwq's progenitor","SN 2024uwq's double peak points to a binary-stripped star","Shock-cooling envelope pinpoints a blue supergiant in SN 2024uwq"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000976,"raw_usage":{"total_tokens":4192,"prompt_tokens":1039,"completion_tokens":3153,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":655,"completion_tokens_details":{"reasoning_tokens":3050}},"tokens_in":655,"tokens_out":3153,"duration_ms":25901,"temperature":1.0,"reasoning_tokens":3050,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-16T00:40:01.308106+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"A decisive test would be to catch a similar Type IIb with continuous coverage of the rise to the shock-cooling peak and an independently known explosion time, then fit the same three models: if they fail to converge on a single radius, the analytic shock-cooling interpretation is suspect. A second test is a deep pre-explosion image resolving the supernova site, since a detected progenitor outside the 15 to 57 solar radius range would contradict the claim.","supporting_citations":[{"cited_title":"D., Coulter , D","cited_arxiv_id":null,"evidence_quote":"Supplies pre-explosion imaging-based progenitor constraints for SN 2016gkg, a key comparison in the radius-envelope mass diagram."}],"review_version":1}