{"id":"c41b4468-fbd2-437d-b80d-afd06ea77e97","arxiv_id":"2412.03411","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":6,"one_line_summary":"TOI-1685 b's JWST phase curve shows no atmospheric features and a dayside brightness temperature consistent with a low-albedo, airless blackbody.","lead":"JWST observations of the rocky super-Earth TOI-1685 b reveal a featureless transmission and emission spectrum, consistent with a dark, bare rock with no significant atmosphere. This full-orbit NIRSpec phase curve adds a new data point to the small sample of airless M-star planets, helping map where atmospheres can survive.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Correlated noise bias in the eclipse depth is not excluded by the prayer-bead analysis, and R=0.98 rests on only the NRS2 detector.","rationale":"The reader's weakest_assumption matches my own: unmodeled correlated noise may bias the eclipse depth and phase-curve parameters, and the prayer-bead method inflates uncertainties without correcting bias. The paper transparently acknowledges the issue in §3.2.2 and §3.3, noting the 2-3 sigma discrepancy between full phase-curve and eclipse-only depths and the 'poor treatment of correlated noise.' Because the final R is taken from NRS2 only and NRS1 is within 1 sigma but higher (R=1.10±0.10), and because the eclipse depth is the direct observable underlying R, the quantitative blackbody claim is not fully secure. The qualitative conclusion of a flat transmission spectrum and no clear H2-dominated atmosphere is robust, since the transit depth is high-S/N and the paper shows the correlated noise does not affect it. A conditional verdict is appropriate: the paper should be accepted on condition that an injection-recovery check demonstrates unbiased eclipse-depth recovery under the observed correlated noise, or that the bare-rock conclusion is reframed more qualitatively. I do not see grounds for rejection, because the paper is transparent, three independent reductions agree, and the qualitative conclusions are well supported.","tokens_in":27068,"tokens_out":2807,"duration_ms":27344,"concrete_test":"Perform an injection-recovery test on the actual NRS2 and NRS1 time-series residuals: inject a synthetic planetary signal with known eclipse depth, phase-curve amplitude, and phase offset at the true ephemeris, then rerun the full Eureka! reduction and the same phase-curve plus prayer-bead fitting pipeline. If the recovered eclipse depth and R are unbiased to within the quoted uncertainties, the bare-rock claim is supported. If the recovered signal is biased by an amount comparable to the observed Full-vs-Combined eclipse-depth discrepancy (2-3 sigma), the concern is validated and the quoted R=0.98±0.07 must be revised or explicitly flagged as systematically uncertain.","verdict_should_be":"CONDITIONAL","load_bearing_attack":"The central claim, that TOI-1685 b is a dark bare rock, depends on the dayside brightness temperature ratio R from emission and on no heat redistribution from the phase curve. The paper's own §3.2.2 and §3.3 show that the eclipse depth is 2-3 sigma larger in the full phase-curve fit than in eclipse-only fits, with residual RMS 145-170 ppm, comparable to the eclipse signal. The prayer-bead method preserves the residual ordering and refits, so it inflates uncertainties but does not correct a systematic bias in the eclipse depth or in the phase-curve parameters C1 and D1 if the correlated noise is not fully absorbed. The paper actually states that the full phase-curve eclipse depths are 'too deep compared to the maximum expected given the planet's temperature and indicative of poor treatment of correlated noise.' The quoted R=0.98±0.07 comes from NRS2 alone; NRS1 gives R=1.10±0.10. An eclipse-depth bias of order tens of ppm would shift R by ~0.1, potentially moving it off the blackbody value. The transmission-spectrum flatness is more robust because the high-S/N transit depth is largely insensitive to the correlated noise, as the paper notes. The load-bearing weakness is therefore not the qualitative direction of a thin or absent atmosphere, but the quantitative R=0.98 and the specific bare-rock, zero-heat-redistribution interpretation, which could change if the correlated noise imprints on the measured eclipse depth.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The paper presents JWST NIRSpec/G395H full-orbit phase-curve observations of the hot rocky super-Earth TOI-1685 b. Three independent data reductions (Eureka!, Tiberius, ExoTIC-JEDI) produce consistent light curves. The transmission spectrum is flat, ruling out clear H2-dominated atmospheres; the emission spectrum is featureless. A strong correlated-noise component (RMS 145-170 ppm, 2-3 times the eclipse depth) is present in both detectors, with different characteristic timescales (4.5 h in NRS1, 2.5 h in NRS2). After unsuccessful attempts to remove this noise, the authors use a prayer-bead analysis to inflate uncertainties. From NRS2 white-light data they derive a dayside brightness-temperature ratio R = 0.98 +/- 0.07 relative to a zero-albedo, no-redistribution blackbody, and conclude that TOI-1685 b is likely a dark, bare rock with no significant atmosphere.","tokens_in":27346,"tokens_out":10212,"duration_ms":83754,"significance":"If correct, the paper adds a new data point to the small sample of M-dwarf rocky planets observed in emission, supporting the cosmic-shoreline hypothesis. The strengths are the three independent reductions, the transparent characterization of correlated noise, and the use of forward models and retrievals to interpret the spectra. The main weakness is that the quantitative R and the no-heat-redistribution interpretation rest on data whose residuals are dominated by correlated noise at a level comparable to the signal; the prayer-bead method expands error bars but does not remove potential bias. The qualitative conclusion of a thin or absent atmosphere is plausible, but the paper's quantitative precision is not yet demonstrated.","major_comments":[{"comment":"The central quantitative claim, R = 0.98 +/- 0.07, is taken from the NRS2 white-light phase curve with prayer-bead uncertainties. The data that enter this fit have residual RMS of 170 ppm (NRS2), 2-3 times the eclipse depth, and full phase-curve eclipse depths are 2-3 sigma larger than eclipse-only fits (§3.2.2). The prayer-bead analysis preserves the residual ordering and refits the same model, so it widens the error bars but does not correct a systematic offset in the eclipse depth. An unmodelled correlated component at the eclipse timescale could shift the eclipse depth by tens of ppm and change R by ~0.1. The authors should provide a test that the eclipse depth is insensitive to the correlated noise, for example by deriving R from the eclipse-only fits for NRS2, by fitting the phase curve with a Gaussian-process or periodic-noise model, or by injecting and recovering synthetic eclipses in the actual residuals. Without such a test, the precision of R is not supported.","section":"§3.2.2, §3.3.2, §4.2.1"},{"comment":"The headline R is based on NRS2 alone; NRS1 gives R = 1.10 +/- 0.10 and is discarded because of stronger correlated noise and a linear trend. This is an ad hoc choice, and the paper does not show that the NRS2 value is robust to reasonable alternatives, such as including NRS1 with a more flexible noise model or fitting both detectors jointly. The independent estimate from the low-resolution emission spectrum gives R = 0.94 +/- 0.04 for both detectors, which is formally consistent but not identical to the adopted value. The paper should state explicitly which estimate is adopted for the conclusions, justify that choice, and quantify how much the albedo and heat-redistribution results change if R = 0.94 or R = 1.10 are used instead.","section":"§4.2.1"}],"minor_comments":[{"comment":"The statement that the eclipse depth is 2-3 sigma larger in the full phase-curve fit than in eclipse-only fits is not specified by detector or wavelength; for NRS2 the offset is generally smaller (Table 8). Please quantify for each detector.","section":"§3.2.2"},{"comment":"The sentence 'they are too deep compared to the maximum expected given the planet's temperature' is ambiguous: the NRS2 full phase-curve eclipse depth corresponds to R = 0.98, i.e., near the maximum expected. Please clarify which detector and which comparison are meant.","section":"§3.2.2"},{"comment":"The NRS2 wavelength range is quoted inconsistently: 3.823-5.172 um in the abstract and §3.1, but 3.850-5.172 um in Table 2. Please harmonize.","section":"Abstract, §3.1, Table 2"},{"comment":"The legend of Figure 5 is crowded and the symbols overlap; a separate table of the eclipse-depth values (already in Table 8) would make the figure easier to read.","section":"Figure 5"},{"comment":"The nightside brightness temperature posteriors extend to zero (e.g., Tp,night = 1100+210-1100 K for NRS1); quoting a 95% upper limit would be more informative.","section":"§4.2.1"},{"comment":"The sentence describing the prayer-bead procedure is awkward; consider rephrasing: 'For each bead, we shift the residuals by one exposure time, add them to the best-fit model, and refit the new light curve with the same model and priors.'","section":"§3.3.2"}],"recommendation":"major_revision","confidential_remarks":"The paper is well-written and the authors are appropriately cautious about the correlated noise. The main risk is that the final R and the no-heat-redistribution conclusion are based on a detection that could be biased by the unmodelled noise; the requested robustness tests should be feasible with the existing data. The manuscript is a good fit for the journal's scope. No concerns about citation practices or novelty."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Read the paper. The new thing is a full-orbit NIRSpec G395H phase curve of a hot rocky super-Earth, with three independent reductions agreeing. The transmission spectrum is flat, the emission spectrum is featureless, and the paper is unusually honest about the correlated noise that dominates the residuals. The qualitative conclusion—TOI-1685 b is probably a dark, airless rock—is likely right and fits the growing M-star rocky planet sample.\n\nThe soft spot is quantitative. The eclipse depth is 2-3 sigma deeper when fit with the full phase curve than with eclipses alone, and the residual RMS (145-170 ppm) is comparable to the eclipse signal. The prayer-bead method widens the error bars but does not remove a systematic bias in the eclipse depth or in the phase-curve parameters. The paper says this itself. The headline R=0.98±0.07 comes from NRS2 only; NRS1 gives 1.10±0.10, formally consistent but not reassuring. An eclipse-depth bias of tens of ppm shifts R by ~0.1. So I'd trust the flat transmission spectrum and the no-thick-atmosphere conclusion, but I would not yet quote R=0.98 as a measured surface property.\n\nThe retrieval and forward-model work is reasonable, and the paper does not overclaim. The surface-composition section is appropriately hedged. The main missing piece is an injection test showing that the fitting procedure recovers unbiased eclipse depths under the observed correlated noise, and a more explicit discussion of why NRS1 and NRS2 disagree.\n\nWho is this for? The exoplanet atmosphere community, particularly people working on bare-rock planets and NIRSpec time-series systematics. It deserves a serious referee; the systematics discussion is exactly what the field needs. I'd want the authors to address the NRS1/NRS2 discrepancy and add an injection test before publication, but the paper is a solid addition either way.","headline":"A transparent JWST phase-curve study whose qualitative bare-rock conclusion is plausible, but whose headline brightness-temperature ratio is not yet on solid ground.","tokens_in":27991,"tokens_out":1839,"would_cite":true,"duration_ms":17264,"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":"A full JWST phase curve shows TOI-1685 b is a dark, bare rock whose dayside emission matches a zero-albedo blackbody.","keywords":["TOI-1685 b","exoplanet atmospheres","extrasolar rocky planets","JWST NIRSpec","phase curve","secondary eclipse","Cosmic Shoreline","correlated noise"],"falsifier":"A decisive test is a new eclipse observation with different systematics—for example, a MIRI LRS spectrum or a NIRSpec visit at another roll angle—deep enough to detect or exclude the CO$_2$ band near 4.3 µm; a detected band would falsify the no-atmosphere claim, while a featureless blackbody upper limit would support it.","tokens_in":26801,"feed_emoji":"🪨","tokens_out":17234,"duration_ms":142170,"temperature":0.7,"pith_summary":"This paper reports a 19-hour JWST phase curve of TOI-1685 b, a hot rocky super-Earth orbiting an M-dwarf star, and argues that the planet is a bare rock. The transmission spectrum is flat, ruling out clear hydrogen-dominated atmospheres, and the emission spectrum is featureless. The dayside brightness temperature is $0.98\\pm0.07$ times that of a perfect blackbody in the 3.8–5.2 µm band, with no measurable heat redistribution to the nightside and a very low albedo. If correct, TOI-1685 b joins a growing set of airless rocky planets around M stars and sharpens the empirical 'Cosmic Shoreline' separating planets that hold onto atmospheres from those that lose them. The paper also documents a strong, detector-dependent correlated noise component and uses a conservative resampling technique so the quoted uncertainties reflect it.","feed_headline":"A full JWST orbit shows this super-Earth is a bare rock","feed_subtitle":"Dayside emission is 98% of a blackbody's; nightside stays dark, placing it on the Cosmic Shoreline.","key_machinery":"The load-bearing quantity is the temperature scaling ratio $R\\equiv T_{p,\\mathrm{day}}/T_{p,\\mathrm{max}}$, where $T_{p,\\mathrm{max}}$ is the substellar temperature of a zero-albedo, zero-recirculation blackbody; $R\\approx1$ means the dayside emits like a bare rock. The analysis models the full-orbit white-light and spectroscopic light curves with a transit-plus-sinusoid phase-curve model, fits eclipse-only segments as a cross-check, and inflates the parameter uncertainties with a prayer-bead resampling that preserves the correlated noise structure in the residuals. Forward radiative-transfer models of thin secondary atmospheres and simple single-species retrievals are then compared with the featureless emission spectrum and the flat transmission spectrum to decide which atmospheric cases remain. The longer-wavelength detector provides the quoted value because the shorter-wavelength light curve carries a stronger correlated-noise component and a linear trend that degrade the phase-curve parameters.","core_discovery":"The central claim is that TOI-1685 b's dayside emission is indistinguishable, within $1\\sigma$, from a zero-albedo blackbody with no heat redistribution, making a significant atmosphere unlikely. From the longer-wavelength detector (3.823–5.172 µm) the authors measure a dayside brightness ratio $R = T_{p,\\mathrm{day}}/T_{p,\\mathrm{max}} = 0.98\\pm0.07$, corresponding to a dayside brightness temperature of $1360\\pm100$ K, and a nightside consistent with near-zero emission; the shorter-wavelength detector gives a noisier $R = 1.10\\pm0.10$. The transmission spectrum is flat and rules out clear H$_2$-dominated atmospheres, while emission forward models reject 1-mbar CO$_2$ and SO$_2$ atmospheres and a 10-bar H$_2$O atmosphere, although thinner versions remain possible. The authors conclude that the most probable picture is a dark, airless rock with an Earth-like density, noting that the JWST-derived radius ($1.37$–$1.39$ Earth radii) is slightly smaller than the TESS-based value.","pith_inferences":["We infer that the detector-dependent noise (4.5-hour scale in the blue detector, 2.5-hour in the red) is likely to affect other NIRSpec phase curves, so previously reported eclipse depths from this instrument may carry similar unmodeled systematics unless the analyses used comparably conservative uncertainties.","We infer that the 2–3σ gap between eclipse-only and full-phase-curve depths is the main internal tension: if the eclipse-only values are closer to truth, the dayside would be cooler than the quoted blackbody match, which still supports a bare rock, while if the full-phase-curve values are right, the shorter-wavelength detector's $R=1.10\\pm0.10$ would need a physical explanation.","A testable extension would be to apply the same residual-preserving uncertainty treatment to existing NIRSpec phase curves of other rocky planets and compare noise timescales and eclipse-depth biases across detectors, which could confirm an instrumental origin."],"forward_implications":["If TOI-1685 b is truly airless, it becomes a new anchor point on the Cosmic Shoreline, showing that rocky planets near 1000 K around M dwarfs do not retain detectable atmospheres.","The data put quantitative limits on secondary atmospheres: clear 1-mbar CO$_2$ and SO$_2$ atmospheres and a 10-bar H$_2$O atmosphere are rejected, so any surviving atmosphere must be thinner, cloudier, or less absorbing.","The JWST transit photometry revises the planet radius down to 1.37–1.39 Earth radii, making the bulk density consistent with an Earth-like, iron-bearing composition rather than a water-rich one.","The detector-dependent correlated noise documented here implies that NIRSpec long time-series measurements of ~100 ppm signals need conservative noise treatment before eclipse depths are trusted.","Because the NIRSpec band cannot separate surface mineralogies, the paper's conclusion makes longer-wavelength emission observations (for example, many MIRI LRS visits) the clear next step for identifying what the bare surface is made of."],"supporting_citations":[{"why":"Supplies the stellar parameters, orbital priors, and the earlier TESS-based radius and density used as inputs and comparison for the JWST measurements.","marker":"Burt et al. (2024)"},{"why":"Defines the effective albedo and heat-recirculation efficiency used to interpret the phase-curve amplitude and offset.","marker":"Cowan & Agol (2011)"},{"why":"Introduces the prayer-bead method used to expand parameter uncertainties under correlated noise, producing the final quoted error bars.","marker":"Cowan et al. (2012)"},{"why":"The first bare-rock phase curve of a rocky M-dwarf planet (LHS 3844 b), the template this result is compared against.","marker":"Kreidberg et al. (2019)"},{"why":"Provides the brightness-temperature and forward-model methodology for JWST emission observations of rocky planets and a comparable bare-rock result for GJ 367 b.","marker":"Zhang et al. (2024)"},{"why":"Offers the GJ 1132 b result and the albedo/heat-redistribution comparison with airless Solar System bodies used to contextualize TOI-1685 b.","marker":"Xue et al. (2024)"},{"why":"Supplies the surface emission and reflectance models for airless rocky bodies used to assess what the NIRSpec data can say about surface composition.","marker":"Hu et al. (2012)"},{"why":"Provides the heat-redistribution scaling law used in the forward atmospheric models to estimate redistribution for each candidate atmosphere.","marker":"Koll (2022)"},{"why":"Supplies the retrieval framework used to reject a clear H$_2$-dominated atmosphere in transmission and explore single-species secondary atmospheres.","marker":"Al-Refaie et al. (2022)"}],"fun_headline_variants":["JWST phase curve finds TOI-1685 b is a dark, airless rock","Bare rock super-Earth: TOI-1685 b matches a zero-albedo blackbody","TOI-1685 b: a dark, bare rock from JWST phase curve","JWST reveals super-Earth TOI-1685 b as a blackbody-like rock"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The bare-rock conclusion assumes that the strong, hour-scale correlated noise seen in the light curves shifts the measured eclipse depths and phase-curve parameters by random amounts rather than systematically.","fun_headline_variants_meta":{"raw":{"variants":["JWST phase curve finds TOI-1685 b is a dark, airless rock","Bare rock super-Earth: TOI-1685 b matches a zero-albedo blackbody","TOI-1685 b: a dark, bare rock from JWST phase curve","JWST reveals super-Earth TOI-1685 b as a blackbody-like rock"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000229,"raw_usage":{"total_tokens":1561,"prompt_tokens":1113,"completion_tokens":448,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":729,"completion_tokens_details":{"reasoning_tokens":351}},"tokens_in":729,"tokens_out":448,"duration_ms":4197,"temperature":1.0,"reasoning_tokens":351,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-11T22:25:06.327096+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"A decisive test is a new eclipse observation with different systematics—for example, a MIRI LRS spectrum or a NIRSpec visit at another roll angle—deep enough to detect or exclude the CO$_2$ band near 4.3 µm; a detected band would falsify the no-atmosphere claim, while a featureless blackbody upper limit would support it.","supporting_citations":[{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Provides the heat-redistribution scaling law used in the forward atmospheric models to estimate redistribution for each candidate atmosphere."}],"review_version":1}