{"id":"fb8ebc47-19e5-4af1-a6c4-5f76c722a990","arxiv_id":"2505.06358","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":3,"one_line_summary":"A new inner super-Earth, TOI-2076 e (radius 1.35 R_Earth, period 3.022 days), is detected in the young TOI-2076 system, and the system age is refined to 210 ± 20 Myr.","lead":"Astronomers report a fourth, smaller planet called TOI-2076 e, orbiting a young Sun-like star every 3 days, and refine the age of the star and its co-moving companions to 210 ± 20 million years. The find matters for understanding how young planetary systems evolve, because it adds a small planet to a young multi-planet system and sharpens the context for JWST observations.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"The discovery claim rests on a 3.02 d signal seen only in the custom light curve; the paper lacks a direct test that the custom detrending cannot manufacture a low-SNR transit-like systematic.","rationale":"The reader's weakest assumption is precisely the custom-detrending concern, and I agree that it is the most load-bearing issue. The paper's strongest evidence for TOI-2076 e is the coherent phase-folded transit in custom-extracted light curves, supported by a low TRICERATOPS FPP, companion exclusion from imaging and spectroscopy, and consistency across sectors. But none of these directly rules out a systematic introduced by the Section 2.1 linear detrending model, especially because the signal is absent from PDCSAP/SAP. The injection-recovery analysis demonstrates sensitivity to injected transits but cannot diagnose spurious signals created by the detrending itself. A control-sample or split-sector test would settle the question. The age analysis is secondary and, while it inherits some arbitrariness in the membership cuts, the multiple independent methods and explicit discussion of limitations make it less risky than the detection itself. I therefore keep the reader's CONDITIONAL verdict unchanged: the planet is plausible and the paper is honest, but confirmation from independent photometry or a direct null test is needed before full acceptance.","tokens_in":50140,"tokens_out":4005,"duration_ms":46994,"concrete_test":"Run the exact Section 2.1 extraction and Section 3 Notch+BLS search on 50 TESS targets of comparable brightness and stellar variability that are not known planet hosts, using the same custom detrending choices. Count how many yield a peak at 3.022 ± 0.005 d with SNR ≥ 17 and depth 150–350 ppm. Independently, run the same search separately on Sector 16+23 data and Sector 50+77 data; if the signal is recovered in only one subset, or if the control-star false-alarm rate is more than a few percent, the 3.02 d signal should be treated as a detrending artifact rather than a planet.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The central claim is that TOI-2076 e is real, which requires the 3.0223445 d, ~240 ppm signal in the custom-extracted TESS photometry to be astrophysical rather than a detrending artifact. The paper's Figure 1 shows the signal is not recovered at sufficient SNR in PDCSAP or SAP, so the detection depends entirely on the Section 2.1 pipeline: a basis spline with 0.2 d breaks, quaternion co-trending, seven PDC band-3 vectors, and a 0.1 d high-pass background term. Because the transit is shallow and the detrending model is flexible at timescales comparable to the 2.16 h transit, a small coherent systematic at 3.022 d in one or more sectors could survive and produce the observed phase-folded signal. The Section 7 injection-recovery tests completeness, not the false-positive rate; it cannot catch a systematic that the detrending itself generates. Section 6 validation (TRICERATOPS on the flattened light curve, imaging and RV companion rejection, multi-transit prior) argues against a blended eclipsing binary but does not test the detrending hypothesis. The authors are transparent that the signal is absent from standard light curves, but the load-bearing condition that the custom systematic model is not the source of the 3.02 d periodicity remains unsecured.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The paper reports the discovery of a fourth transiting planet, TOI-2076 e, in the young multi-planet system TOI-2076. The planet has an orbital period of 3.0223445 days and a radius of 1.355 Earth radii, detected with SNR 17 in a custom-extracted TESS light curve but not recovered at sufficient SNR in the standard PDCSAP/SAP light curves. The authors update the age of the co-moving population Crius 224 to 210 +/- 20 Myr using gyrochronology, lithium equivalent widths, isochronal modeling, and variability-based aging, and discuss the system's place in young-planet demographics, including a tentative 6.25-day candidate that would complete a resonance chain.","tokens_in":50398,"tokens_out":5703,"duration_ms":55765,"significance":"If the detection is real, the paper adds a rare small planet to a young multi-planet system, providing a direct test of intra-system uniformity evolution and aiding interpretation of existing TTV and JWST observations of the system. The age update, if robust, is valuable for all four planets in TOI-2076 and for the co-moving TOI-1807. The paper is transparent about the detection's dependence on the custom pipeline, makes its TESS data products available via MAST DOIs, and reuses substantial prior imaging and radial-velocity constraints to rule out companions. The main weakness is that the transit signal is not seen in standard light curves, leaving an unquantified risk that the custom detrending itself produces the 3.02-day, transit-shaped signal; a direct robustness test is needed before the discovery claim can be fully accepted.","major_comments":[{"comment":"The detection of TOI-2076 e rests entirely on the custom light-curve extraction of Section 2.1; the signal is not recovered at SNR>7 in PDCSAP or SAP and only at SNR~10 with a high-pass filter on the custom extraction. The injection-recovery analysis of Section 7 measures completeness but cannot detect a false positive generated by the detrending model itself. Because the detrending basis spline has 0.2-day breaks and the transit duration is 0.09 days, a mild coherent systematic at 3.02 days could in principle survive. I request a direct test: (a) inject a synthetic 1.35-R_Earth planet signal into the raw SAP light curve and verify that the full Section 2.1 pipeline recovers it at the expected depth; (b) re-run the search after varying the detrending configuration (e.g., spline break spacing, number of PDC vectors, or excluding quaternion terms) and show that the 3.02-day signal persists with a consistent ephemeris and depth; and (c) provide a quantitative per-sector phase-folded transit depth consistency check rather than only a visual statement.","section":"Sections 2.1 and 3, Figure 1"},{"comment":"The combined age of 210+/-20 Myr is derived from four methods that are not independent, as the authors note, yet the paper does not specify how the individual posteriors were combined. The reported uncertainty is smaller than that of any individual method (gyro 238+69/-60 Myr, Li 210+45/-37 Myr, isochrone 197+/-26 Myr, EVA 252+121/-82 Myr), which suggests a possible undercount of correlated systematic uncertainty. Please state the combination rule (e.g., product of posterior densities, or a hierarchical model) and, if the rule is a simple product, discuss why the 20 Myr uncertainty is not an underestimate given the known correlations among gyrochronology, lithium, and variability ages.","section":"Section 9.5"},{"comment":"The membership list for the age analysis is based on elliptical cuts whose parameters are described as \"somewhat arbitrary\" and which exclude many candidate members. The final age is sensitive to the membership list through all four age methods. Please include a sensitivity test in which the ellipse cuts are varied (e.g., scaling the semi-axes by 0.8 and 1.2) and report the resulting range in the combined age. This would establish that the quoted 210+/-20 Myr is not an artifact of the chosen cuts.","section":"Section 8"}],"minor_comments":[{"comment":"\"Adopted an uncertainty of 0.0005 for sectors 19 and 23\" appears to be a typo for sectors 16 and 23, based on the sector list in Section 2.","section":"Section 2.1"},{"comment":"\"We preformed an injection-recovery analysis\" should be \"We performed an injection-recovery analysis.\"","section":"Section 7"},{"comment":"\"We exacted light curves\" should be \"We extracted light curves.\"","section":"Section 11"},{"comment":"The phrase \"using a single SHO following the description in Gilbert et al. (2022)\" is ambiguous; please specify whether this is the same as one celerite2 RotationTerm oscillator or a different kernel.","section":"Section 5"},{"comment":"The naming of the tentative 6.25-day signal is inconsistent: Figure 3 uses \"TOI 2076 f\" while the text uses \"TOI-2076 f\"; unify the hyphenation throughout.","section":"Table 4 and Figure 3"}],"recommendation":"major_revision","confidential_remarks":"The paper fits the journal's scope well and the authors have been transparent about the detection's dependence on the custom pipeline. The main revision needed is a robustness test of the detrending against false-positive generation; without that, the central discovery claim remains unsecured. The age-analysis issues are secondary but should also be addressed because the age is a headline result."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"You should know two things about this one. First, the paper does real work: it reports a new 1.35 R_Earth planet at 3.02 days in TOI-2076, and it re-derives the group age as 210 ± 20 Myr, which is tighter and more credible than previous estimates that scattered from ~200 Myr to 2.7 Gyr. Second, the planet detection is only visible in their custom light curve, not in the standard PDCSAP/SAP products. That is the whole ballgame. If the custom detrending—basis spline, quaternion co-trending, PDC vectors—manufactured a 3.02-day systematic, the planet is not real.\n\nWhat the paper does well: the false-positive analysis is thorough. They use prior imaging, spectra, and RV limits to rule out blends, and they are honest about the TRICERATOPS caveat. The age analysis is the strongest part: they combine gyrochronology, lithium, isochrone fitting, and variability, using a defined membership list, and the methods cross-check each other. The 210 ± 20 Myr result is plausible and consistent with independent constraints (TOI-1807, the A star HD 153808). They also flag a 6.25-day candidate that would complete a resonance chain but do not overclaim it—that is the opposite of circular confirmation.\n\nWhere the soft spots are: the custom-pipeline dependence is real. The injection-recovery tests completeness, not false-positive rate, and cannot catch a systematic the detrending itself creates. The authors acknowledge the signal is absent from standard light curves, which is good transparency, but they do not provide a direct test that the detrending model is not responsible. That is a legitimate concern, though not fatal: the signal is consistent across four sectors spanning four years, which argues against a transient instrumental artifact. The membership cuts for the age analysis are admittedly arbitrary ellipses, but they check that outside stars are mostly slow rotators, which gives some empirical support. The updated age is a solid improvement, but it inherits the usual systematics of gyrochronology and lithium calibration.\n\nNet: this is a valuable demographic data point and a useful age revision. The planet claim deserves confirmation—ideally independent photometry or additional TESS sectors—but the paper is honest, reproducible in its methods, and the age analysis stands on its own. I would send this to peer review. The right referee will focus on the custom detrending and ask for a direct test that the 3.02-day signal is not a systematic.","headline":"A plausible, well-documented fourth planet in a young system, with an age update that is likely more right than wrong; the detection rests on custom photometry, so the right call is to referee it with confirmation in mind.","tokens_in":50948,"tokens_out":666,"would_cite":true,"duration_ms":9181,"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":"The paper reports the detection of TOI-2076 e, a 1.36-Earth-radius super-Earth on a 3.02-day orbit, making TOI-2076 a four-planet system, and revises the age of its parent population to 210 ± 20 Myr.","keywords":["young exoplanets","super-Earth","TESS","transit detection","multi-planet system","gyrochronology","stellar age","TOI-2076"],"falsifier":"Re-reduce the raw TESS pixel data for TOI-2076 with an independent detrending method that does not use the same basis-spline, quaternion, and PDC co-trending vectors, then check whether a 3.0223445-day transit of roughly 1.6% depth persists coherently across Sectors 16, 23, 50, and 77; alternatively, observe the next predicted transits with ground-based photometry or new TESS sectors.","tokens_in":49942,"feed_emoji":"🪐","tokens_out":5725,"duration_ms":52634,"temperature":0.7,"pith_summary":"This paper reports a fourth, smaller planet in the young multi-planet system TOI-2076. TOI-2076 e is a super-Earth about 1.36 times the radius of Earth on a 3.02-day orbit, interior to the three previously known sub-Neptune-sized planets. The claim matters because it turns TOI-2076 into a rare young system with a small inner planet, giving a direct test of whether planet systems become uniform in radius and period as they age. The paper also updates the age of the system's parent population, Crius 224, to 210 ± 20 Myr by combining rotation, lithium, isochronal, and variability ages.","feed_headline":"A fourth, smaller planet hides inside TOI-2076","feed_subtitle":"Reprocessed TESS data reveal a 3-day, 1.36-Earth-radius world and pin the system's age near 210 million years.","key_machinery":"The detection rests on two pieces. First, a custom light-curve extraction that models SPOC SAP photometry with a basis spline, quaternion co-trending moments, seven co-trending vectors from the PDC band-3 correction, and a background high-pass series; this suppresses stellar activity and spacecraft systematics enough to expose a roughly 0.15% transit. Second, the Notch and LOCoR pipeline, which fits trapezoidal transit shapes at each point and searches the resulting Bayesian Information Criterion time series for periodic signals; the 3.02-day signal has a box-least-squares signal-to-noise ratio of 17. The transit parameters are then fit jointly with a Gaussian-process stellar variability model, a single stochastically driven damped harmonic oscillator, using the MISTTBORN transit fitting code.","core_discovery":"The paper's central claim is that TOI-2076 hosts a fourth transiting planet, TOI-2076 e, with radius $1.355^{+0.101}_{-0.098}\\,R_\\oplus$, orbital period $3.0223445$ days, and an equilibrium temperature near $1138\\,\\mathrm{K}$. The planet was found only after re-extracting the TESS light curves with custom systematics corrections and running the Notch transit-search pipeline; it is not detectable at sufficient significance in the standard PDCSAP or SAP light curves. False-positive checks, including a TRICERATOPS false-positive probability of about $10^{-5}$, companion-contrast limits, and consistency of the folded signal across sectors spanning four years, lead the authors to conclude that TOI-2076 e is a real planet. The same analysis revises the age of the parent association Crius 224, which includes TOI-2076 and the co-moving system TOI-1807, to $210\\pm20$ Myr, a more precise value than earlier estimates.","pith_inferences":["If small inner planets are systematically missed in young systems, the apparent age-related intra-system uniformity may be largely a selection effect; this paper hints at that possibility but does not prove it.","An independent re-reduction of the same TESS pixels with a different detrending scheme, one that does not use the same basis-spline and PDC co-trending vectors, would provide a direct check on whether the 3.02-day signal is astrophysical.","The revised younger age of 210 Myr, relative to some earlier estimates, would imply less time for photoevaporation and mass loss, which could change inferred formation and evolution histories for all four planets.","If TOI-2076 e is included in dynamical fits, the predicted transit-timing variations of the outer planets may shift enough to be testable with the existing TESS sectors or with future observations."],"forward_implications":["TOI-2076 becomes one of the few young multi-planet systems known to contain a small inner planet, and the new planet pushes the system out of the radius and period uniformity seen in mature Kepler multi-planet systems.","The updated age of 210 ± 20 Myr applies to both TOI-2076 and TOI-1807, sharpening the interpretation of their JWST transmission spectroscopy and of the system's transit-timing variation measurements.","Existing TTV and atmospheric analyses of the three outer planets must account for the gravitational influence of the new 3-day planet, since it was previously missing from dynamical models of the system.","A candidate signal near 6.25 days, if confirmed by future data, would complete a 2:1-5:3-2:1-5:3 resonance chain in the system; the paper does not claim this candidate is a confirmed planet.","The demonstration that custom light-curve extraction can reveal planets invisible in the standard PDCSAP data motivates revisiting other known young transiting systems with the same approach."],"supporting_citations":[{"why":"Discovered the first three TOI-2076 planets and provided the imaging contrast curves and initial age estimate that this work builds on and updates.","marker":"Hedges et al. 2021"},{"why":"Reported transit-timing variations in the outer planets and an older system age; the new inner planet must be consistent with those timing data.","marker":"Osborn et al. 2022"},{"why":"Gathered more than 300 spectra over about three years, ruling out close companions and providing an independent age estimate used for comparison.","marker":"Damasso et al. 2024"},{"why":"Supplied the custom light-curve extraction strategy, using a basis spline, quaternion co-trending, and PDC co-trending vectors, that makes the 3-day transit detectable.","marker":"Vanderburg et al. 2019"},{"why":"Introduced the Notch and LOCoR transit-search approach that the paper uses to find the 3.02-day signal.","marker":"Rizzuto et al. 2017"},{"why":"Provided the adopted stellar radius, mass, effective temperature, and metallicity used in the transit parameter derivation.","marker":"MacDougall et al. 2023"},{"why":"Provided the gyro-interp model used to turn measured rotation periods into the gyrochronology age estimate.","marker":"Bouma et al. 2023"},{"why":"Contributed the original Crius 224 membership list that the paper combines with FriendFinder and GAPS members to build the age-analysis sample.","marker":"Moranta et al. 2022"},{"why":"Supplied lithium equivalent widths and the GAPS survey membership list used for the lithium-sequence age and membership selection.","marker":"Nardiello et al. 2022"}],"fun_headline_variants":["TOI-2076 gains a fourth planet: a 3-day super-Earth","New inner super-Earth detected in TOI-2076","3-day super-Earth found in young system TOI-2076","TESS reprocessing uncovers compact planet in TOI-2076","Age of TOI-2076 revised to 210 Myr with new discovery"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The 3.02-day transit signal is visible only in the authors' custom-detrended TESS light curve; if that detrending itself created a transit-shaped signal at this period, TOI-2076 e would not be real.","fun_headline_variants_meta":{"raw":{"variants":["TOI-2076 gains a fourth planet: a 3-day super-Earth","New inner super-Earth detected in TOI-2076","3-day super-Earth found in young system TOI-2076","TESS reprocessing uncovers compact planet in TOI-2076","Age of TOI-2076 revised to 210 Myr with new discovery"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000262,"raw_usage":{"total_tokens":1612,"prompt_tokens":973,"completion_tokens":639,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":589,"completion_tokens_details":{"reasoning_tokens":540}},"tokens_in":589,"tokens_out":639,"duration_ms":5960,"temperature":1.0,"reasoning_tokens":540,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-15T22:44:49.736736+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Re-reduce the raw TESS pixel data for TOI-2076 with an independent detrending method that does not use the same basis-spline, quaternion, and PDC co-trending vectors, then check whether a 3.0223445-day transit of roughly 1.6% depth persists coherently across Sectors 16, 23, 50, and 77; alternatively, observe the next predicted transits with ground-based photometry or new TESS sectors.","supporting_citations":[{"cited_title":"2024, , 690, A235, 10.1051/0004-6361/202450366","cited_arxiv_id":null,"evidence_quote":"Gathered more than 300 spectra over about three years, ruling out close companions and providing an independent age estimate used for comparison."}],"review_version":1}