{"id":"00c3214a-568e-4a5f-96fb-d8481b3ca948","arxiv_id":"2506.20019","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":4.0,"correctness_risk":"low","formal_verification":"none","parameter_count":9,"one_line_summary":"TOI-4465 b is a confirmed 5.89 Jupiter-mass, 1.25 Jupiter-radius transiting giant planet on a 101.94-day eccentric orbit around a G dwarf, validated from a single TESS transit plus radial velocities and a globally observed second transit.","lead":"Astronomers confirm a giant planet, TOI-4465 b, that orbits a Sun-like star every 102 days after spotting it only once in TESS satellite data. A worldwide network of telescopes and 24 citizen scientists caught a second transit, pinning down the planet's size, mass and orbit.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Post hoc exclusion of CORALIE RVs is not supported by their quoted errors; a refit including those six points is needed to certify the orbital parameters.","rationale":"The reader's stated weakest assumption is the adopted stellar radius and mass, but in my reading the more load-bearing point is the post hoc exclusion of CORALIE RVs, which directly affects the orbital parameters and therefore the mass. The paper explicitly describes the exclusion and gives a reason that contradicts its own Table 7, so this is an internal inconsistency worth testing rather than an external disagreement. If the refit with CORALIE leaves P, K, and e within ~1 sigma, the central claim of a confirmed 101.94-day, 5.89 MJ planet remains strong; if not, the parameters as published are not robust. I do not see a reason to reject the paper: the single TESS transit, the multi-site ground-based coverage, the NEOSSat transit, high-resolution imaging, and the coherent RV signal from three instruments independently point to the same system. The stellar-radius concern is real but secondary: it rescales Rp and density, not the confirmation or the orbital solution. The CORALIE concern supports the reader's CONDITIONAL verdict rather than moving it.","tokens_in":34914,"tokens_out":11359,"duration_ms":133326,"concrete_test":"Re-run the juliet global fit with the six CORALIE RVs added, giving them a free systemic offset and free jitter, and compare posterior medians and 68% intervals for P, K, e, and omega plus the Bayesian log evidence (Delta ln Z) against the published no-CORALIE fit. If the parameters shift by less than ~1 sigma and Delta ln Z does not strongly favor exclusion, the headline solution is robust; if they shift by more than that, the reported values are selection-dependent and the paper must present both fits.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The central claim (P, K, e, and hence Mp) rests on a joint RV fit from which the six CORALIE RVs were excluded. Section 3.2.4 and Section 4.2 state the exclusion was because the CORALIE data 'increased parameter uncertainties, and added noise without enhancing model precision' and had 'large errorbars.' This rationale is not consistent with Table 7: the quoted CORALIE uncertainties are 6.7–13.9 m/s, comparable to APF and smaller than most TRES uncertainties (17–29 m/s), yet TRES data are kept. Because data exclusion decisions made after seeing the fit can bias period, eccentricity, and semi-amplitude estimates, the orbital parameters currently quoted are not auditable. If the six CORALIE points are in tension with the adopted model, their removal could conceal a systematic problem or a genuine mismatch; if they are consistent, their removal is unnecessary and should be documented with a quantitative comparison. Without this check, the confirmation is conditional on an unexplained selection step.","agreement_with_reader":"partial"},"referee_report":{"model":"deepseek-v4-flash","summary":"The manuscript reports the discovery and confirmation of TOI-4465 b, a transiting giant planet first detected as a single TESS Sector 40 transit. The authors combine TESS and ground-based photometry (LCOGT, NGTS, Unistellar/eVscope, and NEOSSat) with radial velocities from APF, CHIRON, and TRES in a joint juliet fit, yielding P = 101.94054 d, K = 277.19 m/s, e = 0.24, Rp = 1.25 RJ, Mp = 5.89 MJ, and a bulk density of 3.73 g/cm^3. The RV-determined period was used to predict and then observe a second transit from multiple sites, providing an independent confirmation of the ephemeris. The paper also discusses the planet's population context, atmospheric characterization prospects, heavy-element enrichment, and obliquity measurement.","tokens_in":35120,"tokens_out":9407,"duration_ms":95622,"significance":"If accepted, this is a valuable addition to the small sample of long-period transiting giant planets: TOI-4465 b is claimed to have the largest radius among transiting giants with P > 100 days and is among the best long-period targets for emission spectroscopy. The detection strategy is strong in an important respect: the RV period was fit independently of the later ground-based transit, and that transit was predicted from the RV period and then observed, rather than being used circularly in the period solution. The detailed data tables and the use of published structure models for the heavy-element interpretation are additional strengths. The main caveats are that the derived planetary properties scale directly with the SED-based stellar radius and mass, and the exclusion of the CORALIE RVs from the final fit is not yet demonstrated to be innocuous.","major_comments":[{"comment":"The exclusion of the six CORALIE RVs from the final fit is not adequately justified, and because the final orbital parameters are load-bearing for the paper's central claim, this needs to be fixed. The text in Sections 3.2.4 and 4.2 states that the CORALIE data have 'large errorbars' and 'added noise without enhancing model precision,' but Table 7 lists quoted uncertainties of 6.5-14.7 m/s, which are comparable to APF and CHIRON and smaller than most TRES uncertainties (17.5-29.4 m/s; Table 6). The manuscript reports that the data were modeled with and without CORALIE, but gives no quantitative comparison of the two fits. If the six points are consistent with the adopted solution, they should be retained or their removal should be justified by a numerical model comparison; if they are in tension, the tension must be diagnosed rather than hidden by exclusion. Please report the CORALIE-inclusive values of P, K, e, and omega (with a fitted CORALIE offset), the change in log evidence or chi-square, and a brief residual analysis for the six points.","section":"Sections 3.2.4 and 4.2; Tables 6 and 7"}],"minor_comments":[{"comment":"Three APF epochs (2459817.77572, 2459835.70532, and 2459850.70414) appear twice with identical RVs and uncertainties; please clarify whether these are genuine duplicate exposures or a copying error in the table.","section":"Section 3.2.1, Table 4"},{"comment":"The final Hazelwood Observatory row lists start and end times of 10414.1959-10414.2601, which is inconsistent with the BTJD-2450000 convention used for the other rows and with the 2022 campaign dates; this is presumably a typo and should be corrected.","section":"Table 8"},{"comment":"The heavy-element enrichment calculation follows Thorngren et al. (2016), a framework noted to be calibrated for planets with P < 100 days, while TOI-4465 b has P = 101.94 days; the text should add a sentence quantifying the expected extrapolation uncertainty.","section":"Section 5.3"},{"comment":"The reduced chi-squared of 1.5 for the SED fit would be more informative with the number of degrees of freedom, since a reduced chi-squared near 1.5 can indicate either an acceptable fit or underestimated photometric uncertainties depending on the number of constraints.","section":"Section 2.1"},{"comment":"The corner plot of the posterior distribution is not referenced in the main text; please add a pointer in Section 4 so that readers know the full posterior covariances are available.","section":"Section A1 / Figure A1"}],"recommendation":"major_revision","confidential_remarks":"The discovery appears real and the confirmation strategy is sound. My recommendation rests on a single substantive issue: the CORALIE exclusion must be demonstrated to be inconsequential. If the authors provide the inclusive fit and it leaves P, K, e, and hence Mp unchanged within uncertainties, I would support acceptance. I would also encourage the editor to ask for a residual periodogram of the RVs, though I have not made that a major point."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Colleague,\n\nQuick take: this is a well-executed confirmation of a genuinely new long-period transiting giant planet, TOI-4465 b. The detection chain is independent and the planet is almost certainly real. The main flaw is a transparency gap: the CORALIE RVs were excluded from the final fit, and the stated reason doesn't hold up against the quoted errors. That needs fixing in revision, not redoing the analysis.\n\nWhat's actually new: the paper confirms a single TESS transit into a full planetary solution—P ≈ 101.94 d, K ≈ 277 m/s, e ≈ 0.24, R ≈ 1.25 RJ, M ≈ 5.9 MJ—using APF/CHIRON/TRES RVs and then a globally predicted second transit (LCOGT, NGTS, eVscope citizen science, NEOSSat). The period is set by RVs independently of the photometry, and the ground-based transit was predicted from that period and observed. That's a solid mutually-corroborating chain. The stellar characterization is thorough: SED+Gaia radius/mass, speckle and AO imaging to rule out companions. The heavy-element and atmospheric prospects discussion is reasonable but incremental.\n\nWhere it's soft: the exclusion of the six CORALIE points. Sections 3.2.4 and 4.2 say the data were excluded because of 'large errorbars' that 'added noise' and increased uncertainties. But Table 7 shows CORALIE errors of 6.7–13.9 m/s—actually comparable to APF and clearly smaller than most TRES errors (17–29 m/s). TRES is retained. The paper states they fit with and without CORALIE, but doesn't show that comparison. That's exactly the kind of post-hoc selection a referee needs to see quantified. I don't think it's fatal—the period, K, and e are pinned by many APF points, and the planet would almost certainly survive a refit—but as written it is a legitimate audit gap. Show the alternative fit: parameter shifts, maybe a phase-folded plot of CORALIE against the model. Also minor: a few tables have duplicate rows (APF/CHIRON timestamps, and the Hazelwood date looks garbled), and no code or derived data products are shipped, which makes independent replication much harder.\n\nThe reader's conditional verdict lands well; I'd actually go a touch more positive on the paper's value as a demographic data point, but the conditional is right.\n\nBottom line: send it to peer review. A competent referee should request the CORALIE comparison and a few typo fixes, and then it's publishable in a solid journal. Worth reading for anyone doing single-transit follow-up.","headline":"Solid incremental confirmation of a new long-period giant planet; the main issue is the unexplained exclusion of CORALIE RVs, which a referee should ask to see quantified.","tokens_in":36105,"tokens_out":2623,"would_cite":false,"duration_ms":28621,"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-4465 b is a confirmed massive, dense, temperate giant planet on a 101.94-day eccentric orbit, established from a single TESS transit plus radial velocities and a globally observed second transit.","keywords":["exoplanets","single-transit events","long-period giant planets","warm Jupiters","radial velocity","transit photometry","planetary system formation","TOI-4465 b"],"falsifier":"Measure the stellar radius independently, for example with asteroseismology or long-baseline interferometry, and compare it with $1.014 \\pm 0.041\\,R_\\odot$; a disagreement larger than about 8% (roughly 2 $\\sigma$) would rescale the planetary radius, density, and heavy-element mass enough to shift several of the paper's conclusions.","tokens_in":34687,"feed_emoji":"🪐","tokens_out":10309,"duration_ms":96480,"temperature":0.7,"pith_summary":"The paper establishes that TOI-4465 b is a real transiting giant planet: a $5.89 \\pm 0.26$ Jupiter-mass, $1.25^{+0.08}_{-0.07}$ Jupiter-radius world on a $101.94054$ day, mildly eccentric orbit around a G dwarf at about 122 pc. The case matters because the planet was uncovered as a single transit in TESS data, and long-period planets leave very few such events; the paper shows that radial velocities can solve the orbit and a coordinated ground-based campaign can catch the next transit, turning a one-off detection into a fully characterized system. The result adds a relatively dense ($3.73 \\pm 0.53$ g/cm$^3$) and temperate (375--478 K) giant to a sparse region of mass--radius--period space, and identifies it as one of the best long-period planets for atmospheric emission spectroscopy.","feed_headline":"A 102-day giant planet confirmed from a single TESS transit","feed_subtitle":"Radial velocities and a global ground-based campaign caught the second transit, pinning down a dense, temperate 5.9-Jupiter-mass world.","key_machinery":"The load-bearing mechanism is the pairing of a single space-based transit with dense radial-velocity monitoring: the RVs set the orbital period, eccentricity, and mass, and that timing prediction then guided a global photometric campaign to catch the next transit, confirming the ephemeris. The machinery includes a joint fit of all photometry and RVs, with the stellar density left free and the planet radius and semimajor axis tied to Kepler's third law, plus stellar limb-darkening coefficients computed from model atmospheres. The long transit duration (about 12 hours) is what makes worldwide longitudinal coverage essential and practical, and the lack of detected stellar companions from high-resolution imaging validates the single-star dilution assumption.","core_discovery":"The central claim is that TOI-4465 b is a confirmed transiting giant with orbital period $P = 101.94054^{+0.00040}_{-0.00036}$ d, radial-velocity semi-amplitude $K = 277.19^{+2.37}_{-1.90}$ m/s, eccentricity $e = 0.24 \\pm 0.01$, radius $R_p = 1.25^{+0.08}_{-0.07}\\,R_J$, and mass $M_p = 5.89 \\pm 0.26\\,M_J$. A single TESS transit in Sector 40 triggered the search; radial velocities from three spectrographs determined the period and amplitude, and a worldwide photometric campaign caught the roughly 12-hour second transit, confirming the ephemeris. From the joint fit the paper derives a bulk density of $3.73 \\pm 0.53$ g/cm$^3$ and equilibrium temperatures of 375 K at apastron and 478 K at periastron. Comparing the planet to giant-planet structure models, it finds a heavy-element mass fraction $Z_p = 0.091 \\pm 0.017$, or about $171 \\pm 32$ Earth masses of heavy elements, roughly $7.5 \\pm 1.4$ times the host star's heavy-element fraction. The paper further argues that TOI-4465 b is the largest-radius giant with $P > 100$ days, one of the most massive such planets, and a strong target for emission spectroscopy and obliquity measurement.","pith_inferences":["Extension: If the same single-transit-plus-RV-plus-second-transit recipe works at scale, the census of planets beyond 100-day periods could grow quickly, and population comparisons between hot, warm, and cold giants would become statistically meaningful.","Extension: The unusually high density for a 5.9-Jupiter-mass planet at this period suggests modest envelope inflation; measuring the planet's infrared emission could test whether tidal or stellar irradiation effects are truly negligible at these separations.","Extension: A third transit observed at the predicted time would shrink the period uncertainty further and open a search for transit-timing variations that could reveal an outer companion in the system.","Extension: The host star's apparently super-solar magnesium abundance, if confirmed by higher-resolution abundance work, could point to a chemical environment that favored efficient solid accretion, offering a testable link to the planet's heavy-element content."],"forward_implications":["Single-transit TESS candidates can be promoted to precisely characterized planets when the RV-anchored ephemeris is followed by a coordinated second-transit campaign, so the confirmation path demonstrated here should be reusable for many similar candidates.","TOI-4465 b becomes a benchmark giant planet at $P > 100$ days with radius, mass, and density all measured to better than 10%, sharpening the mass--radius relation for non-inflated, temperate giants.","With the third-highest emission spectroscopy metric among confirmed long-period giants, TOI-4465 b is one of the best available targets for probing cool-giant chemistry such as CO/CH$_4$ and N$_2$/NH$_3$ disequilibrium.","Its heavy-element enrichment of $Z_p/Z_* = 7.5 \\pm 1.4$ is consistent with late-stage accretion of icy planetesimals, adding a high-mass, low-host-metallicity data point to tests of core-accretion versus disk-instability formation.","The predicted Rossiter--McLaughlin amplitude of up to about 42 m/s makes TOI-4465 b a viable candidate for measuring the obliquity of a long-period planet, which would test disk versus dynamical migration histories."],"supporting_citations":[{"why":"Describes the Quick-Look Pipeline that first flagged the single-transit event in TESS Sector 40.","marker":"Huang et al. 2020"},{"why":"Documents the single-transit search and light-curve extraction used to alert TOI-4465.01.","marker":"Kunimoto et al. 2021"},{"why":"Supplies the spectral-energy-distribution method used to derive the adopted stellar radius and mass.","marker":"Stassun & Torres (2016)"},{"why":"Provides the joint transit-plus-RV fitting framework used for the global model.","marker":"Espinoza et al. (2019)"},{"why":"Gives the limb-darkening parametrization used to sample the transit light curves.","marker":"Kipping (2013)"},{"why":"Provides the giant-planet structure models and mass-metallicity relation used to estimate heavy-element content.","marker":"Thorngren et al. (2016)"},{"why":"Defines the transmission and emission spectroscopy metrics used to rank TOI-4465 b as an atmospheric target.","marker":"Kempton et al. (2018)"}],"fun_headline_variants":["5.9-Jupiter-mass planet confirmed from one TESS transit","Citizen science catches second transit of 102-day giant","Dense and temperate: giant planet with 171 Earth masses of metals","Single flash, 102-day orbit: a giant planet's confirmation"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The adopted stellar radius and mass—$R_* = 1.014 \\pm 0.041\\,R_\\odot$ and $M_* = 0.93 \\pm 0.06\\,M_\\odot$, from the spectral-energy-distribution plus Gaia analysis—must be correct, because every derived planetary radius, mass, density, and heavy-element mass rescales directly from those values even though the transit and radial-velocity detection themselves would survive.","fun_headline_variants_meta":{"raw":{"variants":["5.9-Jupiter-mass planet confirmed from one TESS transit","Citizen science catches second transit of 102-day giant","Dense and temperate: giant planet with 171 Earth masses of metals","Single flash, 102-day orbit: a giant planet's confirmation"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000815,"raw_usage":{"total_tokens":3725,"prompt_tokens":1254,"completion_tokens":2471,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":870,"completion_tokens_details":{"reasoning_tokens":2397}},"tokens_in":870,"tokens_out":2471,"duration_ms":21678,"temperature":1.0,"reasoning_tokens":2397,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-15T18:21:54.124156+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Measure the stellar radius independently, for example with asteroseismology or long-baseline interferometry, and compare it with $1.014 \\pm 0.041\\,R_\\odot$; a disagreement larger than about 8% (roughly 2 $\\sigma$) would rescale the planetary radius, density, and heavy-element mass enough to shift several of the paper's conclusions.","supporting_citations":[],"review_version":2}