{"id":"a52f31a8-48af-466a-a3f8-6ef575a7bc82","arxiv_id":"2501.03947","paper_version":2,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":5.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":5,"one_line_summary":"Simulations show massive main-sequence stars can retain up to about 10% of their mass when jets remove their outer envelope, preventing runaway expansion.","lead":"Massive stars can keep from ballooning while swallowing large amounts of new mass, if jets strip away their outer layers. The finding supports ideas that such engorged stars power eruptive events like the Great Eruption of Eta Carinae.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"The ~10% net accretion is enabled by an imposed mass-removal scheme; the paper does not demonstrate that jets can strip the envelope at the required rate, so the central claim is conditional on an untested feedback loop.","rationale":"The reader's weakest assumption and my load-bearing concern coincide: the 1D simulations impose the mass removal that the jets are supposed to provide, and no hydrodynamical simulation verifies that jets can remove the envelope at the required rate. This is not an internal inconsistency; the paper is transparent about the mimicked scheme. However, the headline statement that 'mass removal from the stellar outskirts allows massive stars to accrete up to ~10%' is physically meaningful only if the removal mechanism is realizable. The paper offers supporting evidence that the disk density exceeds the local envelope density (Section 4) and that the accretion energy budget is sufficient on average (Section 5), but these are necessary, not sufficient, conditions for a steady jet-envelope feedback cycle. The numerical experiments themselves are internally coherent, so conditional acceptance is the appropriate verdict. The concrete test would settle whether the imposed scheme can be replaced by a physical jet-driven removal prescription.","tokens_in":12690,"tokens_out":3005,"duration_ms":32480,"concrete_test":"Run a 2D/3D hydrodynamical simulation of an inflated massive star (R = 1.3 R0, using the density profiles from Fig. 4) with a jet source at r ~ R0 injecting bipolar jets with power L_j = eta Mdot_acc v_esc^2/2 for Mdot_acc ~ 1e-2 Msun/yr. Measure the envelope mass-loss rate and the stellar radius versus time. If the mass-loss rate is less than ~1e-2 Msun/yr or the radius exceeds 1.3 R0 before the envelope is stripped, the central claim fails. As a minimal 1D proxy, replace the imposed removal in MESA with Mdot_rem = 2 eta Mdot_acc, binding-energy-limited by the local escape speed, and check whether R remains bounded.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The central claim is that mass removal from the outskirts lets massive MS stars accrete ~10% of their mass while staying within R <= 1.3 R0. In the 1D model, this constraint is imposed by construction: Section 2 stops accretion when R reaches Radd = kR R0 and then removes mass at a fixed rate until R returns to R0. Thus the radius bound is a boundary condition, not an output, and the net accreted mass is determined by the chosen removal rate and switching radii. The paper's physical justification for this removal is (i) a static density comparison showing the disk is denser than the outer envelope (Section 4, eq. 2) and (ii) an energy bookkeeping argument (Section 5, eq. 5). Neither demonstrates that a jet launched from a disk embedded in the inflated envelope can unbind the outer layers at ~1e-2 Msun/yr, nor that the disk survives the inflow and the jet-envelope interaction. If the jets are less efficient than assumed, the star expands and the ~10% net accretion is not achieved. The authors are explicit about this assumption, so the result is a proof-of-concept conditional on an untested feedback loop.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"This paper uses the one-dimensional stellar evolution code MESA to simulate rapid mass accretion onto 30, 60, and 80 M_sun main-sequence stars under a 'jetted-mass-removal accretion' scenario. In the model, mass is added at 1.5e-2 M_sun/yr with accretion energy deposited in the outer 10% by radius; when the stellar radius reaches k_R R_0 (k_R = 1.17 or 1.3), mass addition is stopped and mass is removed at 1e-2 M_sun/yr until the radius returns to R_0. The reported result is that the stars reach an asymptotic net mass increase of up to about 10% (Table 1) while the final radius returns to R_0. The paper also compares the density of an alpha-disk to the outer envelope density (Section 4) and estimates the removed-to-accreted mass ratio and ejecta velocity (Section 5), arguing that the scenario is relevant to ILOTs, grazing envelope evolution, and the Great Eruption of Eta Carinae.","tokens_in":12994,"tokens_out":5943,"duration_ms":57292,"significance":"If the assumed jet-driven removal of the outer envelope is physically realizable, the scenario would provide a mechanism for massive main-sequence stars to accrete substantial mass at high rates without runaway expansion, which is relevant to several classes of eruptive transients. The MESA models are internally consistent and the paper includes a useful parameter sweep over initial mass, k_R, and eta_acc, with quantitative results in Table 1 and Figures 1-5. The paper is transparent about its central assumption: the jets that remove the envelope are mimicked by imposed mass removal rather than modeled. The main value is as a proof-of-concept; the physical feasibility of the feedback loop remains to be demonstrated.","major_comments":[{"comment":"The radius bound is imposed by construction: mass addition stops when R reaches Radd = k_R R_0 and removal continues until R returns to R_0. Consequently, the statement in Section 3 that the star accretes mass 'without an increase in their final stellar radius' is not an emergent result of the physics; it is a boundary condition of the numerical scheme. The nontrivial output is the asymptotic accreted mass for this protocol, and the paper should state this explicitly and avoid presenting the radius constraint as a finding. It would strengthen the paper to vary the removal efficiency (e.g., Mdot_rem) and show how the net accreted mass degrades if removal is slower than assumed.","section":"Section 2, Eq. (1)"},{"comment":"The physical mechanism for the imposed mass removal is not demonstrated. The density comparison in Section 4 (Eq. 2 vs. envelope density) establishes only a static necessary condition for a disk to exist inside the inflated envelope; it does not show that the disk can survive the inflow and jet-envelope interaction, nor that the jets can unbind the outer layers at the imposed Mdot_rem ~ 1e-2 M_sun/yr. The energy argument in Section 5 assumes that a fraction zeta ~ 1 of the accretion energy is converted into ejection of the removed mass, but no model or simulation of this coupling is presented. This is the load-bearing assumption of the paper, and it should be labeled as such throughout, with a concrete feasibility estimate or an explicit statement that the result is conditional on this assumption.","section":"Sections 4-5"},{"comment":"The accretion energy is deposited uniformly per unit mass in the outer 0.1 by radius. This radial distribution is not derived from a physical model of where the accreted gas shocks or where the jet energy is thermalized, and it directly controls the expansion that triggers the mass-removal phase. The paper varies eta_acc but not the deposition zone or its profile; a test of the sensitivity to this choice (or a physical justification) is needed before the ~10% result can be considered robust.","section":"Section 2, energy deposition"}],"minor_comments":[{"comment":"In the description of the mass-removal part, the rate is written as Mdot_add = -1e-2; this should be Mdot_rem to avoid confusion with the addition rate.","section":"Section 2"},{"comment":"The explanation that the thickness of each curve is not the line width but results from dense pulse spacing is confusing; consider plotting the envelope of the mass range or sampled pulse extrema.","section":"Figure 2 caption"},{"comment":"The derivation of Eq. (5) is too terse: please define q_ej and zeta in the same paragraph and state clearly that the removed mass is assumed to be ejected with no net energy contribution.","section":"Section 5, Eq. (5)"},{"comment":"Macc,f is called the asymptotic accreted mass, but no criterion for asymptotic convergence is given; please state the tolerance or the time at which the value is read.","section":"Table 1"},{"comment":"The phrase 'the outer parts have very high entropy' should refer to Figure 3 and specify that this refers to the newly accreted outer envelope.","section":"Section 3"}],"recommendation":"major_revision","confidential_remarks":"The paper's central claim is carefully hedged in the abstract ('We assume that these jets remove the outer layers'), but the discussion and conclusion present the scenario as 'on solid ground.' My main concern is that the imposed mass removal makes the radius constraint tautological; the paper would be stronger if it were framed as a parametric study of stellar response under a prescribed removal protocol. I recommend major revision, not rejection, because the MESA calculations are internally consistent and the assumption is explicit; with reframing and sensitivity tests this could be publishable."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Dear colleague,\n\nThe headline: this is a careful proof-of-concept, not a demonstration. The paper shows that if you impose mass removal whenever the star expands beyond a threshold, a massive main-sequence star can retain about 10% of its mass. That 'if' is doing the work—the removal is prescribed, not sourced from a physical jet model. But the authors are unusually honest about this, and the MESA runs are internally consistent.\n\nWhat's new: Bear & Soker 2025 did the same idea with fixed mass steps and accreted less than 1% of the stellar mass. This version switches to a radius-triggered scheme and finds asymptotic mass growth up to ~10% for k_R = 1.3. It also adds a disk-density comparison (Eq. 2) that suggests the disk can survive inside the inflated envelope, and an energy budget for the ejected mass (Eq. 5). The entropy argument—that the accreted outer layers are high-entropy and removing them lets the star contract—is a genuine physical insight.\n\nThe soft spots are the ones you'd expect. The radius bound is a boundary condition, so the 'no expansion' result is built into the control flow. The disk-survival argument is a static density comparison, not a hydrodynamical simulation; the jets' ability to strip the envelope at ~1e-2 M_sun/yr is assumed. The energy deposition in the outer 10% by radius is crude, though the results are insensitive to eta_acc, which is reassuring. The discussion overstates when it says the scenario is on 'solid ground'—it's on plausible ground.\n\nIf the jets are less efficient than assumed, the star expands and the 10% disappears. The paper doesn't prove the jets work. But it frames the question sharply: what is the maximum net accretion when mass is removed? That's a legitimate proof-of-concept.\n\nI'd send it to review. A referee can push for a clearer statement that the result is conditional on an untested feedback loop and for a more careful treatment of the disk survival. The authors have already done the honest part in the abstract. The paper will be useful to people modeling ILOTs, luminous red novae, and the Eta Carinae Great Eruption.\n\nBest, [Your name]","headline":"Proof-of-concept for jet-regulated accretion: the ~10% mass gain is conditional on an imposed mass-removal scheme, not a demonstrated jet feedback loop.","tokens_in":13496,"tokens_out":2976,"would_cite":false,"duration_ms":27764,"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":"Main-sequence stars can net-accrete roughly 10% of their mass without expanding, if jets strip the outer envelope.","keywords":["massive main-sequence stars","mass accretion","stellar jets","mass removal","stellar expansion","intermediate-luminosity optical transients","Eta Carinae","MESA stellar evolution"],"falsifier":"Run a three-dimensional hydrodynamical simulation of an accretion disk embedded in an inflated main-sequence envelope, with a jet duty cycle and power matching the 1D removal rate; if the jets cannot expel the outer ~10% of the radius before the envelope engulfs the disk, or if the disk is destroyed by the inflated envelope, the ~10% net accretion would not occur.","tokens_in":12518,"feed_emoji":"⭐","tokens_out":5244,"duration_ms":45614,"temperature":0.7,"pith_summary":"This paper argues that massive main-sequence stars can keep their radius small while accreting mass at high rates, provided that jets launched by an accretion disk continuously remove the star's outer envelope. Using one-dimensional stellar-evolution simulations with alternating mass-addition and mass-removal phases, the authors show that stars of 30, 60, and 80 solar masses can each net-accrete about 10% of their initial mass before the process saturates, without permanently inflating. The result matters because jet-powered models of energetic transients such as luminous red novae and the Great Eruption of Eta Carinae require a companion star to swallow a few solar masses while staying deep enough in its gravitational potential to launch energetic jets.","feed_headline":"Jets let massive stars swallow 10 percent extra mass","feed_subtitle":"Simulations show main-sequence stars keep their radius while accreting if jets strip the outer envelope.","key_machinery":"The mechanism is a two-part accretion pulse in the MESA stellar-evolution code: add mass at $1.5\\times10^{-2}\\,M_\\odot\\,\\mathrm{yr}^{-1}$ together with a fraction $\\eta_{\\rm acc}$ of the accretion energy into the outer 10% by radius until the star expands to $R_{\\rm add} = k_R R_0$, then remove mass at $1\\times10^{-2}\\,M_\\odot\\,\\mathrm{yr}^{-1}$ until the star contracts back to $R_0$. The high-entropy, loosely bound outer layers created by energy deposition are exactly the layers removed, so the star keeps a deep potential well. A scaled density estimate for a Shakura-Sunyaev disk shows the disk is denser than the inflated envelope's outer layers, supporting the assumption that the disk survives and can launch jets there.","core_discovery":"The central claim is that imposing a radius cap—allowing the star to swell to only $k_R = 1.3$ times its initial radius between mass-addition episodes—lets a $30$–$80\\,M_\\odot$ main-sequence star asymptotically accumulate up to about 10% of its mass, because the high-entropy outer layers added during accretion are stripped away before they force runaway expansion. The accumulated mass grows with the allowed radius cap and with lower stellar mass, while the energy-injection efficiency $\\eta_{\\rm acc}$ has little effect. Without the removal phase, adding mass even without extra energy inflates the star, and constant-rate accretion without removal leads to unstable expansion, as earlier work found.","pith_inferences":["If the mechanism works, the accreting star acts mainly as a mass processor: for every solar mass it keeps, it must eject several through jets (qej up to ~30 at early times for the 30-solar-mass model), so the inflowing envelope gas is recycled rather than accumulated.","The imposed radius cap resembles tidal truncation by an orbiting companion; real systems without such truncation may not achieve the same net accretion, so applying this scenario to isolated stars or wide binaries is not automatic.","Because the removal targets high-entropy regions, other removal agents such as line-driven winds or a common-envelope interaction might also prevent radius inflation; the jet is one concrete realization.","A direct observational test could search ILOT light curves and ejecta for the predicted low terminal velocities (well below escape velocity) and large ejected-to-accreted mass ratios."],"forward_implications":["A 30–80 solar-mass main-sequence star can asymptotically net-accrete about 10% of its initial mass without a final radius increase when its radius is capped at 1.3 R0.","Lower-mass stars and larger allowed radius caps yield larger fractional mass growth and higher net accretion rates.","The accretion disk's density exceeds the inflated envelope's outer-layer density by roughly an order of magnitude, so jets can plausibly be launched inside the envelope.","The scenario can supply the ~4 solar masses accreted by the proposed companion during Eta Carinae's Great Eruption, and power ILOTs and luminous red novae.","The ejected mass is several times the net accreted mass, so the ejecta's average terminal velocity is well below the stellar escape velocity."],"supporting_citations":[{"why":"Introduces the jetted-mass-removal accretion scenario and demonstrates it for <1% mass growth; this study extends it to ~10%.","marker":"Bear & Soker 2025"},{"why":"Shows main-sequence stars accreting at constant rates without mass removal expand unstably, providing the baseline this mechanism must avoid.","marker":"Schürrmann & Langer 2024"},{"why":"Supplies the scaled accretion-disk density equation (their equation 5.49) used to argue the disk survives inside the inflated envelope.","marker":"Frank et al. 2002"},{"why":"Sets the required companion accretion of about 4 solar masses during the Great Eruption of Eta Carinae, the observational target the scenario addresses.","marker":"Kashi & Soker 2016b"},{"why":"Provides the MESA version (24.03.1) used for the stellar models, the tool that carries the simulations.","marker":"Jermyn et al. 2023"}],"fun_headline_variants":["Jets strip envelopes so massive stars bulk up","Jets prevent expansion in accreting massive stars","Envelope stripping by jets enables high mass accretion","Massive stars can swallow 10% more mass with jet stripping","Jets strip envelope to let massive stars accrete up to 10% mass"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The scenario assumes the jets actually strip the outer envelope at the rate and in the manner imposed by the 1D mass-removal prescription; this jet–envelope interaction is never simulated in three dimensions.","fun_headline_variants_meta":{"raw":{"variants":["Jets strip envelopes so massive stars bulk up","Jets prevent expansion in accreting massive stars","Envelope stripping by jets enables high mass accretion","Massive stars can swallow 10% more mass with jet stripping","Jets strip envelope to let massive stars accrete up to 10% mass"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000995,"raw_usage":{"total_tokens":4219,"prompt_tokens":954,"completion_tokens":3265,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":570,"completion_tokens_details":{"reasoning_tokens":3191}},"tokens_in":570,"tokens_out":3265,"duration_ms":21499,"temperature":1.0,"reasoning_tokens":3191,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-10T21:43:17.489108+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Run a three-dimensional hydrodynamical simulation of an accretion disk embedded in an inflated main-sequence envelope, with a jet duty cycle and power matching the 1D removal rate; if the jets cannot expel the outer ~10% of the radius before the envelope engulfs the disk, or if the disk is destroyed by the inflated envelope, the ~10% net accretion would not occur.","supporting_citations":[{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Supplies the scaled accretion-disk density equation (their equation 5.49) used to argue the disk survives inside the inflated envelope."},{"cited_title":"S., Bauer, E","cited_arxiv_id":null,"evidence_quote":"Provides the MESA version (24.03.1) used for the stellar models, the tool that carries the simulations."}],"review_version":1}