pith. sign in

arxiv: 2604.26144 · v1 · submitted 2026-04-28 · 🌌 astro-ph.SR · astro-ph.HE

Evolving Low- and Intermediate-Mass Binaries: Departures from Classical Theory

Lionel Siess This is my paper

Pith reviewed 2026-05-07 14:32 UTC · model grok-4.3

classification 🌌 astro-ph.SR astro-ph.HE
keywords low-mass binariesintermediate-mass binariesbinary star evolutionRoche lobe overflowtidal dissipationorbital eccentricitymass transferwind accretion
0
0 comments X

The pith

Deviations from classical Roche lobe theory arise in eccentric and asynchronously rotating binary stars.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

This review examines the evolution of low- and intermediate-mass binary stars and identifies physical mechanisms that depart from traditional frameworks. The Roche lobe formalism needs revision for eccentric orbits and asynchronous rotation, where standard approximations lose accuracy. Hydrodynamical simulations of wind accretion and advances in tidal dissipation theory update models of mass and angular momentum exchange. Mechanisms such as mass-transfer perturbations and circumbinary disk interactions can sustain or excite orbital eccentricity rather than damp it. Accurate treatment of these effects matters for predicting binary outcomes including compact object formation and observable system properties.

Core claim

The paper argues that classical paradigms of binary star evolution must be updated because the Roche lobe formalism deviates substantially in systems with eccentric orbits and asynchronous rotation. Recent hydrodynamical simulations of wind accretion and progress in tidal dissipation theory alter the description of mass and angular momentum transfer. Processes capable of sustaining or exciting orbital eccentricity, including those induced by mass transfer and circumbinary disks, are identified as important factors that challenge the classical expectation of rapid circularization.

What carries the argument

The Roche lobe formalism reassessed for eccentric orbits and asynchronous rotation, together with hydrodynamical models of wind accretion and tidal dissipation mechanisms that affect orbital eccentricity.

If this is right

  • Mass and angular momentum transfer rates must be recalculated for eccentric and asynchronous configurations.
  • Tidal dissipation models incorporating recent theory will change predicted orbital evolution timescales.
  • Eccentricity can be maintained or increased by mass-transfer perturbations and circumbinary disks.
  • Population synthesis calculations of binary systems require inclusion of these non-classical effects.
  • Observational surveys of eccentric binaries can directly test the revised descriptions of mass transfer.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • These revisions could alter predicted rates of binary systems reaching compact-object stages or producing specific transients.
  • The same mechanisms may help resolve differences between observed eccentricity distributions and classical model outputs.
  • Targeted hydrodynamical runs at particular mass ratios and eccentricities would refine the quantitative impact of the departures.

Load-bearing premise

The review assumes that hydrodynamical simulations of wind accretion and recent advances in tidal dissipation theory accurately capture the dominant physics of mass and angular momentum exchange.

What would settle it

A measurement of mass-transfer rate or circularization timescale in an eccentric, asynchronously rotating low-mass binary that matches classical Roche-lobe predictions rather than hydrodynamical simulation results would test the claimed departures.

Figures

Figures reproduced from arXiv: 2604.26144 by Lionel Siess.

Figure 1
Figure 1. Figure 1: Notations and system geometry. 𝐺 is the center of mass of the binary, which consists of a primary and a secondary star with radii 𝑅1 and 𝑅2, respectively. The inner Lagrangian point, L1, lies along the line connecting the centers of the two stars, which defines the x-axis of the coordinate system. where 𝑃tot is the total pressure including both gas and radiation contributions, and 𝜌 the density. When the s… view at source ↗
Figure 2
Figure 2. Figure 2: The top panel displays the equipotential surfaces passing through view at source ↗
Figure 3
Figure 3. Figure 3: Topology of the Roche equipotentials in the orbital plane as a function view at source ↗
Figure 4
Figure 4. Figure 4: Ballistic trajectories of material escaping the view at source ↗
Figure 5
Figure 5. Figure 5: Two dimensional slice revealing the density structure in the equatorial (left column) and meridional (right column) plane for binary wind interaction in a view at source ↗
Figure 6
Figure 6. Figure 6: Accretion efficiency 𝛽 as a function of the wind-to-orbital velocity ratio for different available prescriptions. Solid lines represent values computed using the empirical relation from Saladino et al. (2019) (Eq. 50) for different mass ratios 𝑞. The dashed lines show the corresponding predictions from the BHL formalism (Eq. 47). The red solid line shows the fit derived by Nagae et al. (2004) for 𝑞 = 1. (2… view at source ↗
Figure 7
Figure 7. Figure 7: Evolution of the eccentricity (top), ratio of spin to orbital angular view at source ↗
Figure 8
Figure 8. Figure 8: Roche lobe overflow mass transfer rate as a function of orbital phase view at source ↗
Figure 9
Figure 9. Figure 9: Evolution in the eccentricity-period diagram of a 2+1 view at source ↗
read the original abstract

This review explores the physical mechanisms driving the evolution of low- and intermediate-mass binary star systems, with particular emphasis on emerging mechanisms that challenge classical paradigms. We begin by describing the principal formation channels and orbital properties of binary systems. A critical reassessment of the Roche lobe formalism is presented, focusing on systems with eccentric orbits and asynchronous rotation, where deviations from traditional approximations become significant. We then review current theoretical models of mass and angular momentum exchange via Roche-lobe overflow, incorporating results from recent hydrodynamical simulations of wind accretion. The review also reports advances in tidal dissipation theory. Finally, we explore mechanisms capable of sustaining or exciting orbital eccentricity, including perturbations induced by mass transfer and interactions with circumbinary disks. These discussions aim to outline underexplored facets of binary evolution, offering new perspectives for theoretical and observational studies.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

0 major / 3 minor

Summary. The manuscript is a review paper exploring the physical mechanisms in the evolution of low- and intermediate-mass binary star systems, with emphasis on departures from classical theory. It covers formation channels and orbital properties, presents a critical reassessment of the Roche lobe formalism for eccentric orbits and asynchronous rotation, reviews mass and angular momentum exchange via Roche-lobe overflow informed by hydrodynamical simulations of wind accretion, discusses advances in tidal dissipation theory, and examines mechanisms for sustaining or exciting orbital eccentricity including mass transfer perturbations and circumbinary disk interactions. The goal is to outline underexplored facets and offer new perspectives for theoretical and observational studies.

Significance. If the synthesis holds, the review is significant as a timely compilation of recent literature challenging classical binary evolution paradigms. It explicitly credits the strength of its discussion to cited hydrodynamical simulations and tidal dissipation advances rather than original derivations, providing a useful roadmap for future work on non-standard Roche-lobe overflow and eccentricity excitation in stellar astrophysics.

minor comments (3)
  1. [Abstract] Abstract: The phrase 'emerging mechanisms' is used without quantifying how many or which specific processes are newly emphasized versus established; a brief enumeration in the abstract would improve clarity for readers scanning the review.
  2. [Mass and Angular Momentum Exchange] The manuscript should include a dedicated section or table summarizing the key cited hydrodynamical simulations (e.g., specific references to wind accretion studies) to allow readers to trace the quantitative inputs to the discussion of mass exchange.
  3. [Roche Lobe Formalism] Notation for orbital parameters (e.g., eccentricity, rotation rates) should be defined consistently at first use, as the review draws from multiple external theories where conventions may differ.

Simulated Author's Rebuttal

0 responses · 0 unresolved

We thank the referee for their positive assessment of the manuscript, accurate summary of its scope, and recommendation for minor revision. We appreciate the recognition that the review provides a timely compilation and useful roadmap for future work on departures from classical binary evolution, particularly the emphasis on hydrodynamical simulations and tidal theory.

Circularity Check

0 steps flagged

No significant circularity; review synthesizes external literature

full rationale

This is a review paper that summarizes existing literature on binary star evolution mechanisms, Roche lobe deviations, hydrodynamical simulations of wind accretion, tidal dissipation, and eccentricity excitation. It presents no original derivations, quantitative predictions, fitted parameters, or first-principles calculations of its own. All load-bearing content is explicitly attributed to cited external hydrodynamical and tidal studies, with no self-definitional loops, fitted inputs renamed as predictions, or load-bearing self-citations that reduce the central claims to internal inputs. The manuscript is therefore self-contained against external benchmarks and exhibits no circularity by the defined criteria.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

This is a review paper; the abstract introduces no new free parameters, axioms, or invented entities. All content rests on cited prior literature.

pith-pipeline@v0.9.0 · 5436 in / 1028 out tokens · 92035 ms · 2026-05-07T14:32:25.035309+00:00 · methodology

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Reference graph

Works this paper leans on

8 extracted references · 8 canonical work pages

  1. [1]

    Herschel Multitiered Extragalactic Survey: clusters of dusty galaxies uncovered by Herschel and Planck

    Sphericalaccretion: Bondi,Michel,androtatingblack holes. MNRAS 504, 5039–5053. doi:10.1093/mnras/ stab1127,arXiv:2102.12529. Artymowicz, P., Clarke, C.J., Lubow, S.H., Pringle, J.E., 1991. The Effect of an External Disk on the Orbital Elements of a Central Binary. ApJ 370, L35. doi:10.1086/185971. Artymowicz, P., Lubow, S.H., 1994. Dynamics of Binary-Disk...

    work page doi:10.1093/mnras/ 1991

  2. [2]

    Edgar, R., 2004

    doi:10.1007/s00159-015-0091-5. Edgar, R., 2004. A review of Bondi-Hoyle-Lyttleton accretion. New A Rev. 48, 843–859. doi:10.1016/j.newar.2004. 06.001,arXiv:astro-ph/0406166. Eggleton, P., 2011. Evolutionary Processes in Binary and Mul- tiple Stars. Eggleton,P.P.,1983. AproximationstotheradiiofRochelobes. ApJ 268, 368–369. doi:10.1086/160960. Elsender, D.,...

    work page doi:10.1007/s00159-015-0091-5 2004

  3. [3]

    , keywords =

    doi:10.1086/171162. Ivanova, N., Kundu, S., Pourmand, A., 2024. Unified Rapid Mass Transfer. ApJ 971, 64. doi:10.3847/1538-4357/ ad583e,arXiv:2406.04195. Jackson, B., Arras, P., Penev, K., Peacock, S., Marchant, P., 2017.ANewModelofRocheLobeOverflowforShort-period Gaseous Planets and Binary Stars. ApJ 835, 145. doi:10. 3847/1538-4357/835/2/145,arXiv:1612....

    work page doi:10.1086/171162 2024

  4. [4]

    ApJ 951, L12

    End-to-end Kilonova Models of Neutron Star Merg- ers with Delayed Black Hole Formation. ApJ 951, L12. doi:10.3847/2041-8213/acdad2,arXiv:2302.10928. Justesen, A.B., Albrecht, S., 2021. Temperature and Distance Dependence of Tidal Circularization in Close Binaries: A Catalog of Eclipsing Binaries in the Southern Hemisphere Observed by the TESS Satellite. A...

    work page doi:10.3847/2041-8213/acdad2 2041

  5. [5]

    doi:10.1146/annurev-astro-052622-022933 , keywords =

    doi:10.1146/annurev-astro-052622-022933, arXiv:2211.00028. Lajoie, C.P., Sills, A., 2011. Mass Transfer in Binary Stars Using Smoothed Particle Hydrodynamics. II. Eccentric Bi- naries. ApJ 726, 67. doi:10.1088/0004-637X/726/2/67, arXiv:1011.2204. Lei, Z.X., Chen, X.F., Zhang, F.H., Han, Z., 2013. Effects of tidally enhanced stellar wind on the horizontal ...

    work page doi:10.1146/annurev-astro-052622-022933 2011

  6. [6]

    A&A 696, A82

    A comprehensive Gaia view of ellipsoidal and rota- tional red giant binaries. A&A 696, A82. doi:10.1051/ 0004-6361/202453394,arXiv:2502.11667. Nie, J.D., Wood, P.R., Nicholls, C.P., 2017. The Orbital Nature of81EllipsoidalRedGiantBinariesintheLargeMagellanic Cloud. ApJ 835, 209. doi:10.3847/1538-4357/835/2/ 209,arXiv:1702.02376. North, P., Zahn, J.P., 200...

    work page doi:10.3847/1538-4357/835/2/ 2017

  7. [7]

    Ste ¸pień, K., 2000

    doi:10.1093/mnras/stv2548,arXiv:1510.08429. Ste ¸pień, K., 2000. Loss of angular momentum of magnetic Ap stars in the pre-main sequence phase. A&A 353, 227–238. Tassoul, J.L., Tassoul, M., 1992a. A Comparative Study of Synchronization and Circularization in Close Binaries. ApJ 395, 259. doi:10.1086/171647. Tassoul, M., Tassoul, J.L., 1992b. On the Efficie...

    work page doi:10.1093/mnras/stv2548 2000

  8. [8]

    Post-AGB

    doi:10.1086/171680. Tassoul, M., Tassoul, J.L., 1997. On Synchronization in De- tached Close Binaries: Reply to Rieutord and Zahn. ApJ 481, 363–368. doi:10.1086/304037. Tauris, T.M., van den Heuvel, E.P.J., 2023. Physics of Binary StarEvolution.FromStarstoX-rayBinariesandGravitational Wave Sources. doi:10.48550/arXiv.2305.09388. Tejeda, E., Toalá, J.A., 2...

    work page doi:10.1086/171680 1997