Orbital pacing of environmental changes during the Late Devonian-Early Carboniferous (Famennian-Viséan, ~ 372-330 Ma) greenhouse Earth is investigated using high-resolution gamma-ray (GR) logs, chemostratigraphy (ICP-OES, ICP-MS, pXRF), and cyclostratigraphic analysis (multitaper method, wavelet transforms, Fischer plots, Dynamic Noise after Orbital Tuning sea-level modeling) of two petroleum wells from the Jurgurra Terrace, Canning Basin, Western Australia. The sedimentary successions (Nullara, May River, Laurel, Anderson formations) reveal a ubiquitous ~ 5-Myr orbital eccentricity amplitude modulation cycle, along with shorter Milankovitch cycles (405-kyr long-eccentricity, 100-kyr short-eccentricity, 40-50-kyr obliquity, 20-25-kyr precession), and sedimentation rates of 3.5-4.5 cm/kyr derived from evolutionary Time Optimization (eTimeOpt) and orbital tuning. Key findings are: (1) The Hangenberg Event (HE; ~ 3925-4030 m in Rafael 1) and Lower Alum Shale Event (LASE; ~ 3690-3770 m) coincide with 405-kyr eccentricity maxima, imposing monsoonal intensification, nutrient input, and euxinia (recorded by high V/Cr, U/Th, and organic carbon burial). (2) The Late Tournaisian Cooling Event (LTCE; ~ 3500 m) is synchronous with 100-kyr eccentricity-driven glacial-interglacial cycles, with lowered sea level, high Rb/Sr values, and siliciclastic progradation. (3) Wavelet analysis reveals a hierarchical orbital structure in which precession-paced ventilation ended anoxic intervals (e.g., post-HE re-oxygenation), whereas Fischer plots show highstand systems tracts equate to condensed, organic-rich sediment at eccentricity maxima. Geochemical proxies (Sr/Ba, Mg/Ca) also record salinity fluctuations that can be linked to orbital-scale hydrological cycling. DYNOT modeling illustrates that ~ 5-Myr amplitude modulation cycles controlled long-term climate stability, enhancing redox and sea-level extremes. These cycles, supported by global analogs (Ordovician-Silurian, Late Cenozoic), emphasize orbital forcing as the leading cause of greenhouse climate instability and its implications for determining Earth's climatic sensitivity in the absence of ice. The research connects celestial mechanics and Devonian-Carboniferous environmental disasters with improved predictive models for orbital signatures in the sedimentary record.

Abstract In this work, we present an updated prescription of contemporary tidal dissipation theory adapted for rapid binary population synthesis. Our simplified expressions encode the dependence of tidal dissipation on stellar structure, stratification, and tidal forcing frequency, while remaining computationally efficient. We implement these prescriptions in the rapid population synthesis code COMPAS, and demonstrate the self-consistent coupling of tides with stellar evolution and binary properties such as orbital periods, spins, and eccentricities for several representative binary systems. When compared with commonly used tidal prescriptions, our equilibrium tidal dissipation efficiencies can be stronger by 1–2 orders of magnitude for low-mass main sequence and giant-type stars, and dynamical tides can vary by 1–7 orders of magnitude due to the explicit dependence on internal stellar structure and the presence of inertial wave dissipation. Despite our simplistic approach, our models agree with detailed stellar simulations to within an order of magnitude across tidal dissipation mechanisms.

The supermassive black hole (Sgr A*) in the Galactic center is surrounded by the S-star cluster consisting of young stars on eccentric orbits. Recently, the an S-star binary system, called D9, was found. Its detection was based on periodic emission in Brackettγ (Brγ). Since Brγ is considered a signature of accretion, this emission could originate from the interaction of a binary and its circumbinary disk. However, due to the gravitational interaction between Sgr A* and the binary, the disk could be short-lived. We investigated the evolution of the disk around a stellar binary while orbiting Sgr A*. We used the framework for coupling a gravity solver (for the binary and Sgr. A*) with a hydrodynamics solver (for the disk). AMUSE We find that, irrespective of the initial disk inner and outer radii, it eventually settles between 5.2a_ in and 0.28 Hill radii of the binary. Here, a_ in is the semimajor axis of the binary D9. The inclination of the circumbinary disk follows that of the binary, which evolves due to the von Zeipel-Lidov-Kozai (vZLK) mechanism induced by Sgr A*. The mean eccentricity of the disk is approximately in antiphase with the eccentricity evolution of the binary. We find a vZLK timescale of T_ vZLK which is two orders of magnitude shorter than the value reported earlier. As a consequence, D9 has undergone multiple vZLK oscillations in its lifetime of 2.7 Myr. We find that the disk shows periodic bursts of mass loss on the vZLK timescale, suggesting that the mass loss itself is in part driven by the vZLK mechanism. The secular evolution observed in both the binary and the disk are consistent with theoretical predictions. We find the disk loses ∼7% ± 2% of its mass every vZLK cycle. If we extrapolate this mass loss, the disk will have 1% of its current mass left after another ∼4 Myr. D9 will then be ∼6.7 Myr old, which is on the same order as the current average age of S cluster members. The vZLK-driven mass loss could therefore explain the absence of Brγ emission from other S cluster members.

Abstract The inflated transiting super-Neptune WASP-107b is believed to be generating measurable internal heat, possibly by tidal dissipation of energy in a slightly eccentric orbit. Small orbital eccentricities can be difficult to measure using radial velocity data alone. Fortunately, the orbital phase of the secondary eclipse is very sensitive to eccentricity. Wu et al. recently claimed a possible secondary eclipse using JWST NIRSpec archival data. We here demonstrate that photometry from four Spitzer eclipses confirms Wu et al.’s eclipse phase, and we measure e cos ( ω ) = 0.0143 ± 0.0014 . This establishes a lower limit to the orbital eccentricity, and we also measure the eclipse depth and day side brightness temperature in the sum of Spitzer’s 3.6 and 4.5 μ m bands. We obtain T b = 820 ± 26 K, consistent within the errors with the temperature at the evening limb inferred from JWST transit spectroscopy.

Abstract Most of the geodetic satellites observed with Satellite Laser Ranging (SLR) are placed in near-circular orbits. This paper uses simulations to discuss the advantages of launching a satellite into an eccentric orbit from the perspective of the quality of geodetic parameters. For the first time, we evaluate how eccentricity, inclination, and semi-major axis affect the accuracy of determining SLR-based parameters, including station coordinates, Earth rotation parameters, geocenter coordinates, and low-degree Earth's gravity field coefficients. We found that eccentric orbits substantially improve gravity field recovery, especially for low-degree zonal, tesseral, and sectorial coefficients. The greatest impact is observed for the odd-zonal terms: the formal errors for C 30 and C 50 decrease by over 90% compared to the current 10-satellite constellation. The even-degree zonal coefficients (C 20 , C 40 , C 60 ) also improve, achieving gains of 70–80% at optimal inclinations. Even-degree coefficients prefer eccentric orbits, and their importance increases substantially with a large semi-major axis, leading to a more noticeable improvement in the quality of the estimated coefficients. To minimize formal errors of the gravity-field coefficients, inclinations of 20–40° or 140–160° are favored for even-degree zonal and tesseral coefficients. In contrast, sectorial and odd-degree zonal coefficients prefer inclinations of 75–105°, particularly for satellites with a semi-major axis of 7800 km. Additionally, eccentric orbits improve visibility from the southern hemisphere for specific perigee placements and increase the separability of the coefficients of the gravity potential in terms of the correlations.

Abstract The dynamical history of a planetary system is recorded in the present day architecture of its constituent planets’ sizes, orbital periods, and eccentricities. Studying the relationships between these quantities for large populations provides a window into the processes by which planetary systems form and evolve. Recently, G. J. Gilbert et al. performed a hierarchical Bayesian analysis of 1646 planets from the Kepler census, demonstrating a strong relationship between planet radius R p and orbital eccentricity e . Here, we build upon that work to search for correlations between eccentricity and system architecture, focusing on compact systems of small planets. We find that small planets on short orbits ( P < 4 days) show evidence of tidal circularization. This trend is well established for Jovian planets but a novel finding for super-Earths and sub-Neptunes. We reproduce the known wherein trend single-transiting systems possess elevated eccentricities relative to their multitransiting counterparts. We further show that systems with two transiting planets have higher eccentricities than those with three or more transiting planets. When compared to population synthesis models, these multiplicity–eccentricity relationships imply that Kepler singles have intrinsic multiplicity ∼3 and Kepler multis have intrinsic multiplicity ∼4−6. We detect no statistically significant associations between eccentricity and planetary period ratios, gap complexity, size inequality, or size ordering. We interpret these findings as evidence either in favor of a quiescent formation history or against dynamical processes that excite eccentricity but not inclination. Subsignificant relationships between eccentricity and architecture imply that subtle, multifactor trends may be detectable in the future using more sophisticated statistical techniques.

Abstract Stellar obliquity serves as a key diagnostic for tracing the dynamical evolution of bound systems—from giant planets and brown dwarfs to stellar binaries—revealing whether these diverse populations share analogous histories. Here, we report the first obliquity measurement for a double M dwarf system, determined via the Rossiter–McLaughlin effect. The spin axis of the primary star, TOI-5375 ( M * = 0.62 ± 0.02 M ⊙ ), is well aligned with the orbit of its low-mass stellar companion ( M c = 84.8 ± 1.5 M J , P = 1.72 days) with a projected obliquity of λ = − 13 . ° 5 − 13.8 + 12.4 and a true 3D obliquity of ψ = 37 . ° 5 − 13.4 + 10.6 . The result indicates that the system either formed with a primordially aligned configuration or has undergone tidal realignment. We further investigate obliquity patterns across giant planets, brown dwarfs, and binary stars. It turns out that a few obliquity trends observed in giant planets also tentatively exhibit in the latter two higher-mass populations: (1) well-aligned orbits are preferentially found around cooler host stars ( T eff ≤ 6250 K); (2) wide-orbit ( a / R * ≥ 10) companions are predominantly aligned; and (3) no significant correlation shows up between obliquity and orbital eccentricity in any of the companion classes. By modeling ∣ λ ∣ with a two-component Gaussian distribution, we find that the low-∣ λ ∣ components of binary stars and brown dwarfs are more concentrated near zero than those of giant planets, while the high-∣ λ ∣ components of brown dwarfs and binaries remain unclear due to the small sample size.

Abstract The origin of Saturn’s rings has been debated for decades. Measurements from Voyager and Cassini have suggested that the rings could be as young as ∼100 Myr and composed of nearly pure ice. Several scenarios have been proposed to explain these properties. One hypothesis is that the rings formed through the recent tidal disruption of a preexisting moon, Chrysalis, which experienced a close encounter with Saturn following its highly eccentric orbit. However, the mechanism by which this hypothesis would have formed the rings remains largely unexplored, in particular, whether Chrysalis could supply ring material of the desired mass and composition. To address these questions, we perform smoothed particle hydrodynamics simulations to investigate the tidal response of Chrysalis during close encounters with Saturn. Our results demonstrate that preferential tidal stripping of the ice mantle from a differentiated Chrysalis can produce rings with both mass and composition resembling the present rings—provided that the closest encounter occurs between the parabolic Roche limits for ice ∼1.53 R S (Saturn radii) and rock ∼1.07 R S —consistent with J. Wisdom et al. Moreover, multiple close encounters can extend the effective disruption limit by spinning up the body, enhancing the tidal stripping efficiency. Following close encounters, the rocky remnant of Chrysalis would have been removed in less than a few kyr, either by collision with Saturn or ejection onto a hyperbolic orbit. These findings support the hypothesis that Saturn’s rings could originate from a recent lost moon, and imply a highly dynamical evolution of the Saturnian system over the past few hundred Myr.

Abstract The oceanic tidal magnetic field, mainly driven by the circular orbital motion of the Moon, is an essential part of the time‐varying geomagnetic field. The previously adopted time‐harmonic (TH) base worked well in fitting the primary tidal field, but extracting the other weaker modes like the was difficult with only a single satellite. The tidal field, although it can be derived fortuitously by the gradient data set relying on the side‐by‐side measurements of Swarm, remains a significant challenge in single satellite measurement. Here, we introduce the ephemerides predictor (EP) base, which corrects the Moon's eccentric orbit, to study the tidal fields based on the pre‐processed data set of China Seismo‐Electromagnetic Satellite (CSES) and Swarm‐Alpha. Our results suggest that the EP base is able to derive the tidal fields of both and when the gradient data set is unavailable.

Studying planetary interactions in exoplanet systems informs theories of planet formation and evolution, providing essential context for understanding our own solar system. We combine spectroscopy, transit photometry, transit timing variations, and astrometry to characterize the TOI-201 system. The cotransiting system consists of a super-Earth, warm Jupiter, and massive companion at 5.8-, 53-, and 2900-day orbital periods, respectively. We perform dynamical simulations to study the past and future of the system. von-Zeipel-Kozai-Lidov oscillations emerge as the most plausible scenario to explain the outer companion's high orbital eccentricity, with planet-planet scattering a possible but less likely contender. Because of nonzero mutual inclinations between the planets, the system is visibly evolving on very short timescales, with the current cotransiting configuration ending in 200 years.

Abstract Various processes can induce long-lived overdense rings and arcs in protoplanetary and AGN accretion discs, such as the accumulation of gas at the outer edge of the dead zone, or the infall of material. Using the local approximation of dynamical friction, we investigate the orbital evolution of a low-mass highly-eccentric point-mass accretor (perturber) embedded in an isothermal disc hosting a density ring. We specifically consider the regime in which the eccentricity exceeds four times the disc aspect ratio. For prograde perturbers, orbits that cross the ring progressively circularize while their semi-major axes converge toward the ring radius. As a result, perturbers accumulate, forming a population ring superimposed on the gaseous ring. The ring therefore acts as a migration trap for these eccentric orbits. We also find that prograde orbits tangent to the ring, either at apocentre or pericentre, remain tangential throughout their evolution; perturbers confined to these trajectories experience the highest accretion rates. In contrast, retrograde perturbers always migrate inward. Once the semi-major axis becomes smaller than the ring radius, the eccentricity grows, but not enough for the orbit to intersect the ring again. We also discuss how feedback effects, such as jet launching and thermal torques, could modify the effective forces acting on the perturbers.

ABSTRACT We identify shell-like tidal structures in flattened haloes that appear stream-like when viewed under different projections. This dependence on projection demonstrates how changes in the host halo can directly impact the formation and classification of tidal debris, highlighting the challenges of relying solely on visual inspections. To address this, we employ our clustering-based classification framework to systematically categorize the tidally disrupted satellites into stream-like and shell-like structures. Our host consists of a static three-component Milky Way model with flattening introduced along the z-axis Navarro–Frenk–White dark halo. We consider three halo shape scenarios: a spherical halo $q=1$, an extremely oblate halo with $q=0.5$, and a prolate halo where $q=1.5$. We evolve three types subhaloes: a highly radial massive subhalo favouring shell formation, an eccentric orbit leading to stream formation, and an intermediate orbit case. We first classify the tidal structures visually using face-on and edge-on density projections of the 3D position distribution. This visual inspection reveals shell-like and stream-like formations across all the face-on projections of different halo shapes, while the edge-on projection leads to contrary classifications in some cases. To resolve these ambiguities, we apply the classification method developed in our earlier work analysing the structures in ordered density, radial and energy–angle space. We further investigate the spatial dispersion of stream-like structures and the rate at which core density reduces as the flattening parameter varies. Our results demonstrate that the variations in halo shape can affect the formation and classification of tidal debris, as well as the spatial dispersion and core density evolution of streams. This offers insights on how both the initial condition of the subhalo and the structural properties of the host halo play a crucial role in determining the morphology of tidal features. These findings offer new insights into the role of dark matter halo geometry in shaping the tidal structure formation and its contribution to hierarchical galaxy formation and evolution.

We confirmed four spectroscopic binary candidates using new observations obtained with SALT. Three SB2 systems (HD 20784, HD 43519A, HD 62153A) exhibit circular orbits with periods shorter than 10 days, whereas one hierarchical triple system (HD 56024) contains a close binary with an inner eccentric orbit with a period of approximately 14 days, composed of nearly identical stellar components, and a rapidly rotating star on an outer eccentric orbit with a period of approximately 400 days. For two additional SB2 candidates (HD 198174 and HD 208433), our new observations do not allow us to derive reliable orbital solutions.

Context . Theoretical formation models and exoplanet detection surveys indicate that systems with multiple giant planets are common. Aims . We investigate how multiple super-thermal-mass planets embedded in a circumstellar disk shape the dust distribution and examine the consequences for interpreting disk substructures and inferring planetary properties. Methods . We performed two-dimensional hydrodynamical simulations with a modified PLUTO code, treating dust as Lagrangian particles in a wide range of sizes. We analyzed systems with two planets of different masses and orbital separations, comparing them to the single-planet scenario. We generated synthetic ALMA continuum maps using RADMC-3D and computed the relative impact velocities of dust particles to assess potential limitations to grain growth. Results . Dust morphologies in multi-planet systems cannot be described as a simple superposition of single-planet gaps. Secular planetary perturbations can generate multiple dust traps and asymmetric structures, while also exciting significant eccentricities in dust particle orbits. As a consequence, the locations and widths of dust rings and gaps depend on the size of the particles, the masses of the planet, and the orbital configurations. Synthetic continuum images may hide gaps carved by multiple planets, thereby complicating the interpretation of observed substructures. In addition, eccentricities induced in dust orbits lead to stronger gas drag, reducing the Stokes number for a given particle size, and the enhanced relative velocities associated with eccentric orbits can further suppress grain growth, promoting fragmentation and replenishment of small dust grains.

Feasibility assessment of formation flight control by differential drag in eccentric orbit for the FACTORS mission

ABSTRACT We present the first comprehensive study of the eclipsing binary TIC 263930790, in which space-based photometry, spectroscopy, and eclipse-timing variations (ETVs) jointly reveal its hierarchical multiple-star architecture. We determine the effective temperature of the primary via spectral energy distribution modelling, and perform a simultaneous light and radial velocity (RV) curve analysis to derive the absolute parameters of the inner binary. Comparison with stellar evolutionary models places both components on the main sequence and indicates a system age of approximately 1.3 Gyr, with the primary component approaching the terminal-age main sequence while the system remains well detached. Broadening function (BF) analysis reveals spectral signatures of an additional luminous component, allowing for the measurement of its RVs. The ETVs are well reproduced by a model consisting of two light-time effect (LiTE) signals plus a quadratic ephemeris term, indicating the presence of two stellar-mass companions on eccentric outer orbits and favouring a hierarchical 2 + 1 + 1 quadruple architecture. By comparing the ETV-derived solutions with the observed RV signal of the additional body, we find that the outermost companion provides an excellent match, whereas attributing the RV modulation to the inner companion is strongly disfavoured. N-body integrations further demonstrate that the inferred configuration is dynamically stable over 200 Myr, with bounded secular variations of the orbital elements. TIC 263930790 thus represents a rare example of a dynamically stable, young hierarchical quadruple system whose architecture and evolutionary state can be robustly constrained in the absence of outer eclipses.

Abstract We use MESA to model the future evolution of the 21 Gaia neutron star (NS)–main-sequence binaries (orbital period P orb ∼ 200–1000 days, eccentricity e ≳ 0.2) under two prescriptions: eccentric mass-transfer and enforced efficient circularization before the initiation of mass-transfer. All systems terminate as NS–white dwarfs (WDs), albeit different mass-transfer modes yield sharply divergent properties. Under eccentric mass-transfer, binaries are driven to higher eccentricities (final e ≳ 0.6 mostly) and P orb ∼ 1000–4000 days. Mass-transfer episodes in eccentric orbits are brief (≲10 6 yr), transfer only a few ×10 −2 M ⊙ , and produce only mildly recycled pulsars (spin-period P spin ∼ 100 ms) with low-mass helium WDs. Artificially circularized mass-transfer produces shorter final orbital periods of P orb ∼ 200–2000 days and allows mass-transfer to occur for ∼10 7 yr, so that the NSs accrete ∼0.1 M ⊙ , yielding fully recycled millisecond pulsars (MSPs) with P spin ∼ few–30 ms, including nine systems with carbon–oxygen WDs. Enabling super-Eddington accretion up to 100× the canonical limit makes even eccentric channels efficiently produce MSPs. Incorporating an adaptive, field-dependent magnetic-field-decay timescale, our models reproduce the observed Gyr-long radio lifetimes of MSPs. Independent of the mass-transfer treatment, the descendants of these Gaia systems do not resemble the bulk of the known Galactic MSP–WD binaries, which are nearly circular with P orb ≲ 100 days. The observed MSP–WDs are likely produced by systems with more massive companions that undergo unstable mass-transfer and NS in a common-envelope phase—an evolutionary channel that is not relevant for the Gaia binaries.

Abstract In this work, we analytically investigate the effects of the scalar self-force exerted by a massless scalar field on a particle in a slightly eccentric orbit around a Schwarzschild black hole. By solving the Klein–Gordon equation in the curved spacetime background, using a combination of post-Newtonian (PN) expansion, and small-eccentricity approximation, we derive explicit expressions for the self-force components at the particle location, as well as for the associated energy and angular momentum fluxes. Our results are valid up to sixth PN order and fourth order in eccentricity ( e 4 ). We compare asymptotic fluxes with those obtained in Trestini (2024 Phys. Rev. D 109 104003) for scalar–tensor (ST) theories. Once the relation between the two approaches has been established, we find perfect agreement by fixing the asymptotic value of the scalar field in ST theory φ 0 = 1.

Abstract Scattering of stars by interstellar clouds or massive clumps increases the stellar velocity dispersion and promotes a radial disk profile that is exponential. Here we show that such scattering reaches a steady-state distribution function of stellar eccentricity, after which eccentricity increases and decreases occur at equal rates. The implication is that clump/cloud scattering recircularizes eccentric stellar orbits, keeping the stellar velocity dispersion in a limited range. This recircularization regulates disk heating and maintains kinematic coherence, contributing to the longevity of disk structures. The eccentricity distribution function and the presence of recircularizing cloud–star interactions are independent of cloud mass, but the timescale to reach equilibrium decreases with increasing mass. The calculations are made in the simplest possible disk system to highlight the effects of scattering without contamination from spiral waves, star formation, and other processes. The calculations also reveal a bifurcation in the disk evolutions whereby in a minority of cases, temporary asymmetries in the clump spatial distribution drive the disks to an end state of increased velocity dispersion and orbital eccentricity corresponding to early-type disks. Overall, the models emphasize an important physical process that can make and maintain an exponential stellar disk in all galaxies with a cloudy interstellar medium.

Abstract We present a study of equal-mass hyperbolic encounters, embedded in a uniform gaseous medium. Using linear perturbation theory, we calculate the density wakes excited by these perturbers and compute the resulting forces exerted on them by the gas. We compute the changes to orbital energy, orbital angular momentum, and apsidal precession across a wide range of eccentricities and pericenter Mach numbers. We identify six distinct classes of hyperbolic orbits, differing through their wake structure and subsequent orbital evolution. We find the gas to always dissipate orbital energy, leading to smaller semimajor axes and higher pericenter Mach numbers. The orbital angular momentum can either increase or decrease, whereas we typically find the orbital eccentricity to be damped, promoting supersonic gas captures. Additionally, we find that the force exerted by the gas is not strictly frictional, particularly for asymptotically subsonic trajectories. Therefore, despite the orbit-integrated changes to orbital parameters being similar to those predicted by the E. C. Ostriker prescription, the time evolution of the density wakes and the instantaneous forces exerted on the perturbers are significantly different.