Pub Date : 2026-03-18DOI: 10.3847/1538-4357/ae47c0
James M. De Buizer, Wanggi Lim, James T. Radomski and Nicole Karnath
In this eighth paper of the Stratospheric Observatory For Infrared Astronomy-FORCAST series on Milky Way GH ii regions, we present an analysis of the massive star-forming complex W43 Main. We compared our 11–37 μm maps with multiwavelength observations from the near-infrared to radio, and investigated the physical nature of compact sources and dust substructures. We applied spectral energy distribution fitting to constrain properties of the compact infrared objects, and examined the evolutionary states of the extended subregions. We identified 20 compact infrared objects, 16 (80%) of which we classify as massive young stellar object candidates (MYSOs) or candidate MYSOs. W43 Main resides at the junction of the Scutum spiral arm and the Galactic Bar, a location where enhanced turbulence is anticipated and has been proposed as a potential influence on star formation activity. Nevertheless, our analysis shows that its Lyman continuum photon production rate, the mass of its most massive MYSO, and its MYSO density are all consistent with the survey-wide median values. We therefore conclude that, despite W43 Main’s unique Galactic environment, its present star formation activity appears broadly consistent with that of an average Galactic GH ii region.
{"title":"Surveying the Giant H ii Regions of the Milky Way with SOFIA. VIII. W43 Main","authors":"James M. De Buizer, Wanggi Lim, James T. Radomski and Nicole Karnath","doi":"10.3847/1538-4357/ae47c0","DOIUrl":"https://doi.org/10.3847/1538-4357/ae47c0","url":null,"abstract":"In this eighth paper of the Stratospheric Observatory For Infrared Astronomy-FORCAST series on Milky Way GH ii regions, we present an analysis of the massive star-forming complex W43 Main. We compared our 11–37 μm maps with multiwavelength observations from the near-infrared to radio, and investigated the physical nature of compact sources and dust substructures. We applied spectral energy distribution fitting to constrain properties of the compact infrared objects, and examined the evolutionary states of the extended subregions. We identified 20 compact infrared objects, 16 (80%) of which we classify as massive young stellar object candidates (MYSOs) or candidate MYSOs. W43 Main resides at the junction of the Scutum spiral arm and the Galactic Bar, a location where enhanced turbulence is anticipated and has been proposed as a potential influence on star formation activity. Nevertheless, our analysis shows that its Lyman continuum photon production rate, the mass of its most massive MYSO, and its MYSO density are all consistent with the survey-wide median values. We therefore conclude that, despite W43 Main’s unique Galactic environment, its present star formation activity appears broadly consistent with that of an average Galactic GH ii region.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"17 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147471170","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-18DOI: 10.3847/1538-4357/ae4a16
Bin Jiang, Zhuoran Gao, Yan Yang, Francesco Pecora, Kai Gao, Cheng Li, Sean Oughton, William H. Matthaeus and Minping Wan
In solar wind turbulence, the energy transfer/dissipation rate is typically estimated using MHD third-order structure functions calculated using spacecraft observations. However, the inherent anisotropy of solar wind turbulence leads to significant variations in structure functions along different observational directions, thereby affecting the accuracy of energy dissipation rate estimation. An unresolved issue is how to optimise the selection of observation angles under limited directional sampling to improve estimation precision. We conduct a series of MHD turbulence simulations with different mean magnetic field strengths, B0. Our analysis of the third-order structure functions reveals that the global energy dissipation rate estimated around a polar angle of θ = 60∘agrees reasonably with the exact one for 0 ≤ B0/brms ≤ 5, where brms denotes the rms magnetic field fluctuation. The speciality of 60∘ polar angle can be understood by the mean value theorem of integrals, since the spherical integral of the polar-angle component ( ) of the divergence of Yaglom flux is zero, and changes sign around 60∘. Existing theory on the energy flux vector as a function of the polar angle is assessed, and supports the speciality of the 60∘ polar angle. The angular dependence of the third-order structure functions is further assessed with virtual spacecraft data analysis. The present results can be applied to measure the turbulent dissipation rates of energy in the solar wind, which are of potential importance to other areas in which turbulence takes place, such as laboratory plasmas and astrophysics.
{"title":"Angular Dependence of Third-order Law in Anisotropic MHD Turbulence","authors":"Bin Jiang, Zhuoran Gao, Yan Yang, Francesco Pecora, Kai Gao, Cheng Li, Sean Oughton, William H. Matthaeus and Minping Wan","doi":"10.3847/1538-4357/ae4a16","DOIUrl":"https://doi.org/10.3847/1538-4357/ae4a16","url":null,"abstract":"In solar wind turbulence, the energy transfer/dissipation rate is typically estimated using MHD third-order structure functions calculated using spacecraft observations. However, the inherent anisotropy of solar wind turbulence leads to significant variations in structure functions along different observational directions, thereby affecting the accuracy of energy dissipation rate estimation. An unresolved issue is how to optimise the selection of observation angles under limited directional sampling to improve estimation precision. We conduct a series of MHD turbulence simulations with different mean magnetic field strengths, B0. Our analysis of the third-order structure functions reveals that the global energy dissipation rate estimated around a polar angle of θ = 60∘agrees reasonably with the exact one for 0 ≤ B0/brms ≤ 5, where brms denotes the rms magnetic field fluctuation. The speciality of 60∘ polar angle can be understood by the mean value theorem of integrals, since the spherical integral of the polar-angle component ( ) of the divergence of Yaglom flux is zero, and changes sign around 60∘. Existing theory on the energy flux vector as a function of the polar angle is assessed, and supports the speciality of the 60∘ polar angle. The angular dependence of the third-order structure functions is further assessed with virtual spacecraft data analysis. The present results can be applied to measure the turbulent dissipation rates of energy in the solar wind, which are of potential importance to other areas in which turbulence takes place, such as laboratory plasmas and astrophysics.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"110 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147471268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-18DOI: 10.3847/1538-4357/ae47dc
Samrat Biswas, Biman J. Medhi, Motohide Tamura, H.S Das and Jungmi Kwon
We present near-infrared (NIR) and optical linear polarimetry toward the partially embedded cluster AFGL 6366S. The polarization ranges from 0.44% to 10.3% in NIR and from 0.16% to 11.22% in the optical bands. The position angle spans 1°−179° in both the NIR and optical bands. About 22 stars exhibit intrinsic polarization signatures. A polarization hole is evident toward the densest (∼3.4 × 1023 cm−2) and warmest (∼28.8 K) central cluster region. It is attributable to depolarization induced by radiative torque disruption of large grains and a modest contribution from magnetic field tangling. The local magnetic field toward the cluster’s central region is significantly misaligned with both the large-scale Galactic field and the long axis of the filament present in the region. The field morphology wraps around two dense molecular clumps with radii 0.34 and 0.22 pc and N(H2) = (7.9 ± 1.1) × 1022 cm−2 and (4.3 ± 0.5) × 1022 cm−2, respectively. The clumps are embedded in the filamentary structure and represent locally accelerated stages of mass accumulation. Gravitationally driven mass flows, largely perpendicular to the local magnetic field, produce a U-shaped field curvature across the filament axis. The plane-of-sky magnetic field strengths toward the two clumps are 447.91 ± 83.81 μG and 396.66 ± 73.64 μG. The corresponding mass-to-flux ratios (λ ∼ 1.34 and 0.82) indicate that one clump is magnetically supercritical and the other is subcritical. The Alfvén Mach numbers ∼ 0.395 and 0.393 indicate that both clumps are in the sub-Alfvénic state.
{"title":"Probing the Magnetic Fields and Dust Properties in the Young Embedded Star-forming Region AFGL 6366S Using Near-infrared and Optical Linear Polarimetry*","authors":"Samrat Biswas, Biman J. Medhi, Motohide Tamura, H.S Das and Jungmi Kwon","doi":"10.3847/1538-4357/ae47dc","DOIUrl":"https://doi.org/10.3847/1538-4357/ae47dc","url":null,"abstract":"We present near-infrared (NIR) and optical linear polarimetry toward the partially embedded cluster AFGL 6366S. The polarization ranges from 0.44% to 10.3% in NIR and from 0.16% to 11.22% in the optical bands. The position angle spans 1°−179° in both the NIR and optical bands. About 22 stars exhibit intrinsic polarization signatures. A polarization hole is evident toward the densest (∼3.4 × 1023 cm−2) and warmest (∼28.8 K) central cluster region. It is attributable to depolarization induced by radiative torque disruption of large grains and a modest contribution from magnetic field tangling. The local magnetic field toward the cluster’s central region is significantly misaligned with both the large-scale Galactic field and the long axis of the filament present in the region. The field morphology wraps around two dense molecular clumps with radii 0.34 and 0.22 pc and N(H2) = (7.9 ± 1.1) × 1022 cm−2 and (4.3 ± 0.5) × 1022 cm−2, respectively. The clumps are embedded in the filamentary structure and represent locally accelerated stages of mass accumulation. Gravitationally driven mass flows, largely perpendicular to the local magnetic field, produce a U-shaped field curvature across the filament axis. The plane-of-sky magnetic field strengths toward the two clumps are 447.91 ± 83.81 μG and 396.66 ± 73.64 μG. The corresponding mass-to-flux ratios (λ ∼ 1.34 and 0.82) indicate that one clump is magnetically supercritical and the other is subcritical. The Alfvén Mach numbers ∼ 0.395 and 0.393 indicate that both clumps are in the sub-Alfvénic state.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147471171","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-18DOI: 10.3847/1538-4357/ae47fb
Konstantin Gerbig, Min-Kai Lin and 明楷 林
We revisit the diffusive instability in dusty disks that arises when the dust mass diffusivity and/or viscosity decrease sufficiently steeply with increasing dust density. Our updated model includes an incompressible viscous gas that responds azimuthally and couples to the dust through drag. We show that the basic criterion for diffusion-slope-driven instability remains approximately βdiff ≲ −2 for small dust-stopping times, with gas feedback providing only modest quantitative changes for parameters motivated by streaming instability turbulence. We perform nonlinear numerical calculations and confirm linear growth and mode selection toward the fastest-growing wavenumber. However, for power-law closures with βdiff < 0, the nonlinear evolution does not saturate. Instead, steepening gradients amplify the nonlinear dust pressure term and drive finite-time collapse into increasingly sharp spikes. Motivated by the absence of multidimensional saturation channels from our 1D framework, we test a simple piecewise closure, in which the negative diffusion slope operates only over a finite-density interval. This modification eliminates blowup and produces peak densities controlled by the imposed saturation scale. Our results support diffusive instabilities as a linear organizing mechanism in dusty turbulence, while highlighting that realistic nonlinear saturation requires additional physics beyond the present closure.
{"title":"Diffusive Instabilities in Dusty Disks: Linear Growth and Nonlinear Breakdown","authors":"Konstantin Gerbig, Min-Kai Lin and 明楷 林","doi":"10.3847/1538-4357/ae47fb","DOIUrl":"https://doi.org/10.3847/1538-4357/ae47fb","url":null,"abstract":"We revisit the diffusive instability in dusty disks that arises when the dust mass diffusivity and/or viscosity decrease sufficiently steeply with increasing dust density. Our updated model includes an incompressible viscous gas that responds azimuthally and couples to the dust through drag. We show that the basic criterion for diffusion-slope-driven instability remains approximately βdiff ≲ −2 for small dust-stopping times, with gas feedback providing only modest quantitative changes for parameters motivated by streaming instability turbulence. We perform nonlinear numerical calculations and confirm linear growth and mode selection toward the fastest-growing wavenumber. However, for power-law closures with βdiff < 0, the nonlinear evolution does not saturate. Instead, steepening gradients amplify the nonlinear dust pressure term and drive finite-time collapse into increasingly sharp spikes. Motivated by the absence of multidimensional saturation channels from our 1D framework, we test a simple piecewise closure, in which the negative diffusion slope operates only over a finite-density interval. This modification eliminates blowup and produces peak densities controlled by the imposed saturation scale. Our results support diffusive instabilities as a linear organizing mechanism in dusty turbulence, while highlighting that realistic nonlinear saturation requires additional physics beyond the present closure.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147471265","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-18DOI: 10.3847/1538-4357/ae4a98
Li Wang, 莉 王, Chenyu He, 辰昱 贺, Chengyuan Li, 程远 李, Gang Li and 刚 李
Tidal interactions in close binaries play a key role in the long-term rotational and orbital evolution. The distributions of circularization across open clusters (OCs) place strong observational constraints on tidal dissipation in binaries. However, direct observational constraints on synchronization among binaries in OCs remain limited. For the 125 Myr OC Pleiades, this work combines cluster membership from Gaia Data Release 3, rotation periods from the K2 mission, and orbital solutions of the binary population from a long-term spectroscopic survey to investigate the degree of tidal synchronization in each binary by comparing the pseudosynchronization period to the rotation period of the primary stars. Among 42 binaries with reliable orbital periods Porb and rotation periods, we identify seven tidally synchronized systems with Porb ≲ 8.6 days, including one early-type system and six late-type systems. For binaries with longer Porb, primaries generally are supersynchronized, and most systems are eccentric. We find a synchronization transition near Porb ≈ 8.6–14 days, comparable to the known circularization period (Porb ≈ 7.2 days) in the Pleiades, which suggests similar critical period scales for synchronization and circularization in this coeval population. Synchronization depends much more strongly on mass ratio than on primary mass. Most synchronized systems in Pleiades have high mass ratios and are likely to evolve into double white dwarf systems. Tides likely impose strong rotational braking on close early-type binaries, while their influence on late-type close binaries is weaker, and their spins largely follow the single-star sequence.
{"title":"Tidal Synchronization of Binaries in Pleiades","authors":"Li Wang, 莉 王, Chenyu He, 辰昱 贺, Chengyuan Li, 程远 李, Gang Li and 刚 李","doi":"10.3847/1538-4357/ae4a98","DOIUrl":"https://doi.org/10.3847/1538-4357/ae4a98","url":null,"abstract":"Tidal interactions in close binaries play a key role in the long-term rotational and orbital evolution. The distributions of circularization across open clusters (OCs) place strong observational constraints on tidal dissipation in binaries. However, direct observational constraints on synchronization among binaries in OCs remain limited. For the 125 Myr OC Pleiades, this work combines cluster membership from Gaia Data Release 3, rotation periods from the K2 mission, and orbital solutions of the binary population from a long-term spectroscopic survey to investigate the degree of tidal synchronization in each binary by comparing the pseudosynchronization period to the rotation period of the primary stars. Among 42 binaries with reliable orbital periods Porb and rotation periods, we identify seven tidally synchronized systems with Porb ≲ 8.6 days, including one early-type system and six late-type systems. For binaries with longer Porb, primaries generally are supersynchronized, and most systems are eccentric. We find a synchronization transition near Porb ≈ 8.6–14 days, comparable to the known circularization period (Porb ≈ 7.2 days) in the Pleiades, which suggests similar critical period scales for synchronization and circularization in this coeval population. Synchronization depends much more strongly on mass ratio than on primary mass. Most synchronized systems in Pleiades have high mass ratios and are likely to evolve into double white dwarf systems. Tides likely impose strong rotational braking on close early-type binaries, while their influence on late-type close binaries is weaker, and their spins largely follow the single-star sequence.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"43 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147471269","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-18DOI: 10.3847/1538-4357/ae4a1d
Lei Huang, Yang Guo, Zhen Li, Jinhan Guo and Mingde Ding
Solar jets, collimated plasma ejections driven by magnetic reconnection, play a vital role in energy transport and coronal heating. While rotational motions in jets are often attributed to magnetic field untwisting, alternative explanatory mechanisms remain possible. This study investigates a rotating jet in an active region observed on 2023 August 1 using multiwavelength observations from the Atmospheric Imaging Assembly, Chinese Hα Solar Explorer, and Interface Region Imaging Spectrograph, combined with a self-consistent time-dependent magnetofrictional model and magnetohydrodynamic simulation. Spectral diagnostics reveal coexisting red and blueshifts along the edges and central axis of the jet, indicating helical plasma motion within a twisted magnetic structure. Numerical simulations demonstrate that the jet’s rotation arises from plasma propagating along helical open field lines, formed via reconnection between a pre-existing flux rope and overlying magnetic fields. Contrary to classical untwisting models, both linear and rotational velocities decrease with altitude during the jet propagation. These results highlight that the observed rotation results from plasma spiral motion along twisted fields rather than untwisting dynamics of the magnetic field itself, providing new insights into solar jet energetics and their connection to broader solar phenomena.
{"title":"Rotation of a Solar Jet Driven by Plasma Flow along Helical Magnetic Fields in an Active Region","authors":"Lei Huang, Yang Guo, Zhen Li, Jinhan Guo and Mingde Ding","doi":"10.3847/1538-4357/ae4a1d","DOIUrl":"https://doi.org/10.3847/1538-4357/ae4a1d","url":null,"abstract":"Solar jets, collimated plasma ejections driven by magnetic reconnection, play a vital role in energy transport and coronal heating. While rotational motions in jets are often attributed to magnetic field untwisting, alternative explanatory mechanisms remain possible. This study investigates a rotating jet in an active region observed on 2023 August 1 using multiwavelength observations from the Atmospheric Imaging Assembly, Chinese Hα Solar Explorer, and Interface Region Imaging Spectrograph, combined with a self-consistent time-dependent magnetofrictional model and magnetohydrodynamic simulation. Spectral diagnostics reveal coexisting red and blueshifts along the edges and central axis of the jet, indicating helical plasma motion within a twisted magnetic structure. Numerical simulations demonstrate that the jet’s rotation arises from plasma propagating along helical open field lines, formed via reconnection between a pre-existing flux rope and overlying magnetic fields. Contrary to classical untwisting models, both linear and rotational velocities decrease with altitude during the jet propagation. These results highlight that the observed rotation results from plasma spiral motion along twisted fields rather than untwisting dynamics of the magnetic field itself, providing new insights into solar jet energetics and their connection to broader solar phenomena.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"18 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147471270","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We investigate the bar fraction in galaxy pairs from the Sloan Digital Sky Survey to assess how galaxy interactions affect bar structures. Compared to isolated galaxies, close pairs exhibit a significantly reduced bar fraction at projected separations within 25 kpc. This reduction is driven almost entirely by systems showing clear merger or disturbance signatures, indicating that tidal interactions suppress bars. The decline is dominated by a decrease in weak bars, while the fraction of strong bars remains largely unchanged. Bar suppression is primarily associated with major mergers and is strongest in massive host galaxies. A weaker but statistically significant suppression is detected in minor mergers only for massive galaxies with small bulges. In contrast, no significant dependence of bar suppression on the relative orientation between pair members is found. These findings provide observational evidence that tidal perturbations in major mergers play a key role in regulating bar evolution.
{"title":"Reduction of the Bar Fraction in Paired Galaxies in the SDSS","authors":"Linlin Li, 林林 李, Shuai Feng, 帅 冯, Shiyin Shen, 世银 沈, Qi’an Deng, 淇安 邓, Ying Zu, 颖 祖, Wenyuan Cui and 文元 崔","doi":"10.3847/1538-4357/ae4bdc","DOIUrl":"https://doi.org/10.3847/1538-4357/ae4bdc","url":null,"abstract":"We investigate the bar fraction in galaxy pairs from the Sloan Digital Sky Survey to assess how galaxy interactions affect bar structures. Compared to isolated galaxies, close pairs exhibit a significantly reduced bar fraction at projected separations within 25 kpc. This reduction is driven almost entirely by systems showing clear merger or disturbance signatures, indicating that tidal interactions suppress bars. The decline is dominated by a decrease in weak bars, while the fraction of strong bars remains largely unchanged. Bar suppression is primarily associated with major mergers and is strongest in massive host galaxies. A weaker but statistically significant suppression is detected in minor mergers only for massive galaxies with small bulges. In contrast, no significant dependence of bar suppression on the relative orientation between pair members is found. These findings provide observational evidence that tidal perturbations in major mergers play a key role in regulating bar evolution.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"64 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147471271","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We investigate whether the long photometric cycles observed in double-periodic variables (DPVs) can arise from nodal precession of a tilted accretion disk driven by the tidal torque of the companion. Within a simple analytical framework, we derive testable relations linking the long-to-orbital period ratio to the binary mass ratio, the normalized disk size, and the disk tilt angle β, which itself can be inferred from the long-cycle amplitude, orbital inclination i, and disk luminosity fraction. The model naturally reproduces the two observed long-cycle light-curve morphologies—sinusoidal and double hump—distinguished by the geometric criterion i + β ≤ 90° versus i + β > 90°. Applying these relations to a sample of DPVs, we find that the inferred disk sizes are physically reasonable and consistent with independent light-curve modeling for a nonnegligible subset of systems. Our results show that tidal nodal precession represents a viable and potentially important contributor to the long-period variability of DPVs and provide a quantitative framework for future observational and theoretical studies.
{"title":"Long Photometric Cycles in Double-periodic Variables from Nodal Precession of a Tilted Accretion Disk","authors":"Cheng-Liang Jiao, 承亮 焦, Er-gang Zhao, Liying Zhu and Azizbek Matekov","doi":"10.3847/1538-4357/ae4b30","DOIUrl":"https://doi.org/10.3847/1538-4357/ae4b30","url":null,"abstract":"We investigate whether the long photometric cycles observed in double-periodic variables (DPVs) can arise from nodal precession of a tilted accretion disk driven by the tidal torque of the companion. Within a simple analytical framework, we derive testable relations linking the long-to-orbital period ratio to the binary mass ratio, the normalized disk size, and the disk tilt angle β, which itself can be inferred from the long-cycle amplitude, orbital inclination i, and disk luminosity fraction. The model naturally reproduces the two observed long-cycle light-curve morphologies—sinusoidal and double hump—distinguished by the geometric criterion i + β ≤ 90° versus i + β > 90°. Applying these relations to a sample of DPVs, we find that the inferred disk sizes are physically reasonable and consistent with independent light-curve modeling for a nonnegligible subset of systems. Our results show that tidal nodal precession represents a viable and potentially important contributor to the long-period variability of DPVs and provide a quantitative framework for future observational and theoretical studies.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"128 11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147471273","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-18DOI: 10.3847/1538-4357/ae40ab
Kate D. Alexander, Raffaella Margutti, Sebastian Gomez, Michael Stroh, Ryan Chornock, Tanmoy Laskar, Y. Cendes, Edo Berger, Tarraneh Eftekhari, Noah Franz, Aprajita Hajela, B. D. Metzger, Giacomo Terreran, Michael Bietenholz, Collin Christy, Fabio De Colle, S. Komossa, Matt Nicholl, Enrico Ramirez-Ruiz, Richard Saxton, Genevieve Schroeder, Peter K. G. Williams and William Wu
Recent observations presented in Y. Cendes et al. show that optically selected tidal disruption events (TDEs) commonly produce delayed radio emission that can peak years after disruption. Here, we explore the multiwavelength properties of a sample of radio-observed optically selected TDEs, to shed light on the physical process(es) responsible for the late-rising radio emission. We combine new late-time X-ray observations with archival optical, UV, X-ray, and radio data to conclude that a diversity of accretion-driven outflows may power the delayed radio emission in TDEs. Our analysis suggests that some late radio outflows may be launched by a delayed phase of super-Eddington accretion onto the central supermassive black hole (SMBH), while others may result from a state transition to a “low–hard” radiatively inefficient accretion flow or the deceleration of an off-axis relativistic jet. We find that TDEs with delayed radio emission are less likely to exhibit helium emission lines at early times (p = 0.002) and may have larger optical/UV photospheric radii (p = 0.026) than other TDEs, possibly also indicating that the onset of SMBH accretion is delayed in these systems. Our results have implications for our understanding of state changes in SMBH accretion flows, the circularization timescale for TDE debris, and the prevalence of off-axis jets in TDEs, and they motivate systematic long-term monitoring of these unique transients. The objects in our sample with the brightest radio emission are also detected in the Very Large Array Sky Survey, demonstrating that all-sky radio surveys can play an important role in discovering unexpected properties of the TDE population.
Y. Cendes等人最近发表的观测结果表明，光学选择的潮汐破坏事件（TDEs）通常会产生延迟的无线电发射，在破坏数年后达到峰值。在这里，我们探索了射电观测到的光学选择tde样品的多波长特性，以阐明导致晚升射电发射的物理过程。我们将新的晚期x射线观测与档案光学、紫外、x射线和射电数据结合起来，得出结论：吸积驱动的流出物的多样性可能是tde延迟射电发射的动力。我们的分析表明，一些晚期射电流出可能是由超级爱丁顿吸积的延迟阶段发射到中央超大质量黑洞（SMBH）上，而其他可能是由状态转变到“低硬”辐射低效吸积流或离轴相对论性射流的减速造成的。我们发现具有延迟射电发射的tde在早期不太可能出现氦发射线（p = 0.002），并且可能比其他tde具有更大的光学/紫外光球半径（p = 0.026），这也可能表明SMBH吸积的开始在这些系统中被延迟。我们的研究结果对我们理解SMBH吸积流的状态变化、TDE碎片的循环时间尺度以及TDE中离轴射流的流行具有重要意义，并且它们激发了对这些独特瞬态的系统长期监测。在我们的样本中，射电发射最亮的天体也在甚大阵巡天中被探测到，这表明全天射电巡天可以在发现TDE种群的意外特性方面发挥重要作用。
{"title":"The Multiwavelength Context of Delayed Radio Emission in Tidal Disruption Events: Evidence for Accretion-driven Outflows","authors":"Kate D. Alexander, Raffaella Margutti, Sebastian Gomez, Michael Stroh, Ryan Chornock, Tanmoy Laskar, Y. Cendes, Edo Berger, Tarraneh Eftekhari, Noah Franz, Aprajita Hajela, B. D. Metzger, Giacomo Terreran, Michael Bietenholz, Collin Christy, Fabio De Colle, S. Komossa, Matt Nicholl, Enrico Ramirez-Ruiz, Richard Saxton, Genevieve Schroeder, Peter K. G. Williams and William Wu","doi":"10.3847/1538-4357/ae40ab","DOIUrl":"https://doi.org/10.3847/1538-4357/ae40ab","url":null,"abstract":"Recent observations presented in Y. Cendes et al. show that optically selected tidal disruption events (TDEs) commonly produce delayed radio emission that can peak years after disruption. Here, we explore the multiwavelength properties of a sample of radio-observed optically selected TDEs, to shed light on the physical process(es) responsible for the late-rising radio emission. We combine new late-time X-ray observations with archival optical, UV, X-ray, and radio data to conclude that a diversity of accretion-driven outflows may power the delayed radio emission in TDEs. Our analysis suggests that some late radio outflows may be launched by a delayed phase of super-Eddington accretion onto the central supermassive black hole (SMBH), while others may result from a state transition to a “low–hard” radiatively inefficient accretion flow or the deceleration of an off-axis relativistic jet. We find that TDEs with delayed radio emission are less likely to exhibit helium emission lines at early times (p = 0.002) and may have larger optical/UV photospheric radii (p = 0.026) than other TDEs, possibly also indicating that the onset of SMBH accretion is delayed in these systems. Our results have implications for our understanding of state changes in SMBH accretion flows, the circularization timescale for TDE debris, and the prevalence of off-axis jets in TDEs, and they motivate systematic long-term monitoring of these unique transients. The objects in our sample with the brightest radio emission are also detected in the Very Large Array Sky Survey, demonstrating that all-sky radio surveys can play an important role in discovering unexpected properties of the TDE population.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147470893","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-17DOI: 10.3847/1538-4357/ae47dd
Koshvendra Singh, Joe P. Ninan, Zhen Guo, Valentin D. Ivanov, David A. H. Buckley, Devendra K. Ojha, Andrew Monson, Tarak Chand, Saurabh Sharma, Ram Kesh Yadav, Devendra K. Sahu, Pramod Kumar, Vardan Elbakyan, Sergei Nayakshin, Vitor Fermiano, Min Fang, Jura Borissova, Wen Ping Chen, Franz-Josef Hambsch, Radostin Kurtev, Calum Morris, Javier Osses, Vania Rodríguez, Tanvi Sharma, Bandari Srikanth, Thanawuth Thanathibodee, Wei-Hao Wang and Yuting Zhou
Accretion-driven outbursts in young stellar objects remain poorly understood, largely limited by a statistically small sample of closely followed-up events. This underscores the importance of a thorough exploration of each outbursting object. We studied a peculiar outbursting system, Gaia24ccy, which exhibited two Δg ∼ 3.8 mag outbursts in 2019 and 2024. The system consists of two unresolved, nearly identical, and rapidly rotating young stars: Gaia24ccy A (1.1419 days) and Gaia24ccy B (1.7898 days). Periodogram analyses just before the onset of the outbursts suggest Gaia24ccy B to be the outbursting component. Unlike any previously known EXor sources, the two outburst profiles show very similar evolution: both rose at the same rate for the first 15 days, followed by multiple “subbursts” on timescales of 10−20 days. The 2019 outburst lasted 145–255 days, while the 2024 outburst persisted for 367 days. We infer the unstable region to lie at rtrigger ≃ 0.019–0.047 au (∼5–12.3R⋆). The accreted mass per event, Macc ∼ 10−5 M⊙, can be provided by a compact inner-disk reservoir. The photometric rise and decay timescales, together with the mid-infrared (MIR) color evolution, favor a thermal–viscous trigger in a hot inner disk, while the presence of rich emission-line spectra indicates concurrent magnetospheric compression—together forming a hybrid picture. Finally, we explain the reddening of the MIR color observed during the outburst as a consequence of the competing emission from the viscous disk and the photosphere.
{"title":"Gaia24ccy: An Outburst Followed the Footsteps of its Predecessor","authors":"Koshvendra Singh, Joe P. Ninan, Zhen Guo, Valentin D. Ivanov, David A. H. Buckley, Devendra K. Ojha, Andrew Monson, Tarak Chand, Saurabh Sharma, Ram Kesh Yadav, Devendra K. Sahu, Pramod Kumar, Vardan Elbakyan, Sergei Nayakshin, Vitor Fermiano, Min Fang, Jura Borissova, Wen Ping Chen, Franz-Josef Hambsch, Radostin Kurtev, Calum Morris, Javier Osses, Vania Rodríguez, Tanvi Sharma, Bandari Srikanth, Thanawuth Thanathibodee, Wei-Hao Wang and Yuting Zhou","doi":"10.3847/1538-4357/ae47dd","DOIUrl":"https://doi.org/10.3847/1538-4357/ae47dd","url":null,"abstract":"Accretion-driven outbursts in young stellar objects remain poorly understood, largely limited by a statistically small sample of closely followed-up events. This underscores the importance of a thorough exploration of each outbursting object. We studied a peculiar outbursting system, Gaia24ccy, which exhibited two Δg ∼ 3.8 mag outbursts in 2019 and 2024. The system consists of two unresolved, nearly identical, and rapidly rotating young stars: Gaia24ccy A (1.1419 days) and Gaia24ccy B (1.7898 days). Periodogram analyses just before the onset of the outbursts suggest Gaia24ccy B to be the outbursting component. Unlike any previously known EXor sources, the two outburst profiles show very similar evolution: both rose at the same rate for the first 15 days, followed by multiple “subbursts” on timescales of 10−20 days. The 2019 outburst lasted 145–255 days, while the 2024 outburst persisted for 367 days. We infer the unstable region to lie at rtrigger ≃ 0.019–0.047 au (∼5–12.3R⋆). The accreted mass per event, Macc ∼ 10−5 M⊙, can be provided by a compact inner-disk reservoir. The photometric rise and decay timescales, together with the mid-infrared (MIR) color evolution, favor a thermal–viscous trigger in a hot inner disk, while the presence of rich emission-line spectra indicates concurrent magnetospheric compression—together forming a hybrid picture. Finally, we explain the reddening of the MIR color observed during the outburst as a consequence of the competing emission from the viscous disk and the photosphere.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"44 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147465704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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