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solar energetic particles (seps) are one of the extreme space weather phenomena. a huge sep event increases the radiation dose received by aircrews, who should be warned of such events as early as possible. we developed a warning system for aviation exposure to seps. this article describes one component of the system, ... | interplanetary particle transport simulation for warning system for aviation exposure to solar energetic particles |
we study the helicity density patterns which can result from the emerging bipolar regions. using the relevant dynamo model and the magnetic helicity conservation law we find that the helicity density patterns around the bipolar regions depend on the configuration of the ambient large-scale magnetic field, and in genera... | the magnetic helicity density patterns from non-axisymmetric solar dynamo |
we present in this letter the first global comparison between traditional line-tied steady-state magnetohydrodynamic models and a new, fully time-dependent thermodynamic magnetohydrodynamic simulation of the global corona. to approximate surface magnetic field distributions and magnitudes around solar minimum, we use t... | time-dependent dynamics of the corona |
most hot jupiters have extended envelopes of gas that spread beyond their roche lobes. a typical envelope is weakly gravitationally bound to the planet and, therefore, its structure and properties are strongly affected by stellar wind disturbances, for example, coronal mass ejections. earlier, we performed gas-dynamic ... | mhd model of the interaction of a coronal mass ejection with the hot jupiter hd 209458b |
the expansion of hot electrons in flaring magnetic loops is crucial to understanding the dynamics of solar flares. in this paper we investigate, for the first time, the transport of hot electrons in a magnetic mirror field based on a 1d particle-in-cell simulation model. the hot electrons with small pitch angles transp... | expansion of solar coronal hot electrons in an inhomogeneous magnetic field: 1d pic simulation |
aims: we investigate synthetic observational signatures generated from numerical models of transverse waves propagating in complex (braided) magnetic fields.methods: we consider two simulations with different levels of magnetic field braiding and impose periodic, transverse velocity perturbations at the lower boundary.... | forward modelling of mhd waves in braided magnetic fields |
we present 2.5d global, ideal magnetohydrodynamic (mhd) simulations of magnetically and rotationally driven protostellar jets from keplerian accretion discs, wherein only the initial magnetic field strength at the inner radius of the disc, bi, is varied. using the amr-mhd code azeus, we self-consistently follow the jet... | mhd simulations of the formation and propagation of protostellar jets to observational length-scales |
magnetism defines the complex and dynamic solar corona. coronal mass ejections (cmes) are thought to be caused by stresses, twists, and tangles in coronal magnetic fields that build up energy and ultimately erupt, hurling plasma into interplanetary space. even the ever-present solar wind possesses a three-dimensional m... | untangling the global coronal magnetic field with multiwavelength observations |
the collapse of the magnetic rotating protostellar cloud with mass of $10\,m_{\odot}$ is numerically studied. the initial ratios of the thermal, magnetic, and rotational energies of the cloud to the modulus of its gravitational energy are 0.3, 0.2 and 0.01, respectively. the emphasis is on the evolution and properties ... | primary disks and their observational appearance in collapsing magnetic rotating protostellar clouds |
it has been shown in a previous work that torsional alfvén waves can drive turbulence in nonuniform coronal loops with a purely axial magnetic field. here we explore the role of the magnetic twist. we modeled a coronal loop as a transversely nonuniform straight flux tube, anchored in the photosphere, and embedded in a ... | transition to turbulence in nonuniform coronal loops driven by torsional alfvén waves. ii. extended analysis and effect of magnetic twist |
the evolution of collapsing clouds embedded in different star-forming environments is investigated using three-dimensional non-ideal magnetohydrodynamics simulations considering different cloud metallicities (z/z_⊙ = 0, 10-5, 10-4, 10-3, 10-2, 10-1, and 1) and ionization strengths (cζ = 0, 0.01, 1, and 10, where cζ is ... | driving conditions of protostellar outflows in different star-forming environments |
aims: magnetic fields play an important role during the formation and evolution of stars. of particular interest in stellar evolution is what effect they have on the transport angular momentum and mixing of chemical elements along the radial direction in radiative regions. current theories suggest a dynamo loop as the ... | stability of toroidal magnetic fields in stellar interiors |
coronal jets are eruptions identified by a collimated, sometimes twisted spire. they are small-scale energetic events compared with flares. using multiwavelength observations from the solar dynamics observatory/atmospheric imaging assembly and a magnetogram from hinode/spectro-polarimeter (hinode/sp), we study the form... | simulation of a solar jet formed from an untwisting flux rope interacting with a null point |
in this paper, for a number of significantly different parameters of a localized plane layer of collisionless electron-proton plasma and an external magnetic field parallel to its surface, we perform a detailed numerical analysis of the evolution of the magnetic field structure and the dynamics of plasma expansion into... | weibel instability and deformation of an external magnetic field in the region of decay of a strong discontinuity in a plasma with hot electrons |
context. several observations of stellar jets show evidence of x-ray emitting shocks close to the launching site. in some cases, including young stellar objects (ysos) at different stages of evolution, the shocked features appear to be stationary. we study two cases, both located in the taurus star-forming region. hh 1... | structure of x-ray emitting jets close to the launching site: from embedded to disk-bearing sources |
we present a new method to investigate the effective magnetic field decay of isolated neutron stars, from the analysis of the long-term timing data of a large sample of radio pulsars. there are some differences between the distributions of frequency’s second derivatives of the pulsar spins with different effective fiel... | the effective magnetic field decay of radio pulsars: insights from the statistical properties of their spin frequency's second derivatives |
we introduce a theory for the development of a transitional column density σtp between the lognormal and the power-law forms of the probability distribution function in a molecular cloud. our turbulent magnetohydrodynamic simulations show that the value of σtp increases as the strength of both the initial magnetic fiel... | the transition from a lognormal to a power-law column density distribution in molecular clouds: an imprint of the initial magnetic field and turbulence |
we present a systematic study of periodic x-ray sources in the limiting window (lw), a ∼70 arcmin2 field representative of the inner galactic bulge and the target of ∼1 ms chandra observations. using the gregory-loredo algorithm, which applies bayes's theorem to the phase-folded light curve and is well suited for irreg... | periodic x-ray sources in the galactic bulge: application of the gregory-loredo algorithm |
the view on velocity structures in molecular clouds and their relationship with magnetic fields (b field) has evolved during the past decade from almost no correlation to highly parallel. our numerical simulations suggest a more nuanced picture: depending on whether the self-gravity is dynamically dominant, the velocit... | velocity anisotropy in self-gravitating molecular clouds. ii. observation |
by means of the monte carlo method, we simulate the evolutionary distribution of accreting neutron stars (nss) in the magnetic field versus spin period (b-p) diagram where the accretion induced magnetic-field decay model is exploited. the simulated results show that by mass accretion the b-p distribution of the accreti... | the simulation of the magnetic field and spin period evolution of accreting neutron stars |
we present hydrodynamical simulations of the interaction of coronal mass ejections (cme) in the interplanetary medium (ipm). in these events, two consecutive cmes are launched from the sun in similar directions within an interval of time of a few hours. in our numerical model, we assume that the ambient solar wind is c... | numerical simulations of icme-icme interactions |
coronal supra-arcade downflows (sads) are observed as dark trails descending toward hot turbulent-fan-shaped regions. due to the large temperature values and gradients in these fan regions, the thermal conduction (tc) should be very efficient. while several models have been proposed to explain the triggering and the ev... | mhd simulations of coronal supra-arcade downflows including anisotropic thermal conduction |
starting from an exact, steady-state, force-free solution of the magnetohydrodynamic (mhd) equations, we investigate how resistive current layers are induced by perturbing line-tied three-dimensional magnetic equilibria. this is achieved by the superposition of a weak perturbation field in the domain, in contrast to st... | simulations of 3d magnetic merging: resistive scalings for null point and qsl reconnection |
context. it is generally assumed that magnetic fields play an important role in the formation and evolution of protoplanetary disks. one way of observationally constraining magnetic fields is to measure polarized emission and absorption produced by magnetically aligned elongated dust grains. the fact that radiation als... | characterization of mid-infrared polarization due to scattering in protoplanetary disks |
context. rotation period measurements of low-mass stars show that the spin distributions in young clusters do not exhibit the spin-up expected due to contraction in the phase when a large fraction of stars is still surrounded by accretion discs. many physical models have been developed to explain this feature based on ... | effects of accretion on the structure and rotation of forming stars |
magnetars are a group of very young neutron stars with extremely strong magnetic fields. they provide a unique laboratory for discovering and testing physics in extreme conditions. magnetars exhibit relatively slow rotation compared with other young pulsars, and they undergo fast spin down. both properties suggest the ... | observational prospects for magnetars with gecam |
the mhd version of the adaptive mesh refinement (amr) code, mg, has been employed to study the interaction of thermal instability, magnetic fields, and gravity through 3d simulations of the formation of collapsing cold clumps on the scale of a few parsecs, inside a larger molecular cloud. the diffuse atomic initial con... | striations, integrals, hourglasses, and collapse - thermal instability driven magnetic simulations of molecular clouds |
models of highly inhomogeneous baryosynthesis of the baryonic asymmetric universe allow for the existence of macroscopic domains of antimatter, which could evolve in a globular cluster of antimatter stars in our galaxy. we assume the symmetry of the evolution of a globular cluster of stars and antistars based on the sy... | researching of magnetic cutoff for local sources of charged particles in the halo of the galaxy |
rapidly spinning magnetic grains can acquire large magnetic dipole moments due to the barnett effect. here we study the new effect of barnett magnetic dipole-dipole interaction on grain-grain collisions and grain growth, assuming that grains are spun up by radiative torques. for the ideal situation in which grains have... | effects of barnett magnetic dipole-dipole interaction on grain growth and destruction |
we derive a corrected analytical solution for the propagation and enhanced phase mixing of torsional alfvén waves, in a potential magnetic field with exponentially divergent field lines, embedded in a stratified solar corona. further we develop a code named tawas that calculates the analytic solution describing torsion... | enhanced phase mixing of torsional alfvén waves in stratified and divergent solar coronal structures - paper i. linear solutions |
using 2d particle-in-cell plasma simulations, we study electron acceleration by temperature anisotropy instabilities, assuming conditions typical of above-the-loop-top sources in solar flares. we focus on the long-term effect of te,⊥ > te,∥ instabilities by driving the anisotropy growth during the entire simulation ... | stochastic electron acceleration by temperature anisotropy instabilities under solar flare plasma conditions |
context. relative magnetic helicity is conserved by magneto-hydrodynamic evolution even in the presence of moderate resistivity. for that reason, it is often invoked as the most relevant constraint on the dynamical evolution of plasmas in complex systems, such as solar and stellar dynamos, photospheric flux emergence, ... | additivity of relative magnetic helicity in finite volumes |
magnetic field generation and evolution models that are capable of describing a large body of observational material are currently available for different celestial bodies. despite recent decades of great success in numerical magnetic hydrodynamics and in detailed research into some specific problems, asymptotic method... | current results on the asymptotics of dynamo models |
we simulate the evolution of the stellar wind and the supernova remnant (snr) originating from a runaway massive star in a uniform galactic environment based on three-dimensional magnetohydrodynamics models. taking the stellar wind into consideration, we can explain the radio morphologies of many snrs. the directions o... | how does the stellar wind influence the radio morphology of a supernova remnant? |
this paper presents the spatio-temporal evolution of magnetic field due to the nonlinear coupling between fast magnetosonic wave (fmsw) and low frequency slow alfvén wave (saw). the dynamical equations of finite frequency fmsw and saw in the presence of ponderomotive force of fmsw (pump wave) has been presented. numeri... | nonlinear effects associated with fast magnetosonic waves and turbulent magnetic amplification in laboratory and astrophysical plasmas |
resolution studies of test problems set baselines and help define minimum resolution requirements, however, resolution studies must also be performed on scientific simulations to determine the effect of resolution on the specific scientific results. we perform a resolution study on the formation of a protostar by model... | resolving numerical star formation: a cautionary tale |
the separation of a filament and sigmoid is observed during an x1.4 flare on 2012 july 12 in solar active region 11520, but the corresponding change in magnetic field is not clear. we construct a data-constrained magnetohydrodynamic simulation of the filament-sigmoid system with the flux rope insertion method and magne... | data-constrained mhd simulation for the eruption of a filament-sigmoid system in solar active region 11520 |
recent direct numerical simulations (dns) of large-scale turbulent dynamos in strongly stratified layers have resulted in surprisingly sharp bipolar structures at the surface. here, we present new dns of helically and non-helically forced turbulence with and without rotation and compare with corresponding mean-field si... | sharp magnetic structures from dynamos with density stratification |
in addition to the gamma-ray binaries which contain a compact object, high energy (he) and very high energy (vhe) gamma-rays have also been detected from colliding-wind binaries. the collision of the winds produces two strong shock fronts, one for each wind, both surrounding a shock region of compressed and heated plas... | colliding-wind binaries as a source of tev cosmic rays |
the high resolution imager (hrieuv) telescope of the extreme ultraviolet imager (eui) instrument onboard solar orbiter has observed euv brightenings, so-called campfires, as fine-scale structures at coronal temperatures. the goal of this paper is to compare the basic geometrical (size, orientation) and physical (intens... | a statistical comparison of euv brightenings observed by so/eui with simulated brightenings in nonpotential simulations |
magnetic field extrapolation is a fundamental tool to reconstruct the three-dimensional magnetic field above the solar photosphere. however, the prevalently used force-free field model might not be applicable in the lower atmosphere with non-negligible plasma β, where the crucial process of flux rope formation and evol... | magnetic field extrapolation in active region well comparable to observations in multiple layers |
we explain some phenomena existing generally in the timing residuals: amplitude and sign of the second derivative of a pulsar's spin-frequency (ddot{ν }), some sophisticated residual patterns, which also change with the time span of data segments. the sample is taken from hobbs et al., in which the pulsar's spin-freque... | understanding the residual patterns of timing solutions of radio pulsars with a model of magnetic field oscillation |
the temporal evolution of a spectrum during a steeply rising submillimeter (thz) burst that occurred on 2003 november 2 was investigated in detail for the first time. observations show that the flux density of the thz spectrum increased steeply with frequency above 200 ghz. their average rising rates reached a value of... | study of temporal evolution of emission spectrum in a steeply rising submillimeter burst |
we discuss different exotic phases and components of matter from the crust to the core of neutron stars based on theoretical models for equations of state relevant to core collapse supernova simulations and neutron star merger. parameters of the models are constrained from laboratory experiments. it is observed that eq... | neutron stars: laboratories for fundamental physics under extreme astrophysical conditions |
we have studied the large scale dynamo process forced with helical magnetic energy. the magnetically driven dynamo is not so well studied as kinetically forced dynamo. it has been thought to represent the amplification of magnetic field in the stellar corona, accretion disk, or plasma lab. however, the interaction betw... | negative turbulent magnetic diffusivity $\\beta$ effect in a magnetically forced system |
the evolution of toroidal field instability is essential to understand the topology of the magnetic fields observed in early-type stars, or in the isothermal core of the red giants. we study the non-linear evolution of the instability of a predominant toroidal field stored in a stably stratified stellar interior in sph... | non-linear simulations of the tayler instability |
previously derived faraday rotation constraints on the volume-filling intergalactic magnetic field (igmf) have used analytical models that made a range of simplifying assumptions about magnetic field evolution in the intergalactic medium and did not consider the effect of baryonic feedback on large-scale structures. in... | revision of faraday rotation measure constraints on the primordial magnetic field using the illustristng simulation |
it is generally believed that angular momentum is distributed during the gravitational collapse of the primordial star forming cloud. however, so far there has been little understanding of the exact details of the distribution. we use the modified version of the gadget-2 code, a three-dimensional smoothed-particle hydr... | angular momentum distribution during the collapse of primordial star-forming clouds |
we model the evolution of the spin frequency's second derivative v̈ and the braking index n of radio pulsars with simulations within the phenomenological model of their surface magnetic field evolution, which contains a long-term power-law decay modulated by short-term oscillations. for the pulsar psr b0329+54, a model... | modeling the evolution and distribution of the frequency's second derivative and the braking index of pulsar spin |
we use the 2.5-d electromagnetic particle-in-cell simulation code to investigate the acceleration of electrons in solar coronal holes through the interaction of alfvén waves with an interplume region. the interplume is modeled by cavity density gradients that are perpendicular to the background magnetic field. the aim ... | electron acceleration and small-scale coherent structure formation by an alfvén wave propagating in coronal interplume region |
we have constrained the charge-mass (ɛ -m ) phase space of millicharged particles through the simulation of the rotational evolution of neutron stars, where an extra slow-down effect due to the accretions of millicharged dark matter particles is considered. for a canonical neutron star of m =1.4 m⊙ and r =10 km with ty... | constraints on millicharged particles by neutron stars |
we employ the supernova fallback disk model to simulate the spin evolution of isolated young neutron stars (nss). we consider the submergence of the ns magnetic fields during the supercritical accretion stage and its succeeding reemergence. it is shown that the evolution of the spin periods and the magnetic fields in t... | unifying neutron star sub-populations in the supernova fallback accretion model |
energy conversion via reconnecting current sheets is common in space and astrophysical plasmas. frequently, current sheets disrupt at multiple reconnection sites, leading to the formation of plasmoid structures between sites, which might affect energy conversion. we present in situ evidence of the firehose instability ... | in situ evidence of firehose instability in multiple reconnection |
star formation involves gravity, turbulence, magnetic fields, and feedback from new stars through jets, radiation and winds. the evolution of the density probability distribution function (ρ-pdf) is directly related to the star formation rate (sfr), forming the basis of several star formation models. we utilize two run... | evolution of the gas density in a simulated star-forming cloud with stellar feedback |
using three-dimensional magnetohydrodynamics simulations, the driving of protostellar jets is investigated in different star-forming cores with the parameters of magnetic field strength and mass accretion rate. powerful high-velocity jets appear in strongly magnetized clouds when the mass accretion rate on to the proto... | can high-velocity protostellar jets help to drive low-velocity outflow? |
i will review our current knowledge of magnetism in hot stars, in particular the origin and occurrence of magnetic fields in these stars with a radiative envelope, as well as the impact of the magnetic fields on many aspects such as the internal structure of the star, its circumstellar environment, and stellar evolutio... | magnetism in hot stars |
the solar abundances of fe and of the cno elements play an important role in addressing a number of important issues such as the formation, structure, and evolution of the sun and the solar system, the origin of the chemical elements, and the evolution of stars and galaxies. despite the large number of papers published... | the impact of surface dynamo magnetic fields on the chemical abundance determination |
the rotational evolution of an accreting pre-main-sequence star is influenced by its magnetic interaction with its surrounding circumstellar disk. using the pluto code, we perform 2.5d magnetohydrodynamic, axisymmetric, time-dependent simulations of star-disk interaction—with an initial dipolar magnetic field structure... | magnetic braking of accreting t tauri stars: effects of mass accretion rate, rotation, and dipolar field strength |
compact objects, such as neutron stars and black holes, are characterized by the presence of strong magnetic fields that are crucial to explain the high-energy emission from these sources. such magnetic fields may be subject to complex evolution inside the hosting relativistic plasmas, like dynamo-like processes amplif... | creation and dissipation of magnetic fields in non-ideal grmhd simulations |
stars and their corresponding protoplanetary disks form in diverse environments. to account for these natural variations, we investigate the formation process around nine solar mass stars with a maximum resolution of 2 au in a giant molecular cloud of (40 pc)$^3$ in volume by using the adaptive mesh refinement code \ra... | accounting for the diversity in stellar environments |
we perform mhd simulations of a thin resistive and viscous accretion disk around a neutron star with the surface dipolar magnetic field of 108 gauss. the system evolution is followed during the interval of 500 millisecond pulsar rotations. matter is accreted through a stable accretion column from the disk onto the star... | mhd simulations of resistive viscous accretion disk around millisecond pulsar |
context. previous studies show that the physical structures and kinematics of a region depend significantly on the ionisation fraction. these studies have only considered these effects in non-ideal magnetohydrodynamic simulations with microturbulence. the next logical step is to explore the effects of turbulence on ion... | ionisation in turbulent magnetic molecular clouds. i. effect on density and mass-to-flux ratio structures |
the performed magnetohydrodynamic simulation examines the importance of magnetofluid evolution, which naturally leads to current sheets in the presence of three-dimensional (3d) magnetic nulls. the initial magnetic field is constructed by superposing a 3d force-free field on a constant axial magnetic field. the initial... | simulated evolution of three-dimensional magnetic nulls leading to generation of cylindrically-shaped current sheets |
context. uranus is the only planet in the solar system whose rotation axis and orbital plane are nearly parallel to each other. uranus is also the planet with the largest angle between the rotation axis and the direction of its magnetic dipole (roughly 59°). consequently, the shape and structure of its magnetospheric t... | a physical model for the magnetosphere of uranus at solstice time |
to understand how stars can form in the interstellar medium (ism), it has to be understood how cold (~ 10 k) and dense gas (> 10^{4} cm^{-3}) can emerge during the evolution of the ism. with the herschel telescope it was found that most of this dense star forming gas is organised in filamentary structures.to underst... | the formation of dense gas in low- and high-mass star forming regions |
while the sun is a quiet and well-balanced star now, during its first few million years it possessed a strong magnetic field and actively accreted material from its circumstellar environment. theoretical models predict that under certain circumstances the interaction of a strongly magnetic star and its circumstellar di... | magnetic field and accretion in ex lup |
in this lecture on stellar magnetism we discuss how the dynamo generated magnetic field shapes the extended hot atmosphere and how the feedback loop between rotation, convection, turbulence, dynamo action and braking by stellar wind influences the secular evolution and the rotational history of solarlike stars. we disc... | stellar magnetism: bridging dynamos and winds |
stellar chromospheres and winds represent universal attributes of stars on the cool portion of h-r diagram. in this paper we derive observational constrains for the chromospheric heating and wind acceleration from cool evolved stars and examine the role of alfven waves as a viable source of energy dissipation and momen... | the magnetic coupling of chromospheres and winds from late type evolved stars: role of mhd waves |
recent results of magnetohydrodynamic (mhd) simulations are presented treating the launching of jets from young stellar object accretion disks. the simulations consider the evolution of magnetically diffusive disks that eject high-speed outflows. a few exemplary results are presented: (i) the disk structural evolution ... | modeling the magnetized accretion and outflows in young stellar objects |
we present an analytical model to investigate the production of pebbles and their radial transport through a protoplanetary disk (ppd) with magnetically driven winds. while most of the previous analytical studies in this context assumed that the radial turbulent coefficient is equal to the vertical dust diffusion coeff... | on the dynamics of pebbles in protoplanetary disks with magnetically driven winds |
the dynamical coupling between solar chromospheric plasma and the magnetic field is investigated by numerically solving a fully self-consistent, two-dimensional initial-value problem for the nonlinear collisional mhd equations including electric resistivity, thermal conduction, and, in some cases, gas-dynamic viscosity... | numerical mhd simulation of the coupled evolution of plasma and magnetic field in the solar chromosphere. i. gradual and impulsive energisation |
we study the resistive evolution of a localized self-organizing magnetohydrodynamic equilibrium. in this configuration the magnetic forces are balanced by a pressure force caused by a toroidal depression in the pressure. equilibrium is attained when this low-pressure region prevents further expansion into the higher-pr... | resistive evolution of toroidal field distributions and their relation to magnetic clouds |
we use ensemble machine learning algorithms to study the evolution of magnetic fields in magnetohydrodynamic (mhd) turbulence that is helically forced. we perform direct numerical simulations of helically forced turbulence using mean field formalism, with electromotive force (emf) modeled both as a linear and non-linea... | exploring helical dynamos with machine learning: regularized linear regression outperforms ensemble methods |
the origin and evolution of magnetic fields in the universe is still an open question. observations of galaxies at high-redshift give evidence for strong galactic magnetic fields even in the early universe which are consistently measured at later times up to the present age. however, primordial magnetic fields and seed... | astrophysical dynamos and the growth of magnetic fields in high-redshift galaxies |
the removal of ism of disk galaxies through ram pressure stripping (rps) has been extensively studied in numerous simulations (see roediger 2009 and references therein). the models show that rps has a significant impact on galaxy evolution (truncation of the ism will lead to a decrease in star formation and a change in... | mhd simulations of ram pressure stripping of disk galaxies |
the fermi gamma-ray space telescope greatly increased the number of known pulsars in the gamma-ray band. it was discovered that pulsars often emit a significant fraction of their spin-down energy in gamma-rays, offering a new powerful diagnostic tool of neutron star magnetic field structure. the modeling of gamma-ray d... | physics of pulsar magnetospheres |
the common envelope (ce) phase is critical for the formation of close binary stars with at least one compact star. during this phase, a giant star engulfs its companion, which spirals into the giant's envelope. the envelope is ejected and a close binary system results. the ejection mechanism is unknown and predicting t... | hydrodynamics of the common envelope phase in binary stellar evolution. |
we investigate equilibrium height of a flux rope, and its internal equilibrium in a realistic plasma environment by carrying out numerical simulations of the evolution of systems including a current-carrying flux rope. we find that the equilibrium height of a flux rope is approximately described by a power-law function... | numerical experiments on the evolution in coronal magnetic configurations including a filament in response to the change in the photosphere |
the dynamo action likely present within fully convective regions is explored through global-scale 3-d simulations. these simulations provide a contextual analog for the convective dynamos that are likely operating deep within the interiors of fully convective low mass stars. a logarithmic range of rotation rates is con... | the magnetic furnace: examining fully convective dynamos and the influence of rotation |
bow shock formation, magnetic reconnection and plasmoid ejection are thought to be present in most planetary environments. the aim of this work is to show that the presence of this kind of structures in the vicinity of planets is not restrictive to magnetized bodies. the presence of a interplanetary magnetic field carr... | formation of structures in the wind of sun-like stars by the presence of unmagnetized terrestrial planets |
quantum simulation with ultracold gases provides a highly customizable platform for the study of many-body physics, shedding new light on important physical systems. magnetic fields or, equivalently in the case of a uniform, static field, rotation are especially important parameters for many-body systems including nucl... | geometric squeezing of a degenerate fermi gas |
when solving mysteries about distant astronomical objects, sometimes it pays to take inspiration from sources closer to home. in todays example, strange fluid behavior in the earths oceans combined with a healthy helping of magnetic fields may provide the answer to a long-standing puzzle about the changing composition ... | solving a stellar abundance problem (with a little help from our oceans) |
star formation informs our understanding of astrophysical processes at many different scales ranging from galaxy formation and evolution and the formation of stellar systems and exoplanets. stars form in highly turbulent and magnetized molecular clouds. recent work has shown that self-gravity, turbulence, magnetic fiel... | investigating the impact of stellar feedback on models of star formation |
high resolution alma co (2-1) observations of the ram pressure stripped galaxies ngc 4402 in the virgo cluster, and ngc 4921 in the coma cluster, show some of the clearest evidence yet of the impact of ram pressure on the molecular ism of galaxies. the leading side of ngc 4402, upon which ram pressure is incident, has ... | alma evidence for the direct ram pressure stripping of molecular gas in two cluster galaxies |
bright-rimmed clouds (brcs), which are located at periphery of hii regions, are considered to be potential sites for induced star formation by uv radiation from nearby massive stars. many theorists have developed 2d/3d hydrodynamical models to understand dynamical evolution of such molecular clouds. most simulations, h... | a study of magnetic fields on bright-rimmed clouds |
giant molecular clouds (gmcs) are primary sites of star formation in the present-day universe. although scarce in numbers, newborn massive stars exert a disproportionate influence on the chemistry, dynamics, and structure of natal clouds and the surrounding interstellar medium (ism). in particular, copious ultraviolet ... | dynamical evolution of giant molecular clouds driven by uv radiation feedback from massive stars |
it has been recognized that non-ideal mhd effects (ohmic diffusion, hall effect, ambipolar diffusion) play crucial roles for the circumstellar disk formation and evolution. ohmic and ambipolar diffusion decouple the gas and the magnetic field, and significantly reduces the magnetic torque in the disk, which enables the... | the impact of non-ideal effects on the circumstellar disk evolution and their observational signatures |
we investigate possible driving mechanisms of volcanic activity on large rocky super-earths with masses exceeding four earth masses. due to high pressures in the mantles of these planets, melting in deep mantle layers can be suppressed, even if the energy release due to tidal heating and radioactive decay is substantia... | interior heating by stellar magnetic fields as a driver of volcanic activity on massive rocky planets |
we present the results of the numerical simulations of the collapse of magnetic rotating protostellar clouds with mass 10 m⊙. the hierarchical structure of the cloud formed at the isothermal stage of the collapse is investigated for various initial ratios of the magnetic energy of the cloud to the modulus of its gravit... | influence of the magnetic field on the formation of protostellar disks |
the presence of multiphase gas in the cgm plays an essential role in galactic evolution. specifically, multiphase outflows prevent pristine cosmic gas from accreting onto galaxies, regulating star formation in the disk. yet observations of co-spatial cold and hot outflowing gas are puzzling as the ablation time of the ... | the interplay between radiative cooling and magnetic draping |
current sheets are localized regions of the plasma in which the current density can become singular in the zero-dissipation limit. while the critical role of such structures in mediating fast reconnection and turbulence has been recognized for some time, the universal nature of the plasmoid instability of these structu... | james clerk maxwell prize for plasma physics: current sheets and the plasmoid instability: mediators of fast magnetic reconnection and turbulence |
zonal flows in rotating systems have been previously shown to be suppressed by the imposition of a background magnetic field aligned with the direction of rotation. understanding the physics behind the suppression may be important in systems found in astrophysical fluid dynamics, such as stellar interiors. however, the... | magnetic suppression of zonal flows on a beta plane |
observations of young open clusters have revealedabimodaldistribution of the rotation periods of solar-like starsthathas proven difficult to explain under the existing rubric ofmagnetic braking. recent studies suggest that magneticcomplexity can play an important role incontrollingstellar spin-down rates. in this talk ... | the missing magnetic morphology term in stellar rotation evolution |
the bondi and bondi-hoyle-lytlleton formulas give the order of magnitude steady-accretion rate onto a point mass at rest or moving, respectively, in a uniform density gas in the limit of negligible gas self-gravity. this applies in star-forming clouds where self-gravity is negligible near protostars and new-born stars,... | bondi-like accretion in magnetized supersonic isothermal turbulence |
in this work we will show the difference between stellar wind cavities of typical o and b-type stars and our local heliosphere. in particular we will show the affect of different cooling functions on stellar wind/astrosphere evolution when radiative cooling is taken into account. a study on the effect of an ism magneti... | a comparison between different stellar wind cavities and the heliosphere |
millisecond pulsars (msps) are formed in the accreting binary neutron star systems, while the magnetic fields of msps decays to 10**8 gauss, and spin frequency is spun-up to several milliseconds, after the ns accretes about 0.2 solar masses. the distribution of msp spins imply that gravitational wave (gw) emission limi... | the spin frequency distribution of millisecond pulsar and implication of gravitational wave emission |
the theory of the fossil magnetic field of young stars and their accretion disks has been verified by comparing the observational data with the results of numerical simulations of the collapse of protostellar clouds. a new model of dust evaporation has been proposed, in which the parameter is not the thickness of the m... | effect of dust evaporation on the fossil magnetic field of young stars and their accretion disks |
numerical studies of two-dimensional β-plane homogeneous decaying magnetohydrodynamic turbulence are presented. s tudy of fundamental properties of such turbulence allows understanding the evolution of various astrophysical objects from the sun and stars to planetary systems, galaxies, and galaxy clusters. q ualitative... | inverse and direct energy cascades in two-dimensional β-plane magnetohydrodynamic turbulence |
outflows and winds driven by magnetic fields play an important role in the evolution of protoplanetary disks via the removal of angular momentum and mass. in the context of star and planet formation, it is therefore important to understand how these outflows and winds function under realistic physical conditions. in th... | global non-ideal mhd simulations of protoplanetary disks with irradiation, thermochemistry, and synthetic observations |
magnetospheric accretion of circumstellar disc material is a mechanism that affects a variety of astrophysical objects, from young low-mass stellar objects to compact objects, such as white dwarves and neutron stars. within this picture, the accretion flow in their inner circumstellar disc is channeled along the stella... | mhd protostar-disc interaction. |
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