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massive stars, multiple stellar systems, and clusters are born of the gravitational collapse of massive, dense, gaseous clumps, and the way these systems form strongly depends on how the parent clump fragments into cores during collapse. numerical simulations show that magnetic fields may be the key ingredient in regul... | magnetically regulated fragmentation of a massive, dense, and turbulent clump |
polarized magnetic dipole (m1) emission lines provide important diagnostics for the magnetic field dominating the evolution of the solar corona. this paper advances a multi-line technique using specific combinations of m1 lines to infer the full vector magnetic field for regions of optically thin emission that can be l... | using multi-line spectropolarimetric observations of forbidden emission lines to measure single-point coronal magnetic fields |
we present scexao/charis 1.1-2.4 μm integral field direct spectroscopy of the young hip 79124 triple system. hip 79124 is a member of the scorpius-centaurus association, consisting of an a0v primary with two low-mass companions at a projected separation of < 1″. thanks to the high quality wavefront corrections provi... | isochronal age-mass discrepancy of young stars: scexao/charis integral field spectroscopy of the hip 79124 triple system |
in this paper, we present steady-state relativistic magnetohydrodynamic simulations that include a mass-load term to study the process of jet deceleration. the mass load mimics the injection of a proton-electron plasma from stellar winds within the host galaxy into initially pair plasma jets, with mean stellar mass-los... | on the deceleration of fanaroff-riley class i jets: mass loading of magnetized jets by stellar winds |
we have studied the filaments extracted from the column density maps of the nearby lupus 1, 3, and 4 molecular clouds, derived from photometric maps observed with the herschel satellite. filaments in the lupus clouds have quite low column densities, with a median value of ∼1.5 × 1021 cm-2 and most have masses per unit ... | filaments in the lupus molecular clouds |
we consider the existence of a neutron star magnetic field by the detected cyclotron lines. we collected data on nine sources of high-mass x-ray binaries with supergiant companions as a test case for our model, to demonstrate their distribution and evolution. the wind velocity, spin period and magnetic field strength a... | on the possibility of disk-fed formation in supergiant high-mass x-ray binaries |
the paper presents magnetic field measurements for 15 chemically peculiar (cp) stars of subgroup 1b in the orion ob1 association. we have found that the proportion of stars with strong magnetic fields among these 15 cp stars is almost twice as large as in subgroup 1a. along with this, the age of subgroup 1b is estimate... | magnetic fields of cp stars in the orion ob1 association. iv. stars of subgroup 1b |
particle-accelerating colliding-wind binaries (pacwbs) are multiple systems made of early-type stars able to accelerate particles up to relativistic velocities. the relativistic particles can interact with different fields (magnetic or radiation) in the colliding-wind region and produce non-thermal emission. in many ca... | an investigation into the fraction of particle accelerators among colliding-wind binaries. towards an extension of the catalogue |
we assess the systematic uncertainties in stellar evolutionary calculations for low- to intermediate-mass, main-sequence stars. we compare published stellar tracks from several different evolution codes with our own tracks computed using the stellar codes stars and mesa. in particular, we focus on tracks of 1 and 3 m⊙ ... | confronting uncertainties in stellar physics. ii. exploring differences in main-sequence stellar evolution tracks |
we summarize the results of a dedicated effort made between 2012 and 2019 to follow the evolution of the cyclotron line in her x-1 through repeated nustar observations. the previously observed nearly 20-year-long decay of the cyclotron line energy has ended in 2012: from then on, the pulse-phase-averaged flux-corrected... | cyclotron line energy in hercules x-1: stable after the decay |
context. surface differential rotation (dr) is one major ingredient of the magnetic field generation process in the sun and likely in other stars. the term solar-like differential rotation describes the observation that solar equatorial regions rotate faster than polar ones. the opposite effect of polar regions rotatin... | discriminating solar and antisolar differential rotation in high-precision light curves |
it has been suggested that the absence of macroturbulence in the atmosphere of ngc 1624-2 is due its strong magnetic field (the strongest known for a massive o star) suppressing convection in its outer layers, removing the mechanism thought responsible for the observed macroturbulence in stars with lower field strength... | magnetic inhibition of convection in o-star envelopes |
in the context of the high resolution, high signal-to-noise ratio, high sensitivity, spectropolarimetric survey britepol, which complements observations by the brite constellation of nanosatellites for asteroseismology, we are looking for and measuring the magnetic field of all stars brighter than v = 4. in this paper,... | discovery of magnetic a supergiants: the descendants of magnetic main-sequence b stars |
the hosking integral, which characterizes magnetic helicity fluctuations in subvolumes, is known to govern the decay of magnetically dominated turbulence. here, we show that, when the evolution of the magnetic field is controlled by the motion of electrons only, as in neutron star crusts, the decay of the magnetic fiel... | hosking integral in non-helical hall cascade |
large-scale magnetic fields play a vital role in determining the angular momentum transport and generating jets/outflows in accreting systems, yet their origins remain poorly understood. we focus on radiatively inefficient accretion flows (riafs) around black holes (bhs), and conduct 3d general-relativistic magnetohydr... | magnetic flux transport in radiatively inefficient accretion flows and the pathway toward a magnetically arrested disk |
we develop new angular momentum evolution models for stars with masses of 0.5 to 1.6 m⊙ and from the pre-main-sequence (pms) through the end of their main-sequence (ms) lifetime. the parametric models include magnetic braking based on numerical simulations of magnetized stellar winds, mass-loss-rate prescription, core-... | a semi-empirical model for magnetic braking of solar-type stars |
we analyze nonlinear evolution of torsional alfvén waves in a straight magnetic flux tube filled in with a low-β plasma, and surrounded with a plasma of lower density. such magnetic tubes model, in particular, a segment of a coronal loop or a polar plume. the wavelength is taken comparable to the tube radius. we perfor... | nonlinear evolution of short-wavelength torsional alfvén waves |
magnetic activity of stars like the sun evolves in time because of spin-down owing to angular momentum removal by a magnetized stellar wind. these magnetic fields are generated by an internal dynamo driven by convection and differential rotation. spin-down therefore converges at an age of about 700 myr for solar-mass s... | the sun through time |
although galactic outflows play a key role in our understanding of the evolution of galaxies, the exact mechanism by which galactic outflows are driven is still far from being understood and, therefore, our understanding of associated feedback mechanisms that control the evolution of galaxies is still plagued by many e... | driving galactic outflows with magnetic fields at low and high redshift |
this paper describes 3d simulations of the formation of collapsing cold clumps via thermal instability inside a larger cloud complex. the initial condition was a diffuse atomic, stationary, thermally unstable, 200 pc diameter spherical cloud in pressure equilibrium with low-density surroundings. this was seeded with 10... | sheets, filaments, and clumps - high-resolution simulations of how the thermal instability can form molecular clouds |
most massive galaxies are thought to contain a supermassive black hole in their centre surrounded by a tenuous gas environment, leading to no significant emission. in these quiescent galaxies, tidal disruption events represent a powerful detection method for the central black hole. following the disruption, the stellar... | bad prospects for the detection of giant stars' tidal disruption: effect of the ambient medium on bound debris |
we report the evolution of the x-ray pulsations of exo 2030+375 during its 2021 outburst using the observations from insight-hxmt. based on the accretion torque model, we study the correlation between the spin frequency derivatives and the luminosity. pulsations can be detected in the energy band of 1-160 kev. the puls... | timing analysis of exo 2030+375 during its 2021 giant outburst observed with insight-hxmt |
seismic and magnetic observations have suggested the presence of a stably stratified layer atop earth's core. such a layer could affect the morphology of the geomagnetic field and the evolution of the core, but the precise impact of this layer depends largely on its internal dynamics. among other physical phenomena, st... | internal gravity waves in a stratified layer atop a convecting liquid core in a non-rotating spherical shell |
the role of magnetic fields in galaxy evolution is still an unsolved question in astrophysics. we have previously shown that magnetic fields play a crucial role in major mergers between disc galaxies; in hydrodynamic simulations of such mergers, the auriga model produces compact remnants with a distinctive bar and ring... | the impact of magnetic fields on cosmological galaxy mergers - ii. modified angular momentum transport and feedback |
short gamma-ray bursts that are followed by long-duration x-ray plateaus may be powered by the birth, and hydrodynamic evolution, of magnetars from compact binary coalescence events. if the rotation and magnetic axes of the system are not orthogonal to each other, the star will undergo free precession, leading to fluct... | precessing magnetars as central engines in short gamma-ray bursts |
we study the four-dimensional relationships between magnetic activity, rotation, mass, and age for solar-type stars in the age range 5-25 myr. this is the late-pre-main-sequence (l-pms) evolutionary phase when rapid changes in a star's interior may lead to changes in the magnetic dynamo mechanisms. we carefully derive ... | magnetic activity-rotation-age-mass relations in late-pre-main-sequence stars |
with forty years since the discovery of the first cyclotron line in her x-1, there have been remarkable advancements in the field related to the study of the physics of accreting neutron stars - cyclotron lines have been a major torchbearer in this regard, from being the only direct estimator of the magnetic field stre... | cyclotron lines: from magnetic field strength estimators to geometry tracers in neutron stars |
a high-resolution spectropolarimetric survey of all (573) stars brighter than magnitude v= 4 has been undertaken with narval at tbl, espadons at cfht, and harpspol at eso, as a ground-based support to the brite constellation of nano-satellites in the framework of the ground-based observing team (gbot). the goal is to d... | the brite spectropolarimetric program |
context. runaway stars produce bowshocks that are usually observed at infrared (ir) wavelengths. non-thermal radio emission has been detected so far only from the bowshock of bd+43°3654, whereas the detection of non-thermal radiation from these bowshocks at high energies remains elusive.aims: we aim at characterising i... | multi-zone non-thermal radiative model for stellar bowshocks |
context. magnetic fields can significantly affect the star formation process. the theory of the magnetically driven collapse in a uniform field predicts that the contraction initially happens along the field lines. when the gravitational pull grows strong enough, the magnetic field lines pinch inwards, giving rise to a... | magnetic properties of the protostellar core iras 15398-3359 |
the evolution of the gravitational-wave phase in the signal produced by inspiralling binaries of compact stars is modified by the nonzero deformability of the two stars. hence, the measurement of these corrections has the potential of providing important information on the equation of state of nuclear matter. extensive... | tidal deformability and gravitational-wave phase evolution of magnetized compact-star binaries |
our understanding of large-scale magnetic fields in stellar radiative zones remains fragmented and incomplete. such magnetic fields, which must be produced by some form of dynamo mechanism, are thought to dominate angular-momentum transport, making them crucial to stellar evolution. a major difficulty is the effect of ... | on large-scale dynamos with stable stratification and the application to stellar radiative zones |
insufficient numerical resolution of grid-based, direct numerical simulations (dns) hampers the development of instability-driven turbulence at small (unresolved) scales. as an alternative to dns, sub-grid models can potentially reproduce the effects of turbulence at small scales in terms of the resolved scales, and he... | assessment of a new sub-grid model for magnetohydrodynamical turbulence. i. magnetorotational instability |
we present the analysis of the brightest flare that was recorded in the insight-hmxt data set in a broad energy range (2-200 kev) from the microquasar grs 1915+105 during an unusual low-luminosity state. this flare was detected by insight-hxmt among a series of flares during 2019 june 2 utc 16:37:06-20:11:36 with a 2-2... | insight-hxmt observations of a possible fast transition from the jet- to wind-dominated state during a huge flare of grs 1915+105 |
deep r-band ccd linear polarimetry collected for fields with lines of sight toward the lupus i molecular cloud is used to investigate the properties of the magnetic field within this molecular cloud. the observed sample contains about 7000 stars, almost 2000 of them with a polarization signal-to-noise ratio larger than... | tracing the magnetic field morphology of the lupus i molecular cloud |
the geomagnetic field has been continuously monitored from low-earth orbit (leo) since 1999, complementing ground-based observatory data by providing calibrated scalar and vector measurements with global coverage. the successful three-satellite esa swarm constellation is expected to remain in operation up to at least 2... | nanomagsat, a 16u nanosatellite constellation high-precision magnetic project to initiate permanent low-cost monitoring of the earth's magnetic field and ionospheric environment |
context. dwarf novæ (dne) and low mass x-ray binaries (lmxbs) show eruptions that are thought to be due to a thermal-viscous instability in their accretion disk. these eruptions provide constraints on angular momentum transport mechanisms.aims: we explore the idea that angular momentum transport could be controlled by ... | magnetic field transport in compact binaries |
stellar winds govern the angular momentum evolution of solar-like stars throughout their main-sequence lifetime. the efficiency of this process depends on the geometry of the star's magnetic field. there has been a rapid increase recently in the number of stars for which this geometry can be determined through spectrop... | estimating stellar wind parameters from low-resolution magnetograms |
planck galactic cold clumps (pgccs) possibly represent the early stages of star formation. to understand better the properties of pgccs, we studied 16 pgccs in the l1495 cloud with molecular lines and continuum data from herschel, jcmt/scuba-2, and the pmo 13.7 m telescope. thirty dense cores were identified in 16 pgcc... | the properties of planck galactic cold clumps in the l1495 dark cloud |
context. the solar dynamo consists of a process that converts poloidal magnetic field to toroidal magnetic field followed by a process that creates new poloidal field from the toroidal field.aims: our aim is to observe the poloidal and toroidal fields relevant to the global solar dynamo and to see if their evolution is... | observing and modeling the poloidal and toroidal fields of the solar dynamo |
sgr j1745-2900 was detected from its outburst activity in 2013 april and it was the first soft gamma repeater (sgr) detected near the center of the galaxy (sagittarius a*). we use 3.5 yr chandra x-ray light-curve data to constrain some neutron star (ns) geometric parameters. we assume that the flux modulation comes fro... | evidence for a multipolar magnetic field in sgr j1745-2900 from x-ray light-curve analysis |
short gamma-ray bursts (grbs) are presumably results of binary neutron star mergers, which lead to the formation of a stellar mass black hole, surrounded by remnant matter. the strong magnetic fields help collimate jets of plasma, launched along the axis of the black hole rotation. we study the structure and evolution ... | the mri imprint on the short-grb jets |
how the accreted mass settling on the surface of a neutron star affects the topology of the magnetic field and how the secular evolution of the binary system depends on the magnetic field change is still an open issue. we report evidence for a clear drop in the observed magnetic field in the accreting pulsar v0332+53 a... | an unexpected drop in the magnetic field of the x-ray pulsar v0332+53 after the bright outburst occurred in 2015 |
context. the origin of fossil fields in intermediate- and high-mass stars is poorly understood, as is the interplay between binarity and magnetism during stellar evolution. thus we have begun a study of the magnetic properties of a sample of intermediate-mass and massive short-period binary systems as a function of bin... | the magnetic field of the double-lined spectroscopic binary system hd 5550 |
context. recently, the colliding-wind region of the binary stellar system hd 93129a was resolved for the first time using very large baseline interferometry. this system, one of the most massive known binaries in our galaxy, presents non-thermal emission in the radio band, which can be used to infer the physical condit... | a model for the non-thermal emission of the very massive colliding-wind binary hd 93129a |
the theoretical prediction that magnetic reconnection spontaneously drives turbulence has been supported by magnetohydrodynamic (mhd) and kinetic simulations. while reconnection with externally driven turbulence is accepted as an effective mechanism for particle acceleration, the acceleration during the reconnection wi... | particle acceleration in self-driven turbulent reconnection |
a glitch of a pulsar is known as a sudden increase in the spin frequency and spin-down rate (frequency time derivative), and it can be caused by a sudden release of the stress built up in the solid crust of the star or pinned vortices in the superfluid interior. psr j2021+4026 is the first pulsar that shows a significa... | mode change of a gamma-ray pulsar, psr j2021+4026 |
we study the magneto-rotational instability (mri) driven dynamo in a geometrically thin disc ($h/r\ll 1$) using stratified zero net flux (znf) shearing box simulations. we find that mean fields and emfs oscillate with a primary frequency $f_{\rm dyn} = 0.017$ ($\approx 9$ orbital period), but also have higher harmonics... | shedding light on the mri driven dynamo in a stratified shearing box |
context. the properties and evolution of magnetic fields surrounding galaxies are observationally largely unconstrained. the detection and study of these magnetic fields is important to understand galaxy evolution since magnetic fields are tracers for dynamical processes in the circumgalactic medium (cgm) and can have ... | probing magnetic fields in the circumgalactic medium using polarization data from mightee |
when the accreting white dwarf in a magnetic cataclysmic variable star (mcv) has a field strength in excess of 10 mg, it is expected to synchronize its rotational frequency to the binary orbit frequency, particularly at small binary separations, due to the steep radial dependence of the magnetic field. we report the di... | sdss j134441.83+204408.3: a highly asynchronous short-period magnetic cataclysmic variable with a 56 mg field strength |
plaskett's 'star' appears to be one of a small number of short-period binary systems known to contain a hot, massive, magnetic star. we combine an extensive spectropolarimetric (stokes v) data set with archival photometry and spectropolarimetry to establish the essential characteristics of the magnetic field and magnet... | the magnetic field and magnetosphere of plaskett's star: a fundamental shift in our understanding of the system |
the first multimessenger observation attributed to a merging neutron star binary provided an enormous amount of observational data. unlocking the full potential of this data requires a better understanding of the merger process and the early postmerger phase, which are crucial for the later evolution that eventually le... | numerical inside view of hypermassive remnant models for gw170817 |
ρ pup is a δ scuti f2 pulsator, known to host a main radial mode as well as non-radial pulsations, with chemical peculiarities typical of evolved am stars. we present a high-precision spectropolarimetric observations of this star, obtained with espadons at the canada-france-hawaii telescope in the frame of the brite sp... | discovery of a magnetic field in the δ scuti f2m star ρ pup |
sharp phase transitions allow for the existence of a third family of stable compact stars, twin stars. in this work, we investigate for the first time the role of strong magnetic fields on non-magnetic twin-star sequences and the case in which magnetic fields themselves give rise to a third family of stable stars. we u... | can magnetic fields (de)stabilize twin stars? |
the spectral anisotropy of turbulent structures has been measured in the solar wind since 1990, relying on the assumption of axisymmetry about the mean magnetic field, b 0. however, several works indicate that this hypothesis might be partially wrong, thus raising two questions: (i) is it correct to interpret measureme... | beyond the maltese cross: geometry of turbulence between 0.2 and 1 au |
this paper presents detailed consideration of methodologies to calibrate differential light curves for accurate physical starspot modeling. we use the sun and starspot models as a testbed to highlight some factors in this calibration that that have not yet been treated with care. one unambiguously successful procedure ... | calibration of differential light curves for physical analysis of starspots |
late-type main-sequence stars exhibit an x-ray to bolometric flux ratio that depends on {tilde{r}o}, the ratio of rotation period to convective turnover time, as {tilde{r}o}^{-ζ } with 2 ≤ ζ ≤ 3 for {tilde{r}o} > 0.13, but saturates with |ζ| < 0.2 for {tilde{r}o} < 0.13. saturated stars are younger than unsatu... | minimalist coupled evolution model for stellar x-ray activity, rotation, mass loss, and magnetic field |
this review has two parts. the first one is devoted to the barbier–chalonge–divan (bcd) spectrophotometric system, also known as the paris spectral classification system. although the bcd system has been applied and is still used for all stellar objects from o to f spectral types, the present account mainly concerns no... | bcd spectrophotometry and rotation of active b-type stars: theory and observations |
despite their rarity, massive stars dominate the ecology of galaxies via their strong, radiatively-driven winds throughout their lives and as supernovae in their deaths. however, their evolution and subsequent impact on their environment can be significantly affected by the presence of a magnetic field. while recent st... | a search for strong magnetic fields in massive and very massive stars in the magellanic clouds |
the magnetic field structure, kinematical stability, and evolutionary status of the starless dense core barnard 68 (b68) are revealed based on the near-infrared polarimetric observations of background stars, measuring the dichroically polarized light produced by aligned dust grains in the core. after subtracting unrela... | distortion of magnetic fields in barnard 68 |
blue stragglers and other mass transfer/collision products are likely born with rapid rotation rates due to angular momentum transfer during mass-transfer, merger, or collisional formation. however, less is known about the angular momentum evolution of these stars as they age. here we compare rotation rates and post-fo... | observations of spin-down in post-mass-transfer stars and the possibility for blue straggler gyrochronology |
context. stars and their winds can contribute to the non-thermal emission in extragalactic jets. because of the complexity of jet-star interactions, the properties of the resulting emission are closely linked to those of the emitting flows.aims: we simulate the interaction between a stellar wind and a relativistic extr... | coupling hydrodynamics and radiation calculations for star-jet interactions in active galactic nuclei |
mhd turbulence is common in many space physics and astrophysics environments. we first discuss the properties of incompressible mhd turbulence. a well-conductive fluid amplifies initial magnetic fields in a process called small-scale dynamo. below equipartition scale for kinetic and magnetic energies the spectrum is st... | mhd turbulence, turbulent dynamo and applications |
a precondition for the radio emission of pulsars is the existence of strong, small-scale magnetic field structures (`magnetic spots') in the polar cap region. their creation can proceed via crustal hall drift out of two qualitatively and quantitatively different initial magnetic field configurations: a field confined c... | gravitational radiation from neutron stars deformed by crustal hall drift |
optical, j and k photometric observations of the kv uma black hole x-ray nova in its quiescent state obtained in 2017-2018 are presented. a significant flickering within light curves was not detected, although the average brightness of the system faded by ≈0.1m over 350 d. changes in the average brightness were not acc... | optical, j and k light curves of xte j1118+480 = kv uma: the mass of the black hole and the spectrum of the non-stellar component |
the origin and evolution of the 1/f power law observed in the energy spectrum of solar coronal and solar wind fluctuations at scales of around an hour is not entirely understood. several existing theories aim at explaining it, involving both linear and nonlinear mechanisms. an often overlooked property of the solar cor... | phase mixing and the 1/f spectrum in the solar wind |
a fireball of radiation plasma created near the surface of a neutron star (ns) expands under its own pressure along magnetic field lines, and produces photon emission and relativistic matter outflow. we comprehensively classify the expanding fireball evolution into five cases, and obtain the photospheric luminosity and... | expanding fireball in magnetar bursts and fast radio bursts |
context. the spin evolution of young protostars, surrounded by an accretion disk, still poses problems for observations and theoretical models. in recent studies, the importance of the magnetic star-disk interaction for stellar spin evolution has been elaborated. the accretion disk in these studies, however, is only re... | time-dependent, long-term hydrodynamic simulations of the inner protoplanetary disk. ii. the importance of stellar rotation |
we numerically investigate the dynamics of a supernova fallback accretion confronting with a relativistic wind from a newborn neutron star (ns). the time evolution of the accretion shock in the radial direction is basically characterized by the encounter radius of the flow renc and a dimensionless parameter $\zeta \equ... | a necessary condition for supernova fallback invading newborn neutron-star magnetosphere |
the orion nebula is a prime example of a massive star-forming region in our galaxy. observations have shown that gravitational and magnetic energy are comparable in its integral-shaped filament on a scale of ∼1 pc, and that the population of pre-main sequence stars appears dynamically heated compared to the protostars.... | magnetic tension and instabilities in the orion a integral-shaped filament |
we examine the effects of plastic flow that appear in a neutron-star crust when a magnetic stress exceeds the threshold. the dynamics involved are described using the navier-stokes equation comprising the viscous-flow term, and the velocity fields for the global circulation are determined using quasi-stationary approxi... | magnetic-field evolution with large-scale velocity circulation in a neutron-star crust |
understanding the origin of stellar masses—the initial mass function (imf)— remains one of the most challenging problems in astrophysics. the imf is a key ingredient for simulations of galaxy formation and evolution, and is used to calibrate star formation relations in extra-galactic observations. modeling the imf dire... | converging on the initial mass function of stars |
the rapidly evolving dust and gas extinction observed towards wd 1145+017 has opened a real-time window on to the mechanisms for destruction-accretion of planetary bodies on to white dwarf stars, and has served to underline the importance of considering the dynamics of dust particles around such objects. here it is arg... | magnetospherically-trapped dust and a possible model for the unusual transits at wd 1145+017 |
eccentric binaries known as heartbeat stars experience strong dynamical tides as the stars pass through periastron, providing a laboratory to study tidal interactions. we measure the rotation periods of 24 heartbeat systems, using the kepler light curves to identify rotation peaks in the fourier transform. where possib... | the pseudosynchronization of binary stars undergoing strong tidal interactions |
we discuss the spectral and timing properties of the accreting millisecond x-ray pulsar swift j1756.9-2508 observed by xmm-newton, nicer, and nustar during the x-ray outburst occurred in april 2018. the spectral properties of the source are consistent with a hard state dominated at high energies by a non-thermal power-... | swift j1756.9-2508: spectral and timing properties of its 2018 outburst |
context. mass-loss rate is one of the most important stellar parameters. mass loss via stellar winds may influence stellar evolution and modifies stellar spectrum. stellar winds of subluminous hot stars, especially subdwarfs, have not been studied thoroughly.aims: we aim to provide mass-loss rates as a function of subd... | stellar wind models of subluminous hot stars |
context. alma observations at 1.4 mm and ~0."2 (~750 au) angular resolution of the main core in the high-mass star-forming region g31.41+0.31 have revealed a puzzling scenario. on the one hand, the continuum emission looks very homogeneous and the core appears to undergo solid-body rotation, suggesting a monolithic cor... | fragmentation in the massive g31.41+0.31 protocluster |
we present the evolution of the x-ray emission properties of the magnetar 1e 1547.0-5408 since february 2004 over a time period covering three outbursts. we analyzed new and archival observations taken with the swift, nustar, chandra, and xmm-newton x-ray satellites. the source has been observed at a relatively steady ... | the long-term enhanced brightness of the magnetar 1e 1547.0-5408 |
we study the behaviour of the cyclotron resonant scattering feature (crsf) of the high-mass x-ray binary vela x-1 using the long-term hard x-ray monitoring performed by the burst alert telescope (bat) on board swift. high-statistics, intensity-selected spectra were built along 11 years of bat survey. while the fundamen... | the swift-bat monitoring reveals a long-term decay of the cyclotron line energy in vela x-1 |
the presence of ultrahigh excitation (uhe) absorption lines (e.g. o viii) in the optical spectra of several of the hottest white dwarfs poses a decades-long mystery and is something that has never been observed in any other astrophysical object. the occurrence of such features requires a dense environment with temperat... | unravelling the baffling mystery of the ultrahot wind phenomenon in white dwarfs |
magnetorotational instability (mri) is the most likely mechanism for angular momentum transport in accretion disks. however, despite numerous efforts, the quest for an unambiguous identification of mri in laboratory is still ongoing. for this purpose, a big taylor-couette experiment with liquid sodium is currently unde... | non-axisymmetric standard magnetorotational instability in the upcoming dresdyn-mri experiments -- linear and nonlinear dynamics |
the evolutions of a neutron star's rotation and magnetic field (b-field) have remained unsolved puzzles for over half a century. we ascribe the rotational braking torques of pulsar to both components, the standard magnetic dipole radiation (mdr) and particle wind flow (mdr + wind, hereafter named mdrw), which we apply ... | evolution of spin period and magnetic field of the crab pulsar: decay of the braking index by the particle wind flow torque |
in this work, we study the effects of magnetic fields and rotation on the structure and composition of proto-neutron stars. a hadronic chiral su(3) model is applied to cold neutron stars and proto-neutron stars with trapped neutrinos and at fixed entropy per baryon. we obtain general relativistic solutions for neutron ... | internal composition of proto-neutron stars under strong magnetic fields |
we report the first clear detection of the zeeman splitting of a ccs emission line at 45 ghz toward the nearby pre-stellar dense filament, taurus molecular cloud 1 (tmc-1). we observed hc_3n non-zeeman lines simultaneously with the ccs line, and did not detect any significant splitting of the hc_3n lines. thus, we conc... | first clear detection of the ccs zeeman splitting toward the pre-stellar core, taurus molecular cloud 1 |
magnetorotational instability (mri) is considered as the most likely mechanism driving angular momentum transport in astrophysical disks. however, despite many efforts, a direct and conclusive experimental evidence of mri in laboratory is still missing. recently performing one-dimensional linear analysis of the standar... | nonlinear evolution of magnetorotational instability in a magnetized taylor-couette flow: scaling properties and relation to upcoming dresdyn-mri experiment |
ar scorpii is an intermediate polar binary system composed of a magnetic white dwarf (wd) and an m-type star and shows nonthermal, pulsed, and highly linearly polarized emission. the radio/optical emission modulates with the wd’s spin and shows the double-peak structure in the light curves. in this paper, we discuss a ... | a model for ar scorpii: emission from relativistic electrons trapped by closed magnetic field lines of magnetic white dwarfs |
context. differential rotation has a strong influence on stellar internal dynamics and evolution, notably by triggering hydrodynamical instabilities, by interacting with the magnetic field, and more generally by inducing transport of angular momentum and chemical elements. moreover, it modifies the way waves propagate ... | asymptotic theory of gravity modes in rotating stars. ii. impact of general differential rotation |
the properties of supersonic isothermal turbulence influence a variety of astrophysical phenomena, including the structure and evolution of star-forming clouds. this work presents a simple model for the structure of dense regions in turbulence in which the density distribution behind isothermal shocks originates from r... | dense regions in supersonic isothermal turbulence |
rotation periods from kepler k2 are combined with projected rotation velocities from the wiyn 3.5 m telescope to determine projected radii for fast-rotating, low-mass (0.15 ≤ m/ m_{⊙ } ≤ 0.6) members of the praesepe cluster. a maximum likelihood analysis that accounts for observational uncertainties, binarity, and cens... | a search for radius inflation among active m-dwarfs in praesepe |
context. we study the time-resolved spectral properties of energetic gamma-ray bursts (grbs) with good high-energy photon statistics observed by the gamma-ray burst monitor (gbm) onboard the fermi gamma-ray space telescope.aims: we aim to constrain in detail the spectral properties of grb prompt emission on a time-reso... | synchrotron cooling in energetic gamma-ray bursts observed by the fermi gamma-ray burst monitor |
the x-ray transient xte j1701-462 was the first source observed to evolve through all known subclasses of low-magnetic-field neutron star low-mass x-ray binaries (ns-lmxbs), as a result of large changes in its mass accretion rate. to investigate to what extent similar evolution is seen in other ns-lmxbs we have perform... | common patterns in the evolution between the luminous neutron star low-mass x-ray binary subclasses |
magnetars are highly magnetized rotating neutron stars that are predominantly observed as high-energy sources. six of this class of neutron star are known to also emit radio emission, so magnetars are a favoured model for the origin of at least some of the fast radio bursts (frbs). if magnetars, or neutron stars in gen... | quasi-periodic sub-pulse structure as a unifying feature for radio-emitting neutron stars |
we study the long-term quasi-steady evolution of the force-free magnetosphere of a magnetar coupled to its internal magnetic field. we find that magnetospheric currents can be maintained on long time-scales of the order of thousands of years. meanwhile, the energy, helicity and twist stored in the magnetosphere all gra... | long-term evolution of the force-free twisted magnetosphere of a magnetar |
we report on two nustar observations of the high-mass x-ray binary a 0535+26 taken toward the end of its normal 2015 outburst at very low 3-50 kev luminosities of 1.4 × 1036 erg s-1 and 5 × 1035 erg s-1, which are complemented by nine swift observations. the data clearly confirm indications seen in earlier data that th... | looking at a 0535+26 at low luminosities with nustar |
a theory of potential vorticity (pv) mixing in a disordered (tangled) magnetic field is presented. the analysis is in the context of β-plane mhd, with a special focus on the physics of momentum transport in the stably stratified, quasi-2d solar tachocline. a physical picture of mean pv evolution by vorticity advection ... | potential vorticity mixing in a tangled magnetic field |
angular momentum is a key property regulating star formation and evolution. however, the physics driving the distribution of the stellar rotation rates of early-type main-sequence stars is as yet poorly understood. using our catalog of 40,034 early-type stars with homogeneous $v\sin i$ parameters, we review the statist... | exploring the stellar rotation of early-type stars in the lamost medium-resolution survey. ii. statistics |
using physics-informed neural networks (pinns) to solve a specific boundary value problem is becoming more popular as an alternative to traditional methods. however, depending on the specific problem, they could be computationally expensive and potentially less accurate. the functionality of pinns for real-world physic... | modelling force-free neutron star magnetospheres using physics-informed neural networks |
we present a first 3d magnetohydrodynamic (mhd) simulation of oxygen, neon, and carbon shell burning in a rapidly rotating $16\hbox{-}\mathrm{m}_\odot$ core-collapse supernova progenitor. we also run a purely hydrodynamic simulation for comparison. after $\mathord \approx 180\mathrm{s}$ ($\mathord \approx$ 15 and 7 con... | 3d simulations of magnetoconvection in a rapidly rotating supernova progenitor |
the bright nova cygni 1975 is a rare nova on a magnetic white dwarf (wd). later it was found to be an asynchronous polar, now called v1500 cyg. our multisite photometric campaign occurring 40 yr post eruption covered 26 nights (2015-2017). the reflection effect from the heated donor has decreased but still dominates th... | asynchronous polar v1500 cyg: orbital, spin, and beat periods |
context. determining the effects of an accretion disk is crucial to understanding the evolution of young stars. during the combined evolution, stellar and disk parameters influence one another, which motivated us to develop a combined stellar and disk model. this makes a combined numerical model, with the disk evolving... | the influence of metallicity on a combined stellar and disk evolution |
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