90 research outputs found

    First imaging spectroscopy observations of solar drift pair bursts

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    Drift pairs are an unusual and puzzling type of fine structure sometimes observed in dynamic spectra of solar radio emission. They appear as two identical short narrowband drifting stripes separated in time; both positive and negative frequency drifts are observed. Currently, due to the lack of imaging observations, there is no satisfactory explanation for this phenomenon. Using the Low Frequency Array (LOFAR), we report unique observations of a cluster of drift pair bursts in the frequency range of 30−70 MHz made on 12 July 2017. Spectral imaging capabilities of the instrument have allowed us for the first time to resolve the temporal and frequency evolution of the source locations and sizes at a fixed frequency and along the drifting pair components. Sources of two components of a drift pair have been imaged and found to propagate in the same direction along nearly the same trajectories. Motion of the second component source is seen to be delayed in time with respect to that of the first one. The source trajectories can be complicated and non-radial; positive and negative frequency drifts correspond to opposite propagation directions. The drift pair bursts with positive and negative frequency drifts, as well as the associated broadband type-III-like bursts, are produced in the same regions. The visible source velocities are variable from zero to a few 104 (up to ∼105) km s−1, which often exceeds the velocities inferred from the drift rate (∼104 km s−1). The visible source sizes are of about 10′−18′; they are more compact than typical type III sources at the same frequencies. The existing models of drift pair bursts cannot adequately explain the observed features. We discuss the key issues that need to be addressed, and in particular the anisotropic scattering of the radio waves. The broadband bursts observed simultaneously with the drift pairs differ in some aspects from common type III bursts and may represent a separate type of emission

    Turbulent kinetic energy in the energy balance of a solar flare

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    The energy released in solar flares derives from a reconfiguration of magnetic fields to a lower energy state, and is manifested in several forms, including bulk kinetic energy of the coronal mass ejection, acceleration of electrons and ions, and enhanced thermal energy that is ultimately radiated away across the electromagnetic spectrum from optical to X-rays. Using an unprecedented set of coordinated observations, from a suite of instruments, we here report on a hitherto largely overlooked energy component -- the kinetic energy associated with small-scale turbulent mass motions. We show that the spatial location of, and timing of the peak in, turbulent kinetic energy together provide persuasive evidence that turbulent energy may play a key role in the transfer of energy in solar flares. Although the kinetic energy of turbulent motions accounts, at any given time, for only \sim (0.5-1)\% of the energy released, its relatively rapid (\sim1-10~s) energization and dissipation causes the associated throughput of energy (i.e., power) to rival that of major components of the released energy in solar flares, and thus presumably in other astrophysical acceleration sites

    Instabilities in the two-dimensional cubic nonlinear Schrodinger equation

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    The two-dimensional cubic nonlinear Schrodinger equation (NLS) can be used as a model of phenomena in physical systems ranging from waves on deep water to pulses in optical fibers. In this paper, we establish that every one-dimensional traveling wave solution of NLS with trivial phase is unstable with respect to some infinitesimal perturbation with two-dimensional structure. If the coefficients of the linear dispersion terms have the same sign then the only unstable perturbations have transverse wavelength longer than a well-defined cut-off. If the coefficients of the linear dispersion terms have opposite signs, then there is no such cut-off and as the wavelength decreases, the maximum growth rate approaches a well-defined limit.Comment: 4 pages, 4 figure

    Angular momenta creation in relativistic electron-positron plasma

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    Creation of angular momentum in a relativistic electron-positron plasma is explored. It is shown that a chain of angular momentum carrying vortices is a robust asymptotic state sustained by the generalized nonlinear Schrodinger equation characteristic to the system. The results may suggest a possible electromagnetic origin of angular momenta when it is applied to the MeV epoch of the early Universe.Comment: 20 pages, 6 figure

    Plan de actividades recreativas utilizando como medio el juego de balonmano adaptado, para los adolescentes entre 12 y 16 años del sexo masculino, de la circunscripción 117 El Batey de Sánchez, del Consejo Popular Las Ovas del municipio Pinar del Río

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    Este trabajo fue realizado en la circunscripción 117 “El Batey de Sánchez”, del Consejo Popular Las Ovas municipio Pinar del Río, el mismo surge debido a la carencia de actividades-físico recreativas destinadas a los adolescentes con edades comprendidas entre 12 y 16 años. Para su realización nos trazamos como problema científico el siguiente: ¿Cómo mejorar la recreación física en los adolescentes entre 12 y 16 años de edad del sexo masculino de la circunscripción 117 “El Batey de Sánchez”, del consejo popular las Ovas? el mismo surge por la problemática que presentan los adolescentes de esta circunscripción, dentro de los cuales podemos mencionar las peleas de gallos, perros, tomeguines, lo cual se pudo comprobar con la aplicación de los diferentes métodos utilizados en nuestro trabajo. Debido a la importancia del mismo nos propusimos el siguiente Objetivo: Aplicar un plan de actividades recreativas utilizando como medio el juego de balonmano adaptado para los adolescentes entre 12 y 16 años de edad del sexo masculino de la circunscripción 117 “El Batey de Sánchez”, del consejo popular Las Ovas municipio Pinar del Rió. Al final del mismo se presentan conclusiones y recomendaciones, las cuales dan respuestas a las interrogantes planteadas al comienz

    United classification of cosmic gamma-ray bursts and their counterparts

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    United classification of gamma-ray bursts and their counterparts is established on the basis of measured characteristics: photon energy E and emission duration T. The founded interrelation between the mentioned characteristics of events consists in that, as the energy increases, the duration decreases (and vice versa). The given interrelation reflects the nature of the phenomenon and forms the E-T diagram, which represents a natural classification of all observed events in the energy range from 10E9 to 10E-6 eV and in the corresponding interval of durations from about 10E-2 up to 10E8 s. The proposed classification results in the consequences, which are principal for the theory and practical study of the phenomenon.Comment: Keywords Gamma rays: burst

    Quantum state-dependent diffusion and multiplicative noise: a microscopic approach

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    The state-dependent diffusion, which concerns the Brownian motion of a particle in inhomogeneous media has been described phenomenologically in a number of ways. Based on a system-reservoir nonlinear coupling model we present a microscopic approach to quantum state-dependent diffusion and multiplicative noise in terms of a quantum Markovian Langevin description and an associated Fokker-Planck equation in position space in the overdamped limit. We examine the thermodynamic consistency and explore the possibility of observing a quantum current, a generic quantum effect, as a consequence of this state-dependent diffusion similar to one proposed by B\"{u}ttiker [Z. Phys. B {\bf 68}, 161 (1987)] in a classical context several years ago.Comment: To be published in Journal of Statistical Physics 28 pages, 3 figure

    Partonic flow and ϕ\phi-meson production in Au+Au collisions at sNN\sqrt{s_{NN}} = 200 GeV

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    We present first measurements of the ϕ\phi-meson elliptic flow (v2(pT)v_{2}(p_{T})) and high statistics pTp_{T} distributions for different centralities from sNN\sqrt{s_{NN}} = 200 GeV Au+Au collisions at RHIC. In minimum bias collisions the v2v_{2} of the ϕ\phi meson is consistent with the trend observed for mesons. The ratio of the yields of the Ω\Omega to those of the ϕ\phi as a function of transverse momentum is consistent with a model based on the recombination of thermal ss quarks up to pT4p_{T}\sim 4 GeV/cc, but disagrees at higher momenta. The nuclear modification factor (RCPR_{CP}) of ϕ\phi follows the trend observed in the KS0K^{0}_{S} mesons rather than in Λ\Lambda baryons, supporting baryon-meson scaling. Since ϕ\phi-mesons are made via coalescence of seemingly thermalized ss quarks in central Au+Au collisions, the observations imply hot and dense matter with partonic collectivity has been formed at RHIC.Comment: 6 pages, 4 figures, submit to PR
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