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Phase-mixing of Alfv\'en waves in the solar corona has been identified as one possible candidate to explain coronal heating. While this scenario is supported by observations of ubiquitous oscillations in the corona carrying sufficient wave…

太阳与恒星天体物理 · 物理学 2017-05-17 Paolo Pagano , Ineke De Moortel

The solar atmosphere may be heated by Alfven waves that propagate up from the convection zone and dissipate their energy in the chromosphere and corona. To further test this theory, we consider wave heating in an active region observed on…

太阳与恒星天体物理 · 物理学 2015-06-16 M. Asgari-Targhi , A. A. van Ballegooijen , S. R. Cranmer , E. E. DeLuca

Interaction of Alfven waves with plasma inhomogeneities generates phase mixing which can lead to dissipate Alfven waves and to heat the solar plasma. Here we study the dissipation of Alfven waves by phase mixing due to viscosity and…

太阳与恒星天体物理 · 物理学 2015-06-18 Z. Fazel , H. Ebadi

Using high resolution cosmological simulations, we study hydrogen and helium gravitational cooling radiation. We focus on the HeII cooling lines, which arise from gas with a different temperature history (T_max ~ 10^5K) than HI line…

With first-principles kinetic simulations, we show that a large-scale Alfv\'en wave (AW) propagating in an inhomogeneous background decays into kinetic Alfv\'en waves (KAWs), triggering ion and electron energization. We demonstrate that the…

等离子体物理 · 物理学 2022-04-27 Fabio Bacchini , Francesco Pucci , Francesco Malara , Giovanni Lapenta

Context: This paper investigates the effectiveness of phase mixing as a coronal heating mechanism. A key quantity is the wave damping rate, $\gamma$, defined as the ratio of the heating rate to the wave energy. Aims: We investigate whether…

太阳与恒星天体物理 · 物理学 2019-12-11 A. P. K. Prokopyszyn , A. W. Hood

The Alfven wave is analyzed in case of one quasineutral plasma propagating with some constant speed $v_0$ through another static quasineutral plasma. A dispersion equation is derived describing the Alfven wave coupled with the flow driven…

等离子体物理 · 物理学 2015-10-20 J. Vranjes

Particle heating in advection-dominated accretion flows (ADAFs) by nonlinear MHD (Alfvenic) turbulence is investigated. Such turbulence with highly-fluctuating magnetic fields, $\tilde B\sim B_0$, is believed to be naturally produced by the…

天体物理学 · 物理学 2015-06-24 Mikhail V. Medvedev

In this paper we further develop a model for the heating of coronal loops by Alfven wave turbulence (AWT). The Alfven waves are assumed to be launched from a collection of kilogauss flux tubes in the photosphere at the two ends of the loop.…

太阳与恒星天体物理 · 物理学 2017-11-08 Adriaan A. van Ballegooijen , Mahboubeh Asgari-Targhi , Alexander Voss

Alfven waves have been invoked as an important mechanism of particle acceleration in stellar winds of cool stars. After their identification in the solar wind they started to be studied in winds of stars located in different regions of the…

太阳与恒星天体物理 · 物理学 2014-11-18 A. A. Vidotto , V. Jatenco-Pereira

We study the propagation, reflection, and turbulent dissipation of Alfven waves in coronal holes and the solar wind. We start with the Heinemann-Olbert equations, which describe non-compressive magnetohydrodynamic fluctuations in an…

太阳与恒星天体物理 · 物理学 2014-11-20 Benjamin D. G. Chandran , Joseph V. Hollweg

The Alfv\'en wave energy flux in the corona can be explored using the electron density and velocity amplitude of the waves. The velocity amplitude of Alfv\'en waves can be obtained from the non-thermal velocity of the spectral line…

太阳与恒星天体物理 · 物理学 2019-07-03 Girjesh R. Gupta , G. Del Zanna , H. E. Mason

We show that a helical shear flow of a magnetized plasma may serve as an efficient amplifier of Alfven waves. We find that even when the flow is purely ejectional (i.e., when no rotation is present) Alfven waves are amplified through the…

天体物理学 · 物理学 2009-11-07 Andria D. Rogava , Swadesh M. Mahajan , Gianluigi Bodo , Silvano Massaglia

Observations have shown that magnetohydrodynamic waves over a large frequency range are ubiquitous in solar prominences. The waves are probably driven by photospheric motions and may transport energy up to prominences suspended in the…

太阳与恒星天体物理 · 物理学 2016-07-13 Roberto Soler , Jaume Terradas , Ramon Oliver , Jose Luis Ballester

This work is an extension of Kaghashvili [1999] where ion-cyclotron wave dissipation channel for Alfv\'en waves was discussed. While our earlier study dealt with the mode coupling in the commonly discussed sense, here we study changes in…

太阳与恒星天体物理 · 物理学 2014-02-10 Edisher Kh. Kaghashvili

The AlF molecule, currently subject to laser cooling and trapping efforts, has the advantage that it can be efficiently produced in a thermochemical reaction between sublimated aluminum trifluoride and aluminum metal. Here we present a…

A growing body of evidence suggests that the solar wind is powered to a large extent by an Alfv\'en-wave (AW) energy flux. AWs energize the solar wind via two mechanisms: heating and work. We use high-resolution direct numerical simulations…

太阳与恒星天体物理 · 物理学 2021-05-05 Jean C. Perez , Benjamin D. G. Chandran , Kristopher G. Klein , Mihailo M. Martinović

The standard cooling flow model has predicted a large amount of cool gas in the clusters of galaxies. The failure of the Chandra and XXM-Newton telescopes to detect cooling gas (below 1-2 keV) in clusters of galaxies has suggested that some…

天体物理学 · 物理学 2007-10-13 Nasser Mohamed Ahmed

We investigate off-limb active region and quiet Sun corona using spectroscopic data. Active region is clearly visible in several spectral lines formed in the temperature range of 1.1--2.8 MK. We derive electron number density using line…

太阳与恒星天体物理 · 物理学 2017-02-07 G. R. Gupta

Recent studies have shown that galaxies accrete most of their baryons via the cold mode, from streams with temperatures T~10^4-10^5 K. At these temperatures, the streams should radiate primarily in the Lya line and have therefore been…

宇宙学与河外天体物理 · 物理学 2015-05-19 C. -A. Faucher-Giguere , D. Keres , M. Dijkstra , L. Hernquist , M. Zaldarriaga