The possibility that coronal heating occurs by means of anomalous Joule heating by electrostatic ion
NASA Technical Reports Server (NTRS)
Classical T Tauri stars are observed to be surrounded by both accretion flows and some kind of wind or jet-like outflow. There are several possible explanations of how and where the outflows arise, including disk winds, X-winds, impulsive (CME-like) ejections, and stellar winds. Recent work by Matt and Pudritz has suggested that if there is a stellar wind with a mass loss rate about 0.1 times the ...
Energy Citations Database
A model is investigated for the decay of flare heated coronal loops in which rapid radiative cooling
It has been shown that the coronal hole, and the associated high-speed stream in the solar wind, are
their thermodynamic properties are determined by the yet-to-be-established mechanism of coronal heating. Our understanding of coronal loops and coronal ...
NASA Website
1610 in quiescence GW Lib after April 2007 outburst Implications and future work #12;Background Some pulsation modes is crucial Irregular heating events from accretion-driven outbursts (none observed before for this fainter source #12;April 2007 outburst in GW Lib On 12th April 2007, GW Lib went into outburst � the first
E-print Network
Various aspects of solar prominences and the solar corona are discussed. The formation of prominences, prominence diagnostics and structure, prominence dissappearance, large scale coronal structure, coronal diagnostics, small scale coronal structure, and non-equilibrium/coronal heating are ...
We focus on the two topics in this program: (1) magnetic properties at the footpoints of the coronal loops, and (2) coronal activities caused by satellite ...
The dissipation of shear Alfven waves in a coronal loop driven externally by an incident wave in the
Jan 18, 2007 ... A number of mechanisms have been proposed to explain coronal heating, The two most commonly proposed mechanisms are wave heating ...
A potential way of distinguishing between different coronal heating mechanisms is by either broadening or Doppler shifts in spectra lines. Parameterizations of coronal heating models in terms of their dynamical signature are developed and it is shown that...
National Technical Information Service (NTIS)
Feb 25, 2008 ... Nonlinear Studies of Coronal Heating by the Resonant Absorption of Alfven Waves. A series of animations showing various quantities from a ...
... in Coronal Heating and Solar Wind Acceleration ... role in heating the solar atmosphere at ... a stochastic process whose integrated effect (resulting from ...
DTIC Science & Technology
Aug 14, 2005 ... Heating Coronal Loops Credit: M. Aschwanden et al. (LMSAL), TRACE, NASA. Explanation: Why is the corona of the Sun so hot? ...
A simplified nonlinear numerical model for the development of incompressible magnetohydrodynamics in
structure of the corona in slowly changing active regions, deriving the frequency of microflares vs evolution. Key words: corona, heating, MHD, coronal morphol� ogy. 1. INTRODUCTION ''How is the solar corona heated to million degrees?'' and ''How is the heating of the corona related to its structuring
We examine the magnetic origins of coronal heating in quiet regions by combining SOHO/EIT Fe XII coronal images and Kitt Peak magnetograms. Spatial filtering of the coronal images shows a network of enhanced structures on the scale of the magnetic network in quiet regions. Superposition of the filtered ...
NASA Astrophysics Data System (ADS)
... Abstract : We investigate a model for the decay of flare heated coronal loops in which rapid radiative cooling at the loop base creates strong ...
The main thrust and significance of our research results are presented. The topics covered include: (1) coronal structure and dynamics; (2) coronal heating; (3) filament formation; and (4) flare energy release.
May 29, 2008 ... Warm Coronal Loops Offer Clue to Mysteriously Hot Solar Atmosphere ... with the right mix of particle acceleration and direct heating, ...
Using model calculations based on a self-consistent treatment of the coronal energy balance, we show
Scaling laws are very useful for studying the heating and equilibrium properties of coronal ... scaling laws, it is possible to determine if the heating ...
Recent observational data cast serious doubt on the widely held view that the sun's corona is heated
Recent observational data cast serious doubt on the widely held view that the sun:s corona is heated
Recent observational data cast serious doubt on the widely held view that the Sun's corona is heated
... to result in the heating of the solar corona ... energy is transformed into kinetic energy, and the ... Concentrated vorticity structures are seen to play almost ...
An observational search has been made for intensity fluctuations associated with the wave motions that are thought to heat the corona. Brightness changes in the coronal green line (Fe XIV lambda 5303) and the coronal continuum were measured with the Unive...
The Sun's atmosphere or corona is millions of degrees hotter than its 5,000 K surface or photosphere. This heating enigma is typically addressed by invoking the deposition at coronal heights of non-thermal energy generated by the interplay between convection and magnetic field near the photosphere. However, it remains unclear how and where ...
Jan 22, 2011 ... dc.title, Coronal heating, weak MHD turbulence, and scaling laws, en_US. dc.type , Article, en_US. Appears in Collections: JPL TRS 1992+ ...
Jan 22, 2011 ... Title: Coronal heating, weak MHD turbulence, and scaling laws. Authors: Rappazzo , A. F.. Velli, M. Einaudi, G. Dahlburg, R. B. ...
A short review is given about the self-consistent MHD model of solar coronal heating recently proposed by Bigot et al.(2008) in which the dynamical effect of the background magnetic field along a coronal structure is taken into account through exact results from Alfven wave turbulence. The main properties of the model are given as well ...
... Title : Environmental Conditions Responsible for Solar Activity. Descriptive ... Solar activity, Coronal heating, Flares, Magnetic fields. Descriptors ...
Reported observations in H?, Ca II H, and K or other chromospheric lines of coronal rain trace back to the days of the Skylab mission. Corresponding to cool and dense plasma, coronal rain is often observed falling down along coronal loops in active regions. A physical explanation for this spectacular phenomenon has been put forward ...
Reported observations in H{alpha}, Ca II H, and K or other chromospheric lines of coronal rain trace back to the days of the Skylab mission. Corresponding to cool and dense plasma, coronal rain is often observed falling down along coronal loops in active regions. A physical explanation for this spectacular phenomenon has been put ...
I propose a new paradigm for solar coronal heating viewed as a self-regulating process keeping the plasma marginally collisionless. The mechanism is based on the coupling between two effects. First, coronal density controls the plasma collisionality and hence the transition between the slow collisional Sweet-Parker and the fast ...
PubMed
Numerical calculations governing the efficiency of coronal loop heating by the resonant absorption of shear Alfven waves are reported. The loop structure is modeled by a class of axisymmetric force-free equilibria of a long straight cylinder, approximating a large aspect ratio loop. For a range of parameters characterizing the evolution of solar ...
The electron heating of the solar coronal plasma has remained as one of the most important problems in solar physics. An explanation of the electron heating rests on the identification of the energy source and appropriate physical mechanisms via which the energy can be channelled to the electrons. Our objective here is to present an ...
Sep 28, 2000 ... Recorded in extreme ultraviolet light, this and other TRACE images indicate that most of the heating occurs low in the corona, near the ...
Numerous mechanisms of coronal heating have been pro- posed (e.g. wave heating, nanoflares, ... chromospheric temperatures at roughly 7000K. The internal ...
conduction (35 times smaller than electron heat conduction). No collisionless heat conduction .... multigroup radiation diffusion) for the Convection Zone ...
It is shown that the physical properties of the chromosphere play a crucial role in determining the thermal stability of coronal loops. A simple rigorous analysis of thermal stability is given which is valid for heating functions independent of space. Unless a negative feedback mechanism exists whereby a coronal temperature ...
Coronal seismology, a new field of solar physics that emerged over the last 5 years, provides unique information on basic physical properties of the solar corona. The inhomogeneous coronal plasma supports a variety of magnetohydrodynamics (MHD) wave modes, which manifest themselves as standing waves (MHD oscillations) and propagating waves. Here, we ...
Loss of hydrostatic equilibrium of a coronal magnetic loop as a result of an increase of the magnetic field under the loop and as a result of a flare induced heating of plasma inside the loop is considered. The expanding magnetic loops act as a piston in ...
Characteristics of solar flares, such as their impulsive nature, time scale, heating, high-energy particle spectrum, and ..gamma..-ray oscillations, as well as recent X-ray photographs of coronal brightening, are explained by the nonlinear coalescence instability of current loops.
Characteristics of solar flares such as their impulsive nature, time scale, heating, high energy particle spectrum, (BETA)-ray oscillations as well as recent X-ray photographs of coronal brightening are explained by the nonlinear coalescence instability of current loops.
We calculate the XUV line and broad-band emission from a model active-region loop. The spectrum is found to be sensitive to both the coronal heating rate and to the loop geometry. (Author)
Solar and stellar X-ray emission are the observed waste products of the interplay between magnetic fields and the motion of stellar plasma. Theoretical understanding of the process of coronal heating is of utmost importance, since the high temperature is ...
We present the results of a multi-wavelength study of episodic plasma injection into the corona of active region (AR) 10942. We exploit long-exposure images of the Hinode and Transition Region and Coronal Explorer spacecraft to study the properties of faint, episodic, "blobs" of plasma that are propelled upward along coronal loops that are rooted in the AR ...
We present the results of a multi-wavelength study of episodic plasma injection into the corona of active region (AR) 10942. We exploit long-exposure images of the Hinode and Transition Region and Coronal Explorer spacecraft to study the properties of faint, episodic, 'blobs' of plasma that are propelled upward along coronal loops that ...
The motivation of this work has been to provide observational constraints on coronal heating models by testing their predictions for the heating rate as a function of several physical parameters. In Mandrini et al. (1999), we have investigated how the magnetic field strength, , of coronal flux tubes depends on the ...
Solar prominences are cool 10(4) kelvin plasma clouds supported in the surrounding 10(6) kelvin coronal plasma by as-yet-undetermined mechanisms. Observations from Hinode show fine-scale threadlike structures oscillating in the plane of the sky with periods of several minutes. We suggest that these represent Alfv�n waves propagating on coronal magnetic ...
The recent discovery of Type II spicules has generated considerable excitement. It has even been suggested that these ejections can account for a majority of the hot plasma observed in the corona, thus obviating the need for "coronal� heating. If this is the case, however, then there should be observational consequences. We have begun to examine some of ...
We quantify the scaling of magnetic energy density in the inertial range of solar-wind turbulence seen in situ at 1 AU with respect to solar activity. At solar maximum, when the coronal magnetic field is dynamic and topologically complex, we find self-similar scaling in the solar wind, whereas at solar minimum, when the coronal fields are more ordered, we ...
The goal of this review is to outline some new ideas in the physics of coronal magnetic loops, the fundamental structural elements of the atmospheres of the Sun and flaring stars, which are involved in phenomena such as stellar coronal heating, flare energy release, charged particle acceleration, and the modulation of optical, radio, ...
Sep 20, 1996 ... Scaling laws, i.e. simple relations between fundamental properties of quasi- steady coronal loops (temperature, length, pressure and heating ...
Jun 16, 2011 ... Thermodynamic Structure of Collision-dominated Expanding Plasma: Heating of interplanetary Coronal Mass Ejections. J. Geophys. ...
Several studies in the mid 1980's, supported by the SEC Theory Program, at the University of ... This is a case in which the SEC Theory Program has produced ...
Solar plasma that exists at around 10^5 K, which has traditionally been referred to as the solar transition region, is probably in a dynamic and fibril state with a small filling factor. Its origin is as yet unknown, but we suggest that it may be produced primarily by one of five different physical mechanisms, namely: the heating of cool spicular material; the containment of ...
This article presents text, images, and animations of a solar flare and coronal mass ejection that occurred in August 1999. Links to related topics and articles are inlcuded.
NSDL National Science Digital Library
Jan 6, 1998 ... He suggested to shift the priorities to elemental abundances and coronal heating processes (e.g. MHD waves). He also suggested to test and ...
Cargill. The Experimental. Signatures of Coronal Heating Mechanism. Goldman and Newman. Space-Timne. Structure of Langmuir. Turbulence ...
... A and B to the system's total X-ray ... 11.5% respectively), consideration of mass loss measurements for ... indicating that the coronal heating process in ...
... to Solar Magnetic Cloud/Coronal Mass Ejection (SMC/CME) events, and 6) the effects of Joule heating on the thermodynamics of the Antarctic F-region. ...
... Helium: Direct Evidence for Local Heating by Alfven-Cyclotron Dissipation( abstract) ... Tongjiang Wang (Oscillations and Waves in Solar Coronal Loops); ...
Solar Probe Plus will repeatedly sample the near-Sun environment, revolutionizing our knowledge and understanding of coronal heating and of the origin and evolution of the solar...
Science.gov Websites
... inhomogeneous plasmas, the acceleration of high speed wind streams in solar and stellar coronal holes, and plasma heating in closed magnetic structures. ...
The energy requirements of noise stroms are probably below those of coronal heating ... Interaction between the "moving magnetic features" or MMFs of mixed ...
Jan 7, 2011 ... Hotspots in Fountains on the Sun's Surface Help Explain Coronal Heating ... Tracking the movement and temperature of spicules relies on ...
Observation with SOT. Photosphere-corona connections. Coronal heating. Flare/CME physics. Reconnection physics, Site of large non-thermal line broadening, & ...
Dec 6, 2007 ... Alfven waves were a long-time suspect in the coronal heating mystery ... An Alfven wave is a vibration of a magnetic field line that carries ...
19 hours ago ... The letter represents a factor of 10 change in the X-ray intensity as ... heating the coronal gas by electrical currents, and throwing part of the ...
The pressure gradient induced in a coronal loop by proton beam momentum deposition is calculated and
Jan 6, 2011... in the spicules, the scientists believe that if even some of that super hot plasma stays aloft it would make a contribution to coronal heating. ...
Introducing Alfven Waves Turbulence. " Hinode observations suggest energy input is sufficient to drive the solar wind acceleration and heating (de Pontiue ...
Recent observational data cast serious doubt on the widely held view that the Sun's corona is heated by traveling waves (acoustic or magnetohydrodynamic). It is proposed that the energy responsible for heating the corona is derived from the free energy of...
Recent observational data cast serious doubt on the widely held view that the sun's corona is heated by traveling waves (acoustic or magnetohydrodynamic). It is here proposed that the energy responsible for heating the corona is derived from the free ener...
Several recent observational results suggest that coronal mass ejection (CME) plasma is heated even after leaving the flare site. The source of the heating is probably the magnetic field of the erupting flux rope, but the mechanisms that convert magnetic to thermal energy during these events are not well understood. By performing a ...
We use coordinated observations from the Solar Dynamics Observatory (SDO), Hinode and the Swedish Solar Telescope (SST) to show how plasma is heated to coronal temperatures from its source in the chromosphere. Our observations reveal a ubiquitous mass supply for the solar corona in which chromospheric plasma is accelerated upward into the corona with much ...
The Parker or field line tangling model of coronal heating is investigated through long-time high-resolution simulations of the dynamics of a coronal loop in cartesian geometry within the framework of reduced magnetohydrodynamics (RMHD). Slow photospheric motions induce a Poynting flux which saturates by driving an anisotropic ...
It has been established that small scale heating events, known as nanoflares, are important for solar coronal heating if the power-law distribution of their energies has a slope ? steeper than -2 ( ?<-2). Forward modeling of impulsively heated coronal loops with a set of prescribed power-law ...
A simple method is presented for diagnosing the electron temperature and density of a rapidly heated, coronal-type plasma from observable, non-equilibrium enhancements of X-ray line emission. This method, it is argued, is applicable to the study of solar ...
We discuss the following subjects: 1) the discovery of chromospheric jets by Hinode/SOT and comparison with the reconnection model, 2) the discovery of propagating Alfv�n waves associated with a chromospheric jet and the generation of the wave via magnetic reconnection, 3) the energy estimation of the propagating Alfv�n wave and its implications for coronal ...
: Prof. J, Heyvaerts. Title: `Statistical model of quiet Sun coronal heating' . The basic idea Geophysical Union, American Geophysical Union, Cospar - LOC member SOHO 20 - LOC member of 4 summer school, 679, 311-314 (2003) 14- Statistical Model of quiet Sun coronal heating, O. Podladchikova, Orl�ans
The condensations composing coronal rain, falling down along loop-like structures observed in cool chromospheric lines such as H? and Ca II H, have long been a spectacular phenomenon of the solar corona. However, considered a peculiar sporadic phenomenon, it has not received much attention. This picture is rapidly changing due to recent high-resolution observations with ...
We present simulated coronal emission pictures of some case-study solar active regions, including NOAA-designated regions 8210 and 8038. The simulated emissions are calculated from a 3-d temperature, density, and magnetic field model of the corona based on first principles. The method involves a static energy balance along individual coronal loops, with ...
We have modelled the solar wind response to a time-dependent energy input in the corona. The model, which extends from the upper chromosphere to 1 AU, solves the time-dependent transport equations based on the gyrotropic approximation to the 16-moment set of transport equations, which allow for temperature anisotropies. Protons are heated perpendicularly to the magnetic field, ...
Ronald L. Moore. 27 June 2003. Socialization : 10:15 a.m.. Presentation : 10:30 a.m.. We investigate the heating of the quiet corona by measuring the ...
A study was made on the process of plasma heating up to ignition in a tokamak during fast neutral atom injection considering impurity influence. A series of effects (nonstationarity, impurity charge exchange on hydrogen atoms) resulting in the increase of...
Solar wind data obtained with ion mass-energy-spectrometer on the Prognoz 7 satellite are analyzed to study the alpha-particle and proton features in different types of solar wind streams. In the streams from coronal holes the abundance of helium relative to proton slightly increases with increasing solar wind flux and proton density while in the streams from ...
Coronal hole regions are well known sources of high-speed solar wind, however to account for the observed properties of the solar wind a source of energy must be included in addition to heat conduction. Alfven waves were suggested as the possible source of heating that accelerates the solar wind. We investigate the ...
For each of six old bipolar active regions, we present and interpret Yohkoh/SXT and SOHO/MDI observations of the development, over several days, of enhanced coronal heating in and around the old bipole in response to new magnetic flux emergence within the old bipole. The observations show: 1. In each active region, new flux emerges in the equatorward side ...
Past attempts to explain the large solar wind velocities in high speed streams by theoretical models of the expansion have invoked either extended nonthermal heating of the corona, heat flux inhibition, or direct addition of momentum to the expanding coronal plasma. Several workers have shown that inhibiting the ...
DOE Information Bridge
One puzzling observed property of coronal loops is that they are of roughly constant thickness along their length. Various studies have found no consistent pattern of width variation along the length of loops observed by TRACE and SOHO. This is at odds with expectations of magnetic flux tube expansion properties, which suggests that loops are widest at their tops, and ...
The Sun's outer atmosphere, or corona, is heated to millions of degrees, considerably hotter than its surface or photosphere. Explanations for this enigma typically invoke the deposition in the corona of nonthermal energy generated by magnetoconvection. However, the coronal heating mechanism remains unknown. We used observations from ...
We examine the possibility that the corona is heated by a train of weak switch-on shocks which are formed in the chromosphere from a train of Alfven waves, and which subsequently enter the corona from below. New results for the shock train propagation and dissipation and the resultant coronal heating are derived. It is shown that most ...
compact binaries. Kronos will obtain broad energy range spectroscopic data with ... Doppler tomography and eclipse mapping techniques characterize and map .... by a distribution of relativistic electrons (and possibly positrons) with ...
Kronos is a multiwavelength observatory proposed as a NASA Medium Explorer. Kronos is designed to make use of the natural variability of accreting sources to create microarcsecond-resolution maps of the environments of supermassive black holes in active g...
Several recent observational results suggest that coronal mass ejection (CME) plasma is heated even after leaving the flare site. The source of the heating is probably the magnetic field, but the mechanisms that convert magnetic to thermal energy during these events are not well understood. We perform a time-dependent ionization ...
We study wave propagation in the low-beta coronal plasma using a collisionless multi-fluid model. Neglecting the electron inertia, this model allows us to take into account ion-cyclotron wave effects that are absent in the magnetohydrodynamics model. To accomplish this, we perform a Fourier plane-wave perturbation analysis. Solving numerically the dispersion relations obtained ...
The Hinode EUV Imaging Spectrometer (EIS) has revealed the presence of high-velocity upflow components of nearly coronal sound speed near the footpoints of active region loops in a quiescent active region. The upflow is detected as subsonic line shifts with enhanced line broadenings when the emission line fitting by a Gaussian function is applied to the line-profile analysis ...
The Sun's corona is millions of degrees hotter than its 5000 K photosphere. This heating enigma is typically addressed by invoking the deposition at coronal heights of nonthermal energy generated by the interplay between convection and magnetic field near the photosphere. However, it remains unclear how and where coronal ...
We present the observations of the contraction of the EUV coronal loops overlying the flaring region during the pre-heating as well as the early impulsive phase of a C8.9 flare. During the relatively long, 6 minutes, pre-heating phase, the flare emission is dominated by a thermal looptop source with the temperature of 20 - 30 MK. After ...
Impulsive nanoflares are expected to transiently heat the plasma confined in coronal loops to temperatures of the order of 10 MK. Such hot plasma is hardly detected in quiet and active regions, outside flares. During rapid and short heat pulses in rarefied loops, the plasma can be highly out of equilibrium in ionization. Here we ...
The heating of the plasma in the solar atmosphere is discussed within both frameworks of fluid and kinetic drift wave theory. We show that the basic ingredient necessary for the heating is the presence of density gradients in the direction perpendicular to the magnetic field vector. Such density gradients are a source of free energy for the excitation of ...
By examining the magnetic structure at sites in the bright coronal interiors of active regions that are not flaring but exhibit persistent strong coronal heating, we establish some new characteristics of the magnetic origins of this heating. We have examined the magnetic structure of these sites in five active ...
We study how the solar atmosphere and wind respond to sudden and large increases in the coronal energy input, with the aim of better understanding the impact of fast coronal mass ejections on the lower solar atmosphere. We apply a gyrotropic multifluid model extending from the chromosphere to 1 AU and that accounts for radiative losses in the transition ...
Various papers on solar and stellar coronal structure and dynamics are presented. The general topics addressed include: stellar coronae; winds, holes, and bright points; waves, oscillations, and heating; prominence interface; structures; solar-cycle variations; observations and models of magnetic fields; mass ejections, transients, and flares.
I will discuss recent results using Hinode/SOT-EIS-XRT, SOHO/SUMER, CRISP (at the Swedish Solar Telescope) and TRACE that provide a direct connection between coronal dynamics and those of the lower atmosphere. We use chromospheric measurements (H-alpha and Ca II 8542 spectral imaging, and Ca II H images), as well as UV spectra (EIS and SUMER), and EUV/X-ray images (XRT and ...
MHD turbulence has long been proposed as a mechanism for the heating of coronal loops in the framework of the Parker scenario for coronal heating. So far most of the studies have focused on its dynamical properties without considering its thermodynamical and radiative features, because of the very demanding ...
We have derived the viscous MHD equilibrium and perturbed equations for a current carrying cylindrical plasma in a previous paper. We have considered compressible plasmas and, the viscosity is introduced in the equation of motion leading to a linearized third order perturbed equation for the fluid displacement. Including the flowing equilibrium and viscosity, we have shown the appearance of non ...
We have recently presented a mechanism for preferential acceleration and heating of coronal hole minor ions [1, 2]. The energization is due to the effect of multiple cyclotron resonances in the presence of sunward and anti-sunward dispersive ion cyclotron waves, providing a second-order Fermi interaction. The mechanism is preferential because ...
Solar wind data obtained with ion mass-energy-spectrometer on the Prognoz 7 satellite are analyzed to study the ?-particle and proton features in different types of solar wind streams. In the streams from coronal holes the abundance of helium relative to proton slightly increases with increasing solar wind flux and proton density while in the streams from ...
The presence of chromospheric material evaporating in response to localized heating to coronal temperatures is inferred from Solar Maximum Mission observations of systematic plasma upflows during the rise of the soft X-ray emission in solar flares. This period corresponds also to the interval during which energy is deposited in the chromosphere, as ...
Magnetic reconnection of solar coronal loops is the main process that causes solar flares and possibly coronal heating. In the standard model, magnetic field lines break and reconnect instantaneously at places where the field mapping is discontinuous. However, another mode may operate where the magnetic field mapping is continuous but ...
Spectroscopic observations of V1819 Cyg, V827 Her, and V2214 Oph, obtained at 1-2.5 microns using a 32-channel InSb array detector at the Cassegrain focus of the 2.7-m telescope at McDonald Observatory during 1986-1989, are reported. The data are presented in extensive tables and graphs and characterized in detail, with a focus on the nature of the coronal emission. The ratios ...
The determination of the fine thermal structure of the solar corona is fundamental to constraining the coronal heating mechanisms. The Hinode X-ray Telescope collected images of the solar corona in different passbands, thus providing temperature diagnostics through energy ratios. By combining different filters to optimize the signal-to-noise ratio, we ...
A recently developed simulation model is used to investigate the effects of varying the coronal and electron heating conditions on the dynamic spectra of coronal type III bursts (70-370 MHz) observed at Earth. The flux of 2f p emission is significantly higher than that of f p emission, which is unlikely to be observable except ...
It is often assumed that all heavy ions, including helium, must be much hotter than the protons in order to escape the solar gravitational field and avoid large increases in abundance in the corona. However, in a recent study of iron in the slow solar wind, we have found that "cold" (i.e. with a temperature equal to the proton temperature) iron ions may in some cases escape from the corona simply ...
The cooling of impulsively heated coronal loops is examined with emphasis on the phase when optically thin radiation is dominant over conduction. It is shown that this regime cannot be described as purely 'radiative cooling' because an enthalpy flux to the transition region plays an important and, on occasions, a dominant role. The ...
Strongly damped Doppler shift oscillations are observed frequently associated with flarelike events in hot coronal loops. In this paper, a review of the observed properties and the theoretical modeling is presented. Statistical measurements of physical parameters (period, decay time, and amplitude) have been obtained based on a large number of events observed by SOHO/SUMER and ...
The heating of the solar corona and therefore the generation of the solar wind, remain an active area of solar and heliophysics research. Several decades of in situ solar wind plasma observations have revealed a rich bimodal solar wind structure, well correlated with coronal magnetic field activity. Therefore, the reconnection processes associated with the ...
In the context of coronal heating, among the zoo of magnetohydrodynamic (MHD) waves that exist in the solar atmosphere, Alfv�n waves receive special attention. Indeed, these waves constitute an attractive heating agent due to their ability to carry over the many different layers of the solar atmosphere sufficient energy to ...
I have studied the helium abundance in polar coronal holes and the fast solar wind using a time-dependent numerical model for the hydrogen-helium solar wind that spans the mid-to-upper chromosphere, transition region, corona, and solar wind. The model calculates the particle density, flow velocity, parallel and perpendicular temperature, and heat flux for ...
We present a series of numerical simulations aimed at understanding the nature and origin of turbulence in coronal loops in the framework of the Parker model for coronal heating. A coronal loop is studied via reduced magnetohydrodynamic (MHD) simulations in Cartesian geometry. A uniform and strong magnetic field ...
This paper summarizes the latest results on the research of solar wind helium ions observed on broad the Prognoz 7 satellite. On the basis of solar wind parameter distributions on the 'density-velocity plane' we selected five different types of the solar wind streams which may be connected with the well known solar corona structure and phenomena: (1) the he1iospheric current sheet, (2) streams ...
Using a 16 moment solar wind model extending from the chromosphere to 1 AU, we study how the solar wind is affected by direct deposition of energy in the transition region, in both radially expanding geometries and rapidly expanding coronal holes. Energy is required in the transition region to lift the plasma up to the corona, where additional coronal ...
Transition Region and Coronal Explorer ... Detector: 1024 x 1024 Lumigen coated, front illuminated, three-phase CCD ... reconnection, wave propagation and plasma heating - arise throughout space physics and astrophysics. ...
Magnetohydrodynamic turbulence has been proposed as a mechanism for the heating of coronal active regions, and has therefore been actively investigated in recent years. According to this scenario, a turbulent regime is driven by footpoint motions. The energy being pumped this way into active region loops, is efficiently transferred to small scales due to a ...
This site describes unanswered questions about the sun. These include the coronal heating process, the nature of solar flares, the origin of the sunspot cycle, and missing neutrinos. In each case the problem is stated along with what is known to date. The text includes links to further information.
D. A. Falconer,1,2 R. L. Moore,1 J. G. Porter,1 and D. H. Hathaway1 ..... In Table 3, the area-average radiation fluxes of the bright and dim halves ...
The solar wind electron heat flux is carried primarily by suprathermal ''halo'' electrons beamed antisunward along the interplanetary magnetic field (IMF), indicating magnetic connection to the Sun only in one direction. However, electron observations at ...
Publication Abstracts. Brandt 1967. Brandt, J.C., 1967: Radar observations and the extent of coronal heating. Astron. J. , 149, 447-448, doi:10.1086/149271. ...
A model was develped for the mass, energy, and magnetic field transport into the corona. The focus is on the flow below the photosphere which allows the energy to pass into, and be dissipated within, the solar atmosphere. The high flow velocities observed...
Emission lines formed in the transition region (TR) of the Sun have long been known to show pervasive redshifts. Despite a variety of proposed explanations, these TR downflows (and the slight upflows in the low corona) remain poorly understood. We present results from comprehensive three-dimensional MHD models that span the upper convection zone up to the corona, 15 Mm above the photosphere. The ...
Because coronal plasma is dominated by the photospheric-based magnetic field, the corona is highly structured, the filling factor being no more than .01. Measurement of the magnetic field in the fine structure is fundamental to understanding the heating m...
Using data from the Extreme-ultraviolet Imaging Spectrometer aboard Hinode, we have studied the coronal plasma in the core of two active regions. Concentrating on the area between opposite polarity moss, we found emission measure distributions having an a...
Moore, R. L, Falconer, D., Porter, J. G., Hathaway, D., Yamauchi, Y., and Rabin, D. M. 2005, Coronal Heating, Spicules, and Solar-B, Astron. Soc. ...
