Probing the Solar Magnetic Field with a Sun-Grazing Comet

Science ◽  
2013 ◽  
Vol 340 (6137) ◽  
pp. 1196-1199 ◽  
Author(s):  
Cooper Downs ◽  
Jon A. Linker ◽  
Zoran Mikić ◽  
Pete Riley ◽  
Carolus J. Schrijver ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Corona ◽  
Solar Magnetic Field ◽  
Extreme Ultraviolet ◽  
Inhomogeneous Magnetic Field ◽  
Multiple Perspectives ◽  
Plasma Properties ◽  
Cometary Tail ◽  
Magnetohydrodynamic Model ◽  
Ultraviolet Observations

On 15 and 16 December 2011, Sun-grazing comet C/2011 W3 (Lovejoy) passed deep within the solar corona, effectively probing a region that has never been visited by spacecraft. Imaged from multiple perspectives, extreme ultraviolet observations of Lovejoy's tail showed substantial changes in direction, intensity, magnitude, and persistence. To understand this unique signature, we combined a state-of-the-art magnetohydrodynamic model of the solar corona and a model for the motion of emitting cometary tail ions in an embedded plasma. The observed tail motions reveal the inhomogeneous magnetic field of the solar corona. We show how these motions constrain field and plasma properties along the trajectory, and how they can be used to meaningfully distinguish between two classes of magnetic field models.

CORRELATION OF CORONAL PLASMA PROPERTIES AND SOLAR MAGNETIC FIELD IN A DECAYING ACTIVE REGION

2016 ◽  
Vol 826 (2) ◽  
pp. 126 ◽  
Author(s):  
Yuan-Kuen Ko ◽  
Peter R. Young ◽  
Karin Muglach ◽  
Harry P. Warren ◽  
Ignacio Ugarte-Urra
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Solar Magnetic Field ◽  
Coronal Plasma ◽  
Plasma Properties

scholarly journals Magnetic field line braiding in the solar atmosphere

2016 ◽  
Vol 12 (S327) ◽  
pp. 77-81
Author(s):  
S. Candelaresi ◽  
D. I. Pontin ◽  
G. Hornig
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Solar Corona ◽  
Field Line ◽  
Solar Atmosphere ◽  
Magnetic Field Line ◽  
Solar Magnetic Field ◽  
Near Surface ◽  
Magnetic Field Topology ◽  
The Magnetic Field

AbstractUsing a magnetic carpet as model for the near surface solar magnetic field we study its effects on the propagation of energy injectected by photospheric footpoint motions. Such a magnetic carpet structure is topologically highly non-trivial and with its magnetic nulls exhibits qualitatively different behavior than simpler magnetic fields. We show that the presence of magnetic fields connecting back to the photosphere inhibits the propagation of energy into higher layers of the solar atmosphere, like the solar corona. By applying certain types of footpoint motions the magnetic field topology is is greatly reduced through magnetic field reconnection which facilitates the propagation of energy and disturbances from the photosphere.

scholarly journals Non-thermal line broadening due to braiding-induced turbulence in solar coronal loops

2020 ◽  
Vol 639 ◽  
pp. A21 ◽  
Author(s):  
D. I. Pontin ◽  
H. Peter ◽  
L. P. Chitta
Keyword(s):  
Magnetic Field ◽  
Extreme Ultraviolet ◽  
Plasma Heating ◽  
Heating Process ◽  
Coronal Loops ◽  
Line Broadening ◽  
Magnetohydrodynamic Model ◽  
Non Gaussian ◽  
Thermal Line ◽  
Solar Coronal

Aims. Emission line profiles from solar coronal loops exhibit properties that are unexplained by current models. We investigate the non-thermal broadening associated with plasma heating in coronal loops that is induced by magnetic field line braiding. Methods. We describe the coronal loop by a 3D magnetohydrodynamic model of the turbulent decay of an initially-braided magnetic field. From this, we synthesised the Fe XII line at 193 Å that forms around 1.5 MK. Results. The key features of current observations of extreme ultraviolet (UV) lines from the corona are reproduced in the synthesised spectra: (i) Typical non-thermal widths range from 15 to 20 km s−1. (ii) The widths are approximately independent of the size of the field of view. (iii) There is a correlation between the line intensity and non-thermal broadening. (iv) Spectra are found to be non-Gaussian, with enhanced power in the wings of the order of 10–20%. Conclusions. Our model provides an explanation that self-consistently connects the heating process to the observed non-thermal line broadening. The non-Gaussian nature of the spectra is a consequence of the non-Gaussian nature of the underlying velocity fluctuations, which is interpreted as a signature of intermittency in the turbulence.

scholarly journals THERMODYNAMICS OF THE SOLAR CORONA AND EVOLUTION OF THE SOLAR MAGNETIC FIELD AS INFERRED FROM THE TOTAL SOLAR ECLIPSE OBSERVATIONS OF 2010 JULY 11

2011 ◽  
Vol 734 (2) ◽  
pp. 120 ◽  
Author(s):  
Shadia Rifai Habbal ◽  
Miloslav Druckmüller ◽  
Huw Morgan ◽  
Adalbert Ding ◽  
Judd Johnson ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Corona ◽  
Solar Eclipse ◽  
Solar Magnetic Field ◽  
Total Solar Eclipse ◽  
Eclipse Observations

Extreme ultraviolet observations of the solar corona: First results from the coronal diagnostic spectrometer on SOHO

1997 ◽  
Vol 20 (12) ◽  
pp. 2239-2248 ◽  
Author(s):  
R.A. Harrison ◽  
A. Fludra ◽  
E.C. Sawyer ◽  
J.L. Culhane ◽  
K. Norman ◽  
...  
Keyword(s):  
Solar Corona ◽  
Extreme Ultraviolet ◽  
First Results ◽  
Ultraviolet Observations ◽  
Coronal Diagnostic Spectrometer

scholarly journals Strong non-radial propagation of energetic electrons in solar corona

2018 ◽  
Vol 614 ◽  
pp. A61 ◽  
Author(s):  
A. Klassen ◽  
N. Dresing ◽  
R. Gómez-Herrero ◽  
B. Heber ◽  
A. Veronig
Keyword(s):  
Magnetic Field ◽  
Solar Corona ◽  
Energetic Particle ◽  
Extreme Ultraviolet ◽  
Energetic Electron ◽  
Solar Energetic Particle ◽  
Source Surface ◽  
Energetic Electrons ◽  
Particle Source ◽  
Jet Trajectory

Analyzing the sequence of solar energetic electron events measured at both STEREO-A (STA) and STEREO-B (STB) spacecraft during 17–21 July 2014, when their orbital separation was 34°, we found evidence of a strong non-radial electron propagation in the solar corona below the solar wind source surface. The impulsive electron events were associated with recurrent flare and jet (hereafter flare/jet) activity at the border of an isolated coronal hole situated close to the solar equator. We have focused our study on the solar energetic particle (SEP) event on 17 July 2014, during which both spacecraft detected a similar impulsive and anisotropic energetic electron event suggesting optimal connection of both spacecraft to the parent particle source, despite the large angular separation between the parent flare and the nominal magnetic footpoints on the source surface of STA and STB of 68° and 90°, respectively. Combining the remote-sensing extreme ultraviolet (EUV) observations, in-situ plasma, magnetic field, and energetic particle data we investigated and discuss here the origin and the propagation trajectory of energetic electrons in the solar corona. We find that the energetic electrons in the energy range of 55–195 keV together with the associated EUV jet were injected from the flare site toward the spacecraft’s magnetic footpoints and propagate along a strongly non-radial and inclined magnetic field below the source surface. From stereoscopic (EUV) observations we estimated the inclination angle of the jet trajectory and the respective magnetic field of 63° ± 11° relative to the radial direction. We show how the flare accelerated electrons reach very distant longitudes in the heliosphere, when the spacecraft are nominally not connected to the particle source. This example illustrates how ballistic backmapping can occasionally fail to characterize the magnetic connectivity during SEP events. This finding also provides an additional mechanism (one among others), which may explain the origin of widespread SEP events.

scholarly journals Magnetically coupled atmosphere, fast sausage MHD waves, and forced magnetic field reconnection during the SOL2014-09-10T17:45 flare

2020 ◽  
Vol 643 ◽  
pp. A140
Author(s):  
H. Mészárosová ◽  
P. Gömöry
Keyword(s):  
Magnetic Field ◽  
Solar Corona ◽  
Solar Atmosphere ◽  
Extreme Ultraviolet ◽  
Free Field ◽  
Mhd Waves ◽  
Field Energy ◽  
Plasma Flows ◽  
The Individual ◽  
The Waves

Aims. We study the physical properties and behaviour of the solar atmosphere during the GOES X1.6 solar flare on 2014 September 10. Methods. The steady plasma flows and the fast sausage MHD waves were analysed with the wavelet separation method. The magnetically coupled atmosphere and the forced magnetic field reconnection were studied with the help of the Vertical-Current Approximation Non-linear Force-Free Field code. Results. We studied a mechanism of MHD wave transfer from the photosphere without dissipation or reflection before reaching the corona and a mechanism of the wave energy distribution over the solar corona. We report a common behaviour of (extreme)ultraviolet steady plasma flows (speed of 15.3 → 10.9 km s−1) and fast sausage MHD waves (Alfvén speed of 13.7 → 10.3 km s−1 and characteristic periods of 1587 → 1607 s), propagating in cylindrical plasma waveguides of the individual atmospheric layers (photosphere → corona) observed by SDO/AIA/HMI and IRIS space instruments. A magnetically coupled solar atmosphere by a magnetic field flux tube above a sunspot umbra and a magnetic field reconnection forced by the waves were analysed. The solar seismology with trapped, leakage, and tunnelled modes of the waves, dissipating especially in the solar corona, is discussed with respect to its possible contribution to the outer atmosphere heating. Conclusions. We demonstrate that a dispersive nature of fast sausage MHD waves, which can easily generate the leaky and other modes propagating outside of their waveguide, and magnetic field flux tubes connecting the individual atmospheric layers can distribute the magnetic field energy across the active region. This mechanism can contribute to the coronal energy balance and to our knowledge on how the coronal heating is maintained.

scholarly journals Magneto-seismology: effect of inhomogeneous magnetic field on transversal coronal loop oscillations

2007 ◽  
Vol 3 (S247) ◽  
pp. 123-132
Author(s):  
G. Verth
Keyword(s):  
Magnetic Field ◽  
Fine Structure ◽  
Plasma Density ◽  
Coronal Loop ◽  
Extreme Ultraviolet ◽  
Wave Theory ◽  
Inhomogeneous Magnetic Field ◽  
Solar Dynamics Observatory ◽  
Flare Loop ◽  
Solar Dynamics

AbstractThe extreme-ultraviolet (EUV) imagers onboard the planned Solar Dynamics Observatory (SDO) and Solar Orbiter (SO) will offer us the best chance yet of using observations of post-flare loop oscillations to probe the fine structure of the corona. Recently developed magnetohydrodynamic (MHD) wave theory has shown that the properties of loop oscillations depend on their plasma fine structure. Up to this point, many studies have concentrated solely on the effect of plasma density stratification on coronal loop oscillations. In this paper we develop MHD wave theory which models the effect of an inhomogeneous magnetic field on coronal loop oscillations. The results have the potential to be used in testing the efficacy of photospheric magnetic field extrapolations and have important implications regarding magneto-seismology of the corona.

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