scholarly journals On the Possibility of Local Magnetic Field Intensification in Evaporating Chromospheric Solar Flare Plasma

1989 ◽  
Vol 104 (2) ◽  
pp. 341-344
Author(s):  
V. N. Dermendjiev ◽  
G. T. Buyukliev ◽  
I. Ph. Panayotova
Keyword(s):  
Magnetic Field ◽  
Solar Flare ◽  
Solar Flares ◽  
Local Magnetic Field ◽  
Plume Structure ◽  
The Subject ◽  
Convective Plume ◽  
Flare Plasma ◽  
Initial Magnetic Field ◽  
Moving Vortex

The investigations of plasma motions at the initial phases of solar flares (Antonucci and Dennis, 1983; Doschek, 1983; Watanabe, 1987) suggest evaporation from the chromospheric flaring area. According to de Jager (1983) when seen at the limb the evaporated plasma will look like a “convective plume” and it can be seen separated from heated footpoint areas.The subject of this work is the study of the possibility of forming hydrodynamic structures o-f thermal and starting plume's kind at the time of evaporation of the upper chromosphere in a flaring area. Also the possibility of increasing an initial magnetic field by a periodically moving vortex in a plume structure is investigated.

Solar flare forecasting model using 3D magnetic field data

2020 ◽  
Author(s):  
Xin Huang
Keyword(s):  
Magnetic Field ◽  
Deep Learning ◽  
Solar Flare ◽  
Solar Flares ◽  
Field Data ◽  
Active Regions ◽  
Forecasting Model ◽  
Magnetic Field Data ◽  
The Magnetic Field

<p>Solar flares originate from the release of the energy stored in the magnetic field of solar active regions. Generally, the photospheric magnetograms of active regions are used as the input of the solar flare forecasting model. However, solar flares are considered to occur in the low corona. Therefore, the role of 3D magnetic field of active regions in the solar flare forecast should be explored. We extrapolate the 3D magnetic field using the potential model for all the active regions during 2010 to 2017, and then the deep learning method is applied to extract the precursors of solar flares in the 3D magnetic field data. We find that the 3D magnetic field of active regions is helpful to build a deep learning based forecasting model.</p>

scholarly journals Global response of Magnetic field and Ionosonde observations to intense solar flares on 6 and 10 September 2017

2018 ◽  
Vol 62 ◽  
pp. 01007
Author(s):  
Akiko Fujimoto ◽  
Akimasa Yoshikawa ◽  
Akihiro Ikeda
Keyword(s):  
Magnetic Field ◽  
Solar Flare ◽  
Radio Wave ◽  
Solar Flares ◽  
Ionospheric Disturbance ◽  
Sudden Change ◽  
Magnetic Data ◽  
Sudden Increase ◽  
X Ray ◽  
Night Side

Intense X-ray fluxes during solar flares are known to cause enhanced ionization in the Earth’s ionospheric D, E and F region. This sudden change of ionospheric electron density profile is serious problem to radio wave communication and navigation system. The ground magnetograms often record the sudden change in the sunlit hemisphere during the enhanced X-ray flux, due to the sudden increase in the global ionospheric current system caused by the flare-induced enhanced ionospheric conductivity. These geomagnetic field disturbances are known as ‘‘solar flare effects’’ (SFEs) or geomagnetic crochets [Campbell, 2003]. The typical SFE is increase variation on the equatorial magnetic data. On Ionosonde observation during solar flare event, the High-Frequency (HF) radio wave blackout is often detected in ionogram due to the sudden disturbance in ionosphere. Two intense X-class solar flares occurred on 6 and 10 September 2017. We investigated the magnetic field and Ionosonde responses to the intense solar flare events. Dayside magnetic field variations sudden increased due to the ionospheric disturbance resulting from solar flare. There is no response in night side magnetometer data. The magnitude of SFE (magnetic field) is independent of solar flare x-ray magnitude. We found HF radio wave blackout in ionogram at dayside Ionosonde stations. The duration of blackout is dependent of latitude and local time of Ionosonde stations. There is the different feature of ionogram at night side.

scholarly journals Magnetic fields in limb solar flares on heights 2–14 Mm

2020 ◽  
pp. 6-14
Author(s):  
V. Lozitsky ◽  
I. Yakovkin ◽  
E. Kravchenko
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Solar Flares ◽  
Zeeman Splitting ◽  
Local Magnetic Field ◽  
Echelle Spectrograph ◽  
Superstrong Magnetic Field ◽  
National University ◽  
Field Lines ◽  
The Magnetic Field

We present the results of observations of two powerful limb solar flares which occured on 17 July 1981 and 14 July 2005. Spectral observations of these flares were carried out with the Echelle spectrograph of the Horizontal Solar Telescope of the Astronomical Observatory of Taras Shevchenko National University of Kyiv. In order to measure the magnetic fields in these flares, I ± V profiles of К СаІІ, HeI 4471.5 and Нα lines were studied. It was found that effective (averaged) magnetic field Вeff in the flares reached 1100–3000 G on heights 2–14 Mm. However, the spectral evidences to yet stronger fields of ~ 104 G range were found. In particular, the weak spectral evidences of large Zeeman splitting were found in first flare by HeI 4471.5 line; this evidences corresponds to superstrong magnetic field of 15.5 kG. In the second flare, Нα line has non-parallelism of bisectors of I ± V profiles which can reflect existence of 1550–3000 G fields in the flare. However, in frame of simple two-component model these observed values can correspond to true local (amplitude) magnetic fields Вmax in range 4.65–18 kG. Apparently, such superstrong magnetic fields arise in structures of a force-free type, with strong twisting of the field lines. It is precisely such field values that are necessary in solar flares for energy reasons. Indeed, solar flares emit energy in the range of 1027-1032 erg in a volume of the order of 1027 cm3. Elementary calculations show that in order to provide such energy in such a volume, the magnetic field strength should be at least 103 G. In addition, if we take into account that solar magnetic fields have the sub-telescopic (spatially unresolved) structure, then the local magnetic field intensities in the flares at the coronal level can be expected even higher.

Characteristic of Solar Wind Parameters and Geomagnetic Indices during Solar Flares

2018 ◽  
Vol 13 (S340) ◽  
pp. 257-258
Author(s):  
Roshan K. Mishra ◽  
Binod Adhikari ◽  
Drabindra Pandit ◽  
Narayan P. Chapagain
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Solar Flare ◽  
Solar Flares ◽  
High Speed ◽  
Solar Wind Velocity ◽  
Geomagnetic Indices ◽  
Solar Winds ◽  
Solar Wind Parameters

AbstractActive sun is characterized by compelling short-lived flash of solar eruption like solar flare, coronal mass ejections (CMEs), high-speed solar winds and solar energetic particles along with colossal release of energy and mass. This paper proposes a new method to evaluate solar wind parameters and geomagnetic indices based on wavelet analysis during the solar flares. The crucial role of IMF-Bz (interplanetary magnetic field) is examined for the two solar flares events. The key result obtained from our study is substantial dependence of solar flare intensity on IMF-Bz together with solar wind velocity. We also observed the duration of solar flares and their effect on ionospheric and ground based parameters.

scholarly journals Solar Flare Prediction and Magnetic Field Evolution in Solar Active Region

2002 ◽  
Vol 12 ◽  
pp. 396-397
Author(s):  
H.N. Wang ◽  
G.Q. Zhang ◽  
C.L. Zhu ◽  
J.L. Sun
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Solar Flare ◽  
Solar Flares ◽  
Astronomical Observatory ◽  
Solar Active Region ◽  
Field Evolution

AbstractThe authors propose a number of empirical criteria for prediction of solar flares based on many years of observations at Huairou Solar Observing Station of Beijing Astronomical Observatory.

scholarly journals Magnetic Field Observation with the Solar Flare Telescope

1993 ◽  
Vol 141 ◽  
pp. 166-169 ◽  
Author(s):  
K. Ichimoto ◽  
T. Sakurai ◽  
Y. Nishino ◽  
K. Shinoda ◽  
M. Noguchi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Solar Flare ◽  
Energy Release ◽  
Solar Flares ◽  
Field Observation ◽  
Velocity Fields

AbstractThe Solar Flare Telescope was constructed at Mitaka in 1989. This instrument comprises four telescopes which respectively observe (a) Hα images, (b) continuum images, (c) vector magnetic fields, and (d) velocity fields in the photosphere. The instrument aims at the study of energy build-up and energy release in solar flares, in cooperation with the Solar-A satellite. The whole system has been in regular operation since 1992 July. The methods of measuring the magnetic and velocity fields are described.

scholarly journals The Transient Highly Excited Solar Flare Plasma

1972 ◽  
Vol 14 ◽  
pp. 827-842 ◽  
Author(s):  
L. D. De Feiter
Keyword(s):  
Solar Flare ◽  
Radio Emission ◽  
Special Reference ◽  
Solar Flares ◽  
Energetic Particles ◽  
X Rays ◽  
Microwave Region ◽  
X Ray ◽  
Flare Plasma ◽  
Radiation Processes

AbstractRecent observations of the energetic particles produced in solar flares indicate that the production of electrons, with energies up to about 100 keV, is a fairly common feature of small flares. In those flares the acceleration of protons and other nuclei does not extend beyond about 1 MeV.The X-ray emission often exhibits two distinct components of which the first one is produced by non-thermal, the second by thermal electrons through bremsstrahlung collisions with the ambient ions. Along with these X rays, radio emission, in the microwave region, is observed. This radio emission is usually interpreted as due to gyrosynchrotron radiation from the same electrons.In this review a discussion is presented of the processes occurring in solar flares with special reference to the acceleration and radiation processes.

Characterization of turbulent magnetic reconnection in solar flares with microwave imaging spectroscopy

2020 ◽  
Author(s):  
Gregory Fleishman ◽  
Dale Gary ◽  
Bin Chen ◽  
Sijie Yu ◽  
Natsuha Kuroda ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Particle Acceleration ◽  
Solar Flare ◽  
Magnetic Reconnection ◽  
Solar Flares ◽  
Magnetic Energy ◽  
Imaging Spectroscopy ◽  
Coronal Magnetic Field ◽  
Microwave Imaging ◽  
Cusp Region

<p>Magnetic reconnection plays a central role in highly magnetized plasma, for example, in solar corona. Release of magnetic energy due to reconnection is believed to drive such transient phenomena as solar flares, eruptions, and jets. This energy release should be associated with a decrease of the coronal magnetic field. Quantitative measurements of the evolving magnetic field strength in the corona are required to find out where exactly and with what rate this decrease takes place. The only available methodology capable of providing such measurements employs microwave imaging spectroscopy of gyrosynchrotron emission from nonthermal electrons accelerated in flares. Here, we report microwave observations of a solar flare, showing spatial and temporal changes in the coronal magnetic field at the cusp region; well below the nominal reconnection X point. The field decays at a rate of ~5 Gauss per second for 2 minutes. This fast rate of decay implies a highly enhanced, turbulent magnetic diffusivity and sufficiently strong electric field to account for the particle acceleration that produces the microwave emission. Moreover, spatially resolved maps of the nonthermal and thermal electron densities derived from the same microwave spectroscopy data set allow us to detect the very acceleration site located within the cusp region. The nonthermal number density is extremely high, while the thermal one is undetectably low in this region indicative of a bulk acceleration process exactly where the magnetic field displays the fast decay. The decrease in stored magnetic energy is sufficient to power the solar flare, including the associated eruption, particle acceleration, and plasma heating. We discuss implications of these findings for understanding particle acceleration in solar flares and in a broader space plasma context.</p>

scholarly journals Changing photospheric vector magnetic fields associated with a B4.2-class solar flare

2012 ◽  
Vol 8 (S294) ◽  
pp. 561-564
Author(s):  
Jiangtao Su ◽  
Yu Liu ◽  
Yuandeng Shen
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Solar Flare ◽  
Solar Flares ◽  
Solar Magnetic Field ◽  
Observational Evidence ◽  
Chinese Academy Of Sciences ◽  
Academy Of Sciences ◽  
Class Flare

AbstractRecent observations have provided evidence that the solar photospheric magnetic fields could have rapid and permanent changes in both longitudinal and transverse components associated with large (X- or M-class) solar flares. However, few observations have been reported about small flares. In this paper we find the observational evidence of changing photospheric vector magnetic fields associated with a B4.2-class flare obtained with the Solar Magnetic Field Telescope (SMFT) installed at Huairou Solar Observing Station (HSOS) of Nation Astronomical Observatories of Chinese Academy of Sciences.

Materials for Electron Beam Information Storage

1969 ◽  
Vol 27 ◽  
pp. 152-153 ◽  
Author(s):  
D. E. Speliotis
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Recent Literature ◽  
Electron Beams ◽  
Information Storage ◽  
The Subject ◽  
The Magnetic Field

The interaction of electron beams with a large variety of materials for information storage has been the subject of numerous proposals and studies in the recent literature. The materials range from photographic to thermoplastic and magnetic, and the interactions with the electron beam for writing and reading the information utilize the energy, or the current, or even the magnetic field associated with the electron beam.

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