scholarly journals Solar Dynamical Processes II

2019 ◽  
Vol 6 (1) ◽  
pp. 1-13
Author(s):  
Ashish Mishra ◽  
Mukul Kumar
Keyword(s):  
Space Weather ◽  
Coronal Mass Ejections ◽  
Solar Flares ◽  
Interplanetary Space ◽  
Coronal Holes ◽  
High Energy ◽  
Small Scale ◽  
The Sun ◽  
Dynamical Processes ◽  
Wide Range

The present article is the successor of Solar Dynamical Processes I. The previous article was focused on the Sun, its magnetic field with an emphasis on various dynamical processes occurring on the Sun, e.g. sunspots, prominence and bright points which in turn plays a fundamental role in regulating the space weather. This article is emphasized on the solar dynamical processes and develop an extensive understanding of the various phenomena involved in their origin. The article also covers various models and hypothesis put forward by pioneer scientists on the basis of their observation by space-borne and ground-based instruments. This article shade light over a wide range of dynamical processes e.g., solar flares, coronal mass ejections, solar jets and coronal holes. Solar jets, the small-scale transient activities are found to have association with the other transient activities (e.g., mini-flares and mini-filaments). Flares as well as the coronal mass ejections are responsible for releasing a large amount of high energy charged particles and magnetic flux into the interplanetary space, and are being considered as the main drivers of space weather.

scholarly journals Commission 10: Solar Activity

2005 ◽  
Vol 1 (T26A) ◽  
pp. 75-88
Author(s):  
Donald B. Melrose ◽  
James A. Klimchuk ◽  
A.O. Benz ◽  
I.J.D. Craig ◽  
N. Gopalswamy ◽  
...  
Keyword(s):  
Solar Activity ◽  
Space Weather ◽  
Coronal Mass Ejections ◽  
Solar Flares ◽  
Interplanetary Space ◽  
Coronal Loops ◽  
Theoretical Concepts ◽  
Near Earth Space ◽  
Solar Observations ◽  
Extensive List

AbstractCommission 10 aims at the study of various forms of solar activity, including networks, plages, pores, spots, fibrils, surges, jets, filaments/prominences, coronal loops, flares, coronal mass ejections (CMEs), solar cycle, microflares, nanoflares, coronal heating etc., which are all manifestation of the interplay of magnetic fields and solar plasma. Increasingly important is the study of solar activities as sources of various disturbances in the interplanetary space and near-Earth “space weather”.Over the past three years a major component of research on the active Sun has involved data from the RHESSI spacecraft. This review starts with an update on current and planned solar observations from spacecraft. The discussion of solar flares gives emphasis to new results from RHESSI, along with updates on other aspects of flares. Recent progress on two theoretical concepts, magnetic reconnection and magnetic helicity is then summarized, followed by discussions of coronal loops and heating, the magnetic carpet and filaments. The final topic discussed is coronal mass ejections and space weather.The discussions on each topic is relatively brief, and intended as an outline to put the extensive list of references in context.The review was prepared jointly by the members of the Organizing Committee, and the names of the primary contributors to the various sections are indicated in parentheses.

scholarly journals An Insight into Space Weather

2017 ◽  
Vol 2 (1) ◽  
pp. 46-57
Author(s):  
Ashish Mishra ◽  
Mukul Kumar
Keyword(s):  
Solar Wind ◽  
Space Weather ◽  
Solar Flares ◽  
Interplanetary Space ◽  
Power Grids ◽  
The Sun ◽  
Solar Winds ◽  
The Earth ◽  
Earth Connection ◽  
Insight Into

The present article gives a brief overview of space weather and its drivers. The space weather is of immense importance for the spaceborne and ground-based technological systems. The satellites, the power grids, telecommunication and in severe conditions the human lives are at risk. The article covers the effects of solar transient activities (e.g. Solar flares, Coronal mass ejections and Solar winds etc.) and their consequences on the Earth’s atmosphere. The space weather is the change in the conditions of interplanetary space because of the solar transient activities. We also discussed the importance of the solar wind which is a continuous flow of the charged energy particles from the Sun to the Earth in respect of the space weather. This article also put light on the Sun-Earth connection and effects of the space weather on it. The Earth’s magnetosphere, formed by the interaction of solar wind and Earth’s magnetic field behaves like a shield for the Earth against the solar wind.

Study of Stealth CMEs and associated ICMEs

2018 ◽  
Vol 13 (S340) ◽  
pp. 89-90
Author(s):  
Miral Bhatt ◽  
Nandita Srivastava ◽  
Ravindra Jadhav
Keyword(s):  
Magnetic Field ◽  
Coronal Mass Ejections ◽  
Solar Flares ◽  
Interplanetary Space ◽  
The Sun ◽  
Lower Corona ◽  
Flare Loop ◽  
Low Coronal Signatures ◽  
Using Data

AbstractGenerally Coronal Mass Ejections (CMEs) are large eruptions of plasma and magnetic field from the Sun into interplanetary space. CMEs are most frequently associated with a variety of phenomena occurring in the lower corona before, during and after onset of eruption and generally are visible in coronagraph observation. Stealth CMEs do not obviously exhibit any of the low-coronal signatures (LCS) like solar flares, flows, jets, coronal dimmings or brightenings, filament eruptions or the formation of flare loop arcades. In this study, five stealth CMEs are selected using LASCO/SOHO CME catalogue and associated ICMEs (Interplanetaty CMEs) are identified using data from STEREO, ACE and WIND.

Solar Filaments as Tracers of Subsurface Processes

2000 ◽  
Vol 179 ◽  
pp. 177-183
Author(s):  
D. M. Rust
Keyword(s):  
Magnetic Fields ◽  
Magnetic Flux ◽  
Coronal Mass Ejections ◽  
Interplanetary Space ◽  
Intermediate Stage ◽  
Coronal Plasma ◽  
Magnetic Helicity ◽  
The Sun ◽  
New Paradigm ◽  
Solar Filaments

AbstractSolar filaments are discussed in terms of two contrasting paradigms. The standard paradigm is that filaments are formed by condensation of coronal plasma into magnetic fields that are twisted or dimpled as a consequence of motions of the fields’ sources in the photosphere. According to a new paradigm, filaments form in rising, twisted flux ropes and are a necessary intermediate stage in the transfer to interplanetary space of dynamo-generated magnetic flux. It is argued that the accumulation of magnetic helicity in filaments and their coronal surroundings leads to filament eruptions and coronal mass ejections. These ejections relieve the Sun of the flux generated by the dynamo and make way for the flux of the next cycle.

scholarly journals Some kinematics of halo coronal mass ejections

2020 ◽  
Vol 29 (1) ◽  
pp. 81-88
Author(s):  
Virendra Kumar Verma ◽  
Nishant Mittal ◽  
Ramesh Chandra
Keyword(s):  
Coronal Mass Ejections ◽  
Solar Flares ◽  
Coronal Holes ◽  
Geomagnetic Disturbances ◽  
Class A ◽  
Heliospheric Physics ◽  
Class B ◽  
The Mean ◽  
Class C

AbstractWe present an investigation of halo coronal mass ejections (HCMEs) kinematics and other facts about the HCMEs. The study of HCMEs is very important because HCMEs are regarded as the main causes of heliospheric and geomagnetic disturbances. In this study, we have investigated 313 HCMEs observed during 1996-2012 by LASCO, coronal holes, and solar flares. We find that HCMEs are of two types: accelerated HCMEs and decelerated HCMEs. The mean space speed of HCMEs is 1283 km/s while the mean speed of decelerated HCMEs and accelerated HCMEs is 1349 km/s and 1174 km/s, respectively. The investigation shows that 1 (0.3%) HCME was associated with class A SXR, 14 (4.7%) HCMEs were associated with class B SXR-flares, 87 (29.4%) HCMEs were associated with class C SXR-flares, 125 (42.2%) HCMEs were associated with class M SXR-flares and 69 (23.3%) HCMEs were associated with class X SXR-flares. The speed of HCMEs increases with the importance of solar SXR-flares. The various results obtained in the present analysis are discussed in the light of the existing scenario of heliospheric physics.

scholarly journals The Tor Vergata Synoptic Solar Telescope (TSST): A robotic, compact facility for solar full disk imaging

2020 ◽  
Vol 10 ◽  
pp. 58
Author(s):  
Luca Giovannelli ◽  
Francesco Berrilli ◽  
Daniele Calchetti ◽  
Dario Del Moro ◽  
Giorgio Viavattene ◽  
...  
Keyword(s):  
Solar Atmosphere ◽  
Space Weather ◽  
Coronal Mass Ejections ◽  
Low Cost ◽  
Optical Filter ◽  
Solar Telescope ◽  
The Sun ◽  
Weather Events ◽  
Line Observation ◽  
Full Disk

By the continuous multi-line observation of the solar atmosphere, it is possible to infer the magnetic and dynamical status of the Sun. This activity is essential to identify the possible precursors of space weather events, such as flare or coronal mass ejections. We describe the design and assembly of TSST (Tor Vergata Synoptic Solar Telescope), a robotic synoptic telescope currently composed of two main full-disk instruments, a Hα telescope and a Potassium (KI D1) magneto-optical filter (MOF)-based telescope operating at 769.9 nm. TSST is designed to be later upgraded with a second MOF channel. This paper describes the TSST concepts and presents the first light observation carried out in February 2020. We show that TSST is a low-cost robotic facility able to achieve the necessary data for the study of precursors of space weather events (using the magnetic and velocity maps by the MOF telescope) and fast flare detection (by the Hα telescope) to support Space Weather investigation and services.

Solar neutron flux in the energy range 20–160 MeV

1970 ◽  
Vol 48 (18) ◽  
pp. 2155-2161 ◽  
Author(s):  
C. Y. Kim
Keyword(s):  
Neutron Flux ◽  
Energy Range ◽  
Sunspot Number ◽  
Solar Flares ◽  
Energy Region ◽  
High Energy ◽  
The Sun ◽  
Solar Neutron ◽  
Nuclear Emulsions ◽  
The Difference

An attempt to measure the flux of high-energy solar neutrons was made by measuring the difference in flux from the direction of the sun and from the symmetrical direction about the zenith, using oriented nuclear emulsions flown by balloon on July 30, 1966 from Fort Churchill, Manitoba.An excess of (2.2 ± 2.5) × 10−2 neutrons cm−2 s−1 was observed from the direction of the sun in the energy region of 20–160 MeV. On the day of the flight the sunspot number was 63, and no major solar flares were reported.

3D MHD study of the Earth magnetosphere response during extreme space weather conditions

2021 ◽  
Author(s):  
Jacobo Varela Rodriguez ◽  
Sacha A. Brun ◽  
Antoine Strugarek ◽  
Victor Réville ◽  
Filippo Pantellini ◽  
...  
Keyword(s):  
Solar Wind ◽  
Space Weather ◽  
Coronal Mass Ejections ◽  
Main Sequence ◽  
Dynamic Pressure ◽  
Weather Conditions ◽  
The Sun ◽  
Earth Surface ◽  
The Earth ◽  
The Imf

<p><span>The aim of the study is to analyze the response of the Earth magnetosphere for various space weather conditions and model the effect of interplanetary coronal mass ejections. The magnetopause stand off distance, open-closed field lines boundary and plasma flows towards the planet surface are investigated. We use the MHD code PLUTO in spherical coordinates to perform a parametric study regarding the dynamic pressure and temperature of the solar wind as well as the interplanetary magnetic field intensity and orientation. The range of the parameters analyzed extends from regular to extreme space weather conditions consistent with coronal mass ejections at the Earth orbit. The direct precipitation of the solar wind on the Earth day side at equatorial latitudes is extremely unlikely even during super coronal mass ejections. For example, the SW precipitation towards the Earth surface for a IMF purely oriented in the Southward direction requires a IMF intensity around 1000 nT and the SW dynamic pressure above 350 nPa, space weather conditions well above super-ICMEs. The analysis is extended to previous stages of the solar evolution considering the rotation tracks from Carolan (2019). The simulations performed indicate an efficient shielding of the Earth surface 1100 Myr after the Sun enters in the main sequence. On the other hand, for early evolution phases along the Sun main sequence once the Sun rotation rate was at least 5 times faster (< 440 Myr), the Earth surface was directly exposed to the solar wind during coronal mass ejections (assuming today´s Earth magnetic field). Regarding the satellites orbiting the Earth, Southward and Ecliptic IMF orientations are particularly adverse for Geosynchronous satellites, partially exposed to the SW if the SW dynamic pressure is 8-14 nPa and the IMF intensity 10 nT. On the other hand, Medium orbit satellites at 20000 km are directly exposed to the SW during Common ICME if the IMF orientation is Southward and during Strong ICME if the IMF orientation is Earth-Sun or Ecliptic. The same way, Medium orbit satellites at 10000 km are directly exposed to the SW if a Super ICME with Southward IMF orientation impacts the Earth.</span></p><p>This work was supported by the project 2019-T1/AMB-13648 founded by the Comunidad de Madrid, grants ERC WholeSun, Exoplanets A and PNP. We extend our thanks to CNES for Solar Orbiter, PLATO and Meteo Space science support and to INSU/PNST for their financial support.</p>

scholarly journals The role of aerodynamic drag in dynamics of coronal mass ejections

2008 ◽  
Vol 4 (S257) ◽  
pp. 271-277
Author(s):  
Bojan Vršnak ◽  
Dijana Vrbanec ◽  
Jaša Čalogović ◽  
Tomislav Žic
Keyword(s):  
Solar Wind ◽  
Wind Speed ◽  
Coronal Mass Ejections ◽  
Weather Forecasting ◽  
Aerodynamic Drag ◽  
Interplanetary Space ◽  
Solar Wind Speed ◽  
Standard Form ◽  
The Sun

AbstractDynamics of coronal mass ejections (CMEs) is strongly affected by the interaction of the erupting structure with the ambient magnetoplasma: eruptions that are faster than solar wind transfer the momentum and energy to the wind and generally decelerate, whereas slower ones gain the momentum and accelerate. Such a behavior can be expressed in terms of “aerodynamic” drag. We employ a large sample of CMEs to analyze the relationship between kinematics of CMEs and drag-related parameters, such as ambient solar wind speed and the CME mass. Employing coronagraphic observations it is demonstrated that massive CMEs are less affected by the aerodynamic drag than light ones. On the other hand, in situ measurements are used to inspect the role of the solar wind speed and it is shown that the Sun-Earth transit time is more closely related to the wind speed than to take-off speed of CMEs. These findings are interpreted by analyzing solutions of a simple equation of motion based on the standard form for the drag acceleration. The results show that most of the acceleration/deceleration of CMEs on their way through the interplanetary space takes place close to the Sun, where the ambient plasma density is still high. Implications for the space weather forecasting of CME arrival-times are discussed.

scholarly journals Particle Acceleration in Solar Flares and Coronal Mass Ejections

2000 ◽  
Vol 195 ◽  
pp. 15-25
Author(s):  
R. P. Lin
Keyword(s):  
Particle Acceleration ◽  
Energy Release ◽  
Coronal Mass Ejections ◽  
Solar Flares ◽  
Gamma Ray ◽  
Solar Energetic Particle ◽  
High Energy ◽  
Total Rate ◽  
Solar Energetic Particle Events ◽  
High Energy Particles

The Sun accelerates ions up to tens of GeV and electrons up to 100s of MeV in solar flares and coronal mass ejections. The energy in the accelerated tens-of-keV electrons and possibly ~1 MeV ions constitutes a significant fraction of the total energy released in a flare, implying that the particle acceleration and flare energy release mechanisms are intimately related. The total rate of energy release in transients from flares down to microflares/nanoflares may be significant for heating the active solar corona.Shock waves driven by fast CMEs appear to accelerate the high-energy particles in large solar energetic particle events detected at 1 AU. Smaller SEP events are dominated by ~1 to tens-of-keV electrons, with low fluxes of up to a few MeV/nucleon ions, typically enriched in 3He. The acceleration in gamma-ray flares appears to resemble that in these small electron-3He SEP events.

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