The sun and solar flares

1982 ◽  
Vol 17 (4) ◽  
pp. 165-173
Author(s):  
S McKenna-Lawlor
Keyword(s):  
Solar Flares ◽  
The Sun

scholarly journals Hydrodynamic Models of Solar and Stellar Flares

1989 ◽  
Vol 104 (1) ◽  
pp. 289-298
Author(s):  
Giovanni Peres
Keyword(s):  
High Resolution ◽  
Light Curve ◽  
Solar Flares ◽  
Impulsive Phase ◽  
Light Curves ◽  
Physical Parameters ◽  
The Sun ◽  
Hydrodynamic Models ◽  
X Ray ◽  
Stellar Flares

AbstractThis paper discusses the hydrodynamic modeling of flaring plasma confined in magnetic loops and its objectives within the broader scope of flare physics. In particular, the Palermo-Harvard model is discussed along with its applications to the detailed fitting of X-ray light curves of solar flares and to the simulation of high-resolution Caxix spectra in the impulsive phase. These two approaches provide complementary constraints on the relevant features of solar flares. The extension to the stellar case, with the fitting of the light curve of an X-ray flare which occurred on Proxima Centauri, demonstrates the feasibility of using this kind of model for stars too. Although the stellar observations do not provide the wealth of details available for the Sun, and, therefore, constrain the model more loosely, there are strong motivations to pursue this line of research: the wider range of physical parameters in stellar flares and the possibility of studying further the solar-stellar connection.

scholarly journals Radio imaging-spectroscopy observations of the Sun in decimetric and centimetric wavelengths

2012 ◽  
Vol 8 (S294) ◽  
pp. 489-494 ◽  
Author(s):  
Yihua Yan ◽  
Wei Wang ◽  
Fei Liu ◽  
Lihong Geng ◽  
Zhijun Chen ◽  
...  
Keyword(s):  
Radio Emission ◽  
Solar Flares ◽  
Inner Mongolia ◽  
Imaging Spectroscopy ◽  
Current Status ◽  
The Sun ◽  
Radio Imaging ◽  
Time Space ◽  
Decimetric Wave ◽  
Wave Range

AbstractTo address fundamental processes in the solar eruptive phenomena it is important to have imaging-spectroscopy over centimetric-decimetric wave range. The Chinese Spectral Radioheliograph (CSRH) in 0.4-15 GHz range with high time, space and frequency resolutions is being constructed to achieve this goal. The perspectives to open new observational windows on solar flares and CMEs will be achieved by mapping the radio emission from unstable electron populations during the basic processes of energy release. CSRH is located in a radio quiet region in Inner Mongolia of China. The array of CSRH-I in 0.4-2.0 GHz with 40 4.5m antennas has been established and starts test observations. The 60 2m antennas for array of CSRH-II in 2-15 GHz have been mounted and assembled. The progress and current status of CSRH are introduced.

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.

scholarly journals Millimeter and Microwave Activity of the Sun

1990 ◽  
Vol 142 ◽  
pp. 457-465 ◽  
Author(s):  
M. R. Kundu ◽  
S. M. White
Keyword(s):  
Magnetic Field ◽  
Gamma Rays ◽  
Solar Flares ◽  
Gamma Ray ◽  
High Spatial Resolution ◽  
High Resolution Imaging ◽  
The Sun ◽  
Millimeter Wavelengths ◽  
Resolution Imaging ◽  
The Magnetic Field

The emission of solar flares at millimeter wavelengths is of great interest both in its own right and because it is generated by the energetic electrons which also emit gamma rays. Since high-resolution imaging at gamma-ray energies is not presently possible, millimeter observations can act as a substitute. Except for that class of flares known as gamma-ray flares the millimetric emission is optically thin. It can be used as a powerful diagnostic of the energy distribution of electrons in solar flares and its evolution, and of the magnetic field. We have carried out high-spatial-resolution millimeter observations of solar flares this year using the Berkeley-Illinois-Maryland Array (BIMA), and report on the preliminary results in this paper (Kundu et al 1990; White et al 1990). We also report some recent results obtained from multifrequency observations using the VLA (White et al 1990).

scholarly journals Tidal Force of Sun Due to Planetary Radial Alignment and Sun-Spot Cycle

1993 ◽  
Vol 132 ◽  
pp. 407-414
Author(s):  
S.D. Verma
Keyword(s):  
Sunspot Number ◽  
Solar Flares ◽  
Tidal Force ◽  
Solar Photosphere ◽  
Neutral Atmosphere ◽  
The Sun ◽  
Cycle Number ◽  
Long Time ◽  
Small Force ◽  
Periodic Changes

AbstractIt is well known that the Sun’s radiation and a large number of phenomena occurring on the sun have influence on the Earth’s near environment i.e. Atmosphere, Ionosphere, Magnetosphere, etc. These manifest themselves as day-night, seasons, tides and many changes in the neutral atmosphere; changes in meteorological parameters. These changes are directly or indirectly related to variations in solar parameters, such as solar flares, magnetic storms, variations in sunspot number occurring in solar photosphere. Sunsports are observed, their number counted and their accurate records maintained for long time (many centuaries). The sunspot number seems to follow periodic changes with several periods; mainly 11 years and 23.5 years. Recently it has been shown that the combined tidal force of the inner planets and two largest planets, Jupiter and Saturn, have periodic change of 11 and 23.5 years. It was proposed that this small force may be having a tiny influence on the surface of the Sun and causing some nonlinear effect which results into formation of sunspots and thus causes the variations in the number of sunspots. In the present work it is shown that whenever the combined tidal force on sun increases then sunspot number seems to increase and when force decreases sunspot number decreases. This is shown for Solar Cycle number 21.

scholarly journals Solar Flares, the Solar Corona, and Solar Physics

2000 ◽  
Vol 195 ◽  
pp. 455-459
Author(s):  
E. N. Parker
Keyword(s):  
Quantum Mechanics ◽  
Solar Corona ◽  
Solar Flares ◽  
Solar Physics ◽  
The Sun ◽  
Classical Physics ◽  
Physics Laboratory ◽  
Physical Effects

The Sun serves as the local physics laboratory for studying the suprathermal activity phenomena of stars. Scrutiny of the Sun has led to the discovery of a host of previously unknown physical effects, largely within the classical physics of Newton and Maxwell, but including quantum mechanics and lepton physics as well.

scholarly journals Investigation of the Sudden Solar Ionospheric Disturbance using Radio Telescope

2020 ◽  
Vol 240 ◽  
pp. 07003
Author(s):  
Adam Aqasha ◽  
Andrien Zheng ◽  
Sneha Athreya ◽  
Hoe Teck Tan
Keyword(s):  
Solar Flares ◽  
Solar Minimum ◽  
Solar Maximum ◽  
Ionospheric Disturbance ◽  
Low Frequency ◽  
The Sun ◽  
Radio Telescopes ◽  
Very Low Frequency ◽  
Set Up ◽  
Vlf Waves

Low-frequency radio telescopes are cheap and useful devices for the investigation of terrestrial and extra-terrestrial emissions. These emissions come either from the Sun and the planet Jupiter to terrestrial emissions. This project aims to investigate the Very Low Frequency (VLF) waves from mid-August to October 2019 using Radio JOVE (20 MHz) and SSID (3-30 kHz) to observe for the occurrence of solar flares and see how if the radio telescopes that the team set up is reliable. This will allow us future students aspiring to learn about astronomy to examine solar flares in detail during the upcoming solar maximum. Not many flares were detected as this period happens to be a solar minimum. However, a series of flares occurred between 30 September 2019 and 1 October 2019, which the telescopes have been able to detect, particularly SSID.

High-Energy Solar Gamma-Ray Observations

1998 ◽  
Vol 11 (2) ◽  
pp. 755-758
Author(s):  
M. Yoshimori ◽  
N. Saita ◽  
A. Shiozawa
Keyword(s):  
Particle Acceleration ◽  
Gamma Rays ◽  
Solar Flares ◽  
Gamma Ray ◽  
Solar Maximum ◽  
High Energy ◽  
The Sun ◽  
Long Duration ◽  
New Findings ◽  
Gamma Ray Emission

In the last solar maximum, gamma-rays associated with solar flares were observed with GRANAT, GAMMA-1, CGRO and YOHKOH. The gamma-ray energies ranged from 100 keV to a few GeV. We obtained several new findings of gamma-ray emission on the Sun: (1) Gamma-ray production in the corona, (2) GeV gamma-ray production in very long duration flares, (3) Electron-rich flares, (4) Gamma-ray lines and solar atmospheric abundances and (5) Possible location of gamma-ray emission. We present the observations of these new findings and discuss high energy phenomena relating to particle acceleration and gamma-ray production during solar flares.

scholarly journals Solar flares as proxy for the young Sun: satellite observed thermosphere response to an X17.2 flare of Earth's upper atmosphere

2012 ◽  
Vol 30 (8) ◽  
pp. 1129-1141 ◽  
Author(s):  
S. Krauss ◽  
B. Fichtinger ◽  
H. Lammer ◽  
W. Hausleitner ◽  
Yu. N. Kulikov ◽  
...  
Keyword(s):  
Solar Flares ◽  
Radiation Flux ◽  
Extreme Ultraviolet ◽  
Upper Atmosphere ◽  
Radiation Environment ◽  
The Sun ◽  
Satellite Drag ◽  
Grace Satellites ◽  
Early Phases ◽  
Activity Indices

Abstract. We analyzed the measured thermospheric response of an extreme solar X17.2 flare that irradiated the Earth's upper atmosphere during the so-called Halloween events in late October/early November 2003. We suggest that such events can serve as proxies for the intense electromagnetic and corpuscular radiation environment of the Sun or other stars during their early phases of evolution. We applied and compared empirical thermosphere models with satellite drag measurements from the GRACE satellites and found that the Jacchia-Bowman 2008 model can reproduce the drag measurements very well during undisturbed solar conditions but gets worse during extreme solar events. By analyzing the peak of the X17.2 flare spectra and comparing it with spectra of young solar proxies, our results indicate that the peak flare radiation flux corresponds to a hypothetical Sun-like star or the Sun at the age of approximately 2.3 Gyr. This implies that the peak extreme ultraviolet (EUV) radiation is enhanced by a factor of about 2.5 times compared to today's Sun. On the assumption that the Sun emitted an EUV flux of that magnitude and by modifying the activity indices in the Jacchia-Bowman 2008 model, we obtain an average exobase temperature of 1950 K, which corresponds with previous theoretical studies related to thermospheric heating and expansion caused by the solar EUV flux.

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