scholarly journals Submillimeter and Far Infrared Emission from Solar Flares

1994 ◽  
Vol 154 ◽  
pp. 103-112
Author(s):  
Vahé Petrosian
Keyword(s):  
Brightness Temperature ◽  
Solar Flares ◽  
Gamma Ray ◽  
Far Infrared ◽  
Impulsive Phase ◽  
Infrared Emission ◽  
Synchrotron Emission ◽  
X Ray ◽  
Quiet Sun ◽  
Hot Plasma

The mechanisms for emission in the submillimeter and far-infrared (1011 and 1013 Hz) regions by solar flares and expected fluxes at these frequencies are described and evaluated. These inferences are based on observations of flare emission at other frequencies and on models for these emissions. In the impulsive phase, non-thermal synchrotron emission by electrons responsible for > 10 MeV gamma-ray emission can give rise to significant radiation in the 1011 to 1013 Hz region from large flares. Free-free or thermal gyrosynchrotron from the hot plasma responsible for the gradual soft X-ray emission can produce significant radiation in the 1011 to 1013 Hz range. However, only radiation in the lower end of this range would have a brightness temperature exceeding the quiet sun brightness.

scholarly journals SolpeX: the soft X-ray flare polarimeter–spectrometer for the ISS

2014 ◽  
Vol 10 (S305) ◽  
pp. 114-120
Author(s):  
Janusz Sylwester ◽  
Stefan Płocieniak ◽  
Jarosław Bakała ◽  
Żaneta Szaforz ◽  
Marek Stȩślicki ◽  
...  
Keyword(s):  
Solar Flares ◽  
Line Emission ◽  
Impulsive Phase ◽  
Particle Beams ◽  
X Ray ◽  
Hot Plasma ◽  
Spectral Imager ◽  
Polarized Bremsstrahlung ◽  
Made In ◽  
Fast Rotating

AbstractWe present the innovative soft X-ray spectro-polarimeter, SolpeX. This instrument consists of three functionally independent blocks. They are to be included into the Russian instrument KORTES, to be mounted onboard the ISS. The three SolpeX units are: a simple pin-hole X-ray spectral imager, a polarimeter, and a fast-rotating drum multiple-flat-crystal Bragg spectrometer. Such a combination of measuring blocks will offer a new opportunity to reliably measure possible X-ray polarization and spectra of solar flares, in particular during the impulsive phase. Polarized Bremsstrahlung and line emission due to the presence of directed particle beams will be detected, and measurements of the velocities of evaporated hot plasma will be made. In this paper we discuss the details of the construction of the SolpeX units. The delivery of KORTES with SolpeX to the ISS is expected to happen in 2017/2018.

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 Turbulent Acceleration in Solar Flares

1994 ◽  
Vol 142 ◽  
pp. 623-630
Author(s):  
D. B. Melrose
Keyword(s):  
Solar Flares ◽  
Gamma Ray ◽  
Low Frequency ◽  
Impulsive Phase ◽  
Primary Energy ◽  
Nonthermal Electron ◽  
Relativistic Electrons ◽  
Mhd Turbulence ◽  
Narrow Channels ◽  
Current Instability

AbstractTurbulent acceleration in the impulsive phase of solar flares is reviewed, with the emphasis on bulk energization of nonrelativistic electrons and prompt acceleration of the gamma-ray emitting nonrelativistic ions and relativistic electrons. The primary energy release in a flare cannot be due to collisional dissipation. Anomalous resistivity requires that the current flows in many narrow channels with the current density above threshold for current instability. The bulk energization of the electrons is due to the damping of low-frequency electrostatic turbulence generated by the current instability. This turbulence also limits the rate a nonthermal electron tail forms due to runaway acceleration. Stochastic and gyroresonant acceleration by MHD turbulence are discussed briefly, emphasizing the need for preacceleration. Stochastic acceleration is favorable for the gamma-ray emitting particles only if an adequated source of the MHD turbulence can be identified.Subject headings: acceleration of particles — MHD — Sun: flares — turbulence

scholarly journals HXR photospheric footprints

2007 ◽  
Vol 3 (S247) ◽  
pp. 110-113
Author(s):  
J. C. Martínez-Oliveros ◽  
A.-C. Donea ◽  
P. S. Cally
Keyword(s):  
Solar Flares ◽  
Acoustic Waves ◽  
Neutral Line ◽  
Impulsive Phase ◽  
Coronal Loops ◽  
Direct Link ◽  
Constructive Interference ◽  
X Ray ◽  
Hydrodynamic Response ◽  
Relativistic Particles

AbstractWe have analysed the 6 mHz egression power signatures of some accoustically active X-class solar flares. During the impulsive phase these flares produced conspicuous seismic signatures which have kernel-like structures, mostly aligned with the neutral line of the host active region. The kernel-like structures show the effect of constructive interference of the acoustic waves emanating from the complex sources, suggesting motion of the acoustic sources. The co-aligment between the seismic signatures and the hard X-ray emission observed by RHESSI from the footpoints of the coronal loops suggests a direct link between relativistic particles accelerated during the flare and the hydrodynamic response of the photosphere during flares.

On the hard X-ray spatial structure during the impulsive phase of solar flares

Solar Physics ◽  
1987 ◽  
Vol 107 (2) ◽  
pp. 263-269 ◽  
Author(s):  
A. Gordon Emslie ◽  
Marcos E. Machado
Keyword(s):  
Spatial Structure ◽  
Solar Flares ◽  
Impulsive Phase ◽  
X Ray

Development of a hard X-ray polarimeter for solar flares and gamma-ray bursts

1998 ◽  
Vol 45 (3) ◽  
pp. 910-914 ◽  
Author(s):  
M.L. McConnell ◽  
D.J. Forrest ◽  
J. Macri ◽  
M. McClish ◽  
M. Osgood ◽  
...  
Keyword(s):  
Solar Flares ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
X Ray

Observations of gamma-ray spectra and X-ray images of solar flares

1996 ◽  
Author(s):  
M. Yoshimori ◽  
K. Morimoto ◽  
K. Suga ◽  
T. Matsuda ◽  
N. Saita
Keyword(s):  
Solar Flares ◽  
Gamma Ray ◽  
X Ray

Characteristics of Sunquake Events Observed in Solar Cycle 24

2021 ◽  
Author(s):  
Alexander Kosovichev ◽  
Ivan Sharykin
Keyword(s):  
Solar Cycle ◽  
Solar Flares ◽  
Active Regions ◽  
Impulsive Phase ◽  
High Energy ◽  
Lower Atmosphere ◽  
Solar Dynamics Observatory ◽  
X Ray ◽  
Solar Cycle 24 ◽  
Cycle 24

<p>Helioseismic response to solar flares ("sunquakes") occurs due to localized force or/and momentum impacts observed during the flare impulsive phase in the lower atmosphere. Such impacts may be caused by precipitation of high-energy particles, downward shocks, or magnetic Lorentz force. Understanding the mechanism of sunquakes is a key problem of the flare energy release and transport. Our statistical analysis of M-X class flares observed by the Solar Dynamics Observatory during Solar Cycle 24 has shown that contrary to expectations, many relatively weak M-class flares produced strong sunquakes, while for some powerful X-class flares, helioseismic waves were not observed or were weak. The analysis also revealed that there were active regions characterized by the most efficient generation of sunquakes during the solar cycle. We found that the sunquake power correlates with maximal values of the X-ray flux derivative better than with the X-ray class. The sunquake data challenge the current theories of solar flares.</p>

Sign in / Sign up

Export Citation Format

Share Document