Type II?IV radio bursts and compact and diffuse white-light clouds in the outer corona of December 14, 1971

Solar Physics ◽  
1976 ◽  
Vol 48 (2) ◽  
pp. 339-356 ◽  
Author(s):  
Takeo Kosugi
Keyword(s):  
White Light ◽  
Radio Bursts ◽  
Type Ii ◽  
Outer Corona

Radio Observations of a Massive, Slow-Moving Ejection of Coronal Material

1978 ◽  
Vol 3 (4) ◽  
pp. 249-250 ◽  
Author(s):  
K. V. Sheridan ◽  
B. V. Jackson ◽  
D. J. McLean ◽  
G. A. Dulk
Keyword(s):  
White Light ◽  
Fast Moving ◽  
Radio Bursts ◽  
Type Ii ◽  
Radio Observations ◽  
Quiet Sun ◽  
Slow Moving

Studies of coronal transients observed in white-light (Gosling et al., 1976) have shown that fast-moving events (≤ 400 km s-1) are closely associated with flares and with type II and IV radio bursts while slow-moving events are not. We now report the first detection of the radio counterpart of a slow-moving transient. The event of 1974 January 21 is shown to be visible on maps of the quiet Sun made at a frequency of 80 MHz.

scholarly journals K2 Ultracool Dwarfs Survey – VI. White light superflares observed on an L5 dwarf and flare rates of L dwarfs

2020 ◽  
Vol 494 (4) ◽  
pp. 5751-5760 ◽  
Author(s):  
R R Paudel ◽  
J E Gizis ◽  
D J Mullan ◽  
S J Schmidt ◽  
A J Burgasser ◽  
...  
Keyword(s):  
White Light ◽  
Observation Time ◽  
Radio Bursts ◽  
Type Ii ◽  
Photospheric Level ◽  
Type Ii Radio Bursts ◽  
Total Observation Time ◽  
L Dwarfs ◽  
Total Observation ◽  
Flare Frequency

ABSTRACT $Kepler\, K2$ long cadence data are used to study white light flares in a sample of 45 L dwarfs. We identified 11 flares on 9 L dwarfs with equivalent durations of (1.3–198) h and total (UV/optical/IR) energies of ≥0.9 × 1032 erg. Two superflares with energies of >1033 erg were detected on an L5 dwarf (VVV BD001): this is the coolest object so far on which flares have been identified. The larger superflare on this L5 dwarf has an energy of 4.6 × 1034 erg and an amplitude of >300 times the photospheric level: so far, this is the largest amplitude flare detected by the Kepler/K2 mission. The next coolest star on which we identified a flare was an L2 dwarf: 2MASS J08585891+1804463. Combining the energies of all the flares which we have identified on 9 L dwarfs with the total observation time which was dedicated by Kepler to all 45 L dwarfs, we construct a composite flare frequency distribution (FFD). The FFD slope is quite shallow (−0.51 ± 0.17), consistent with earlier results reported by Paudel et al. for one particular L0 dwarf, for which the FFD slope was found to be −0.34. Using the composite FFD, we predict that, in early- and mid-L dwarfs, a superflare of energy 1033 erg occurs every 2.4 yr and a superflare of energy 1034 erg occurs every 7.9 yr. Analysis of our L dwarf flares suggests that magnetic fields of ≥0.13–1.3 kG are present on the stellar surface: such fields could suppress Type II radio bursts.

Type II Solar Radio Bursts over Solar Cycle 21

1994 ◽  
Vol 144 ◽  
pp. 283-284
Author(s):  
G. Maris ◽  
E. Tifrea
Keyword(s):  
Solar Radio ◽  
Interplanetary Space ◽  
Impulsive Phase ◽  
Radio Bursts ◽  
Type Ii ◽  
Solar Radio Bursts ◽  
Strong Energy ◽  
Mass Ejection ◽  
Geophysical Effect ◽  
Radio Event

The type II solar radio bursts produced by a shock wave passing through the solar corona are one of the most frequently studied solar activity phenomena. The scientific interest in this type of phenomenon is due to the fact that the presence of this radio event in a solar flare is an almost certain indicator of a future geophysical effect. The origin of the shock waves which produce these bursts is not at all simple; besides the shocks which are generated as a result of a strong energy release during the impulsive phase of a flare, there are also the shocks generated by a coronal mass ejection or the shocks which appear in the interplanetary space due to the supplementary acceleration of the solar particles.

Solar and interplanetary parameters of CMEs with and without type II radio bursts

2012 ◽  
Vol 50 (4) ◽  
pp. 516-525 ◽  
Author(s):  
A. Mujiber Rahman ◽  
S. Umapathy ◽  
A. Shanmugaraju ◽  
Y.-J. Moon
Keyword(s):  
Radio Bursts ◽  
Type Ii ◽  
Type Ii Radio Bursts

scholarly journals Coronal electron density distributions estimated from CMEs, DH type II radio bursts, and polarized brightness measurements

2016 ◽  
Vol 121 (4) ◽  
pp. 2853-2865 ◽  
Author(s):  
Jae‐Ok Lee ◽  
Y.‐J. Moon ◽  
Jin‐Yi Lee ◽  
Kyoung‐Sun Lee ◽  
R.‐S. Kim
Keyword(s):  
Electron Density ◽  
Radio Bursts ◽  
Type Ii ◽  
Density Distributions ◽  
Type Ii Radio Bursts ◽  
Coronal Electron

Investigation of X-class Flare-Associated Coronal Mass Ejections with and without DH Type II Radio Bursts

Solar Physics ◽  
2015 ◽  
Vol 290 (11) ◽  
pp. 3365-3377 ◽  
Author(s):  
M. Bendict Lawrance ◽  
A. Shanmugaraju ◽  
Bojan Vršnak
Keyword(s):  
Coronal Mass Ejections ◽  
Radio Bursts ◽  
Type Ii ◽  
Type Ii Radio Bursts ◽  
Class Flare

Fine structure of decametric type II radio bursts

2007 ◽  
Vol 33 (3) ◽  
pp. 192-202 ◽  
Author(s):  
G. P. Chernov ◽  
A. A. Stanislavsky ◽  
A. A. Konovalenko ◽  
E. P. Abranin ◽  
V. V. Dorovsky ◽  
...  
Keyword(s):  
Fine Structure ◽  
Radio Bursts ◽  
Type Ii ◽  
Type Ii Radio Bursts

scholarly journals Optical Observations of the Solar Disturbances Causing Type II Radio Bursts

1958 ◽  
Vol 11 (3) ◽  
pp. 353 ◽  
Author(s):  
RG Giovanelli ◽  
JA Roberts
Keyword(s):  
Subsequent Development ◽  
Optical Observations ◽  
Radio Bursts ◽  
Type Ii ◽  
Type Ii Radio Bursts ◽  
Solar Disturbances ◽  
Dark Filament

Identifications have been established for the solar optical events associated with a number of type II radio bursts. Near or at the limb these have been ejections with velocities exceeding that of sound in the corona. Where the event has been on the disk there has usually been a very bright flare, with some evidence of dark filament activity. In two cases the event was the disappearance (i.e. ejection) of a filament with the subsequent development of flares on either side.

scholarly journals Analyzing the propagation of EUV waves and their connection with type II radio bursts by combining numerical simulations and multi-instrument observations

2020 ◽  
Vol 644 ◽  
pp. A90
Author(s):  
A. Koukras ◽  
C. Marqué ◽  
C. Downs ◽  
L. Dolla
Keyword(s):  
Magnetic Field ◽  
Wave Front ◽  
Ray Tracing ◽  
Radio Burst ◽  
Radio Bursts ◽  
Type Ii ◽  
Fast Mode ◽  
Type Ii Radio Bursts ◽  
The Magnetic Field ◽  
Burst Emission

Context. EUV (EIT) waves are wavelike disturbances of enhanced extreme ultraviolet (EUV) emission that propagate away from an eruptive active region across the solar disk. Recent years have seen much debate over their nature, with three main interpretations: the fast-mode magneto-hydrodynamic (MHD) wave, the apparent wave (reconfiguration of the magnetic field), and the hybrid wave (combination of the previous two). Aims. By studying the kinematics of EUV waves and their connection with type II radio bursts, we aim to examine the capability of the fast-mode interpretation to explain the observations, and to constrain the source locations of the type II radio burst emission. Methods. We propagate a fast-mode MHD wave numerically using a ray-tracing method and the WKB (Wentzel-Kramers-Brillouin) approximation. The wave is propagated in a static corona output by a global 3D MHD Coronal Model, which provides density, temperature, and Alfvén speed in the undisturbed coronal medium (before the eruption). We then compare the propagation of the computed wave front with the observed wave in EUV images (PROBA2/SWAP, SDO/AIA). Lastly, we use the frequency drift of the type II radio bursts to track the propagating shock wave, compare it with the simulated wave front at the same instant, and identify the wave vectors that best match the plasma density deduced from the radio emission. We apply this methodology for two EUV waves observed during SOL2017-04-03T14:20:00 and SOL2017-09-12T07:25:00. Results. The simulated wave front displays a good qualitative match with the observations for both events. Type II radio burst emission sources are tracked on the wave front all along its propagation. The wave vectors at the ray-path points that are characterized as sources of the type II radio burst emission are quasi-perpendicular to the magnetic field. Conclusions. We show that a simple ray-tracing model of the EUV wave is able to reproduce the observations and to provide insight into the physics of such waves. We provide supporting evidence that they are likely fast-mode MHD waves. We also narrow down the source region of the radio burst emission and show that different parts of the wave front are responsible for the type II radio burst emission at different times of the eruptive event.

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