34802
2013
2013
eng
13
2
773
article
IOP Publ. Ltd.
Bristol
1
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Observation of a moretown wave and wave-filament interactions associated with the renowned X9 flare on 1990 May 24
Using Big Bear Solar Observatory film data recently digitized at NJIT, we investigate a Moreton wave associated with an X9 flare on 1990 May 24, as well as its interactions with four filaments F1-F4 located close to the flaring region. The interaction yields interesting insight into physical properties of both the wave and the filaments. The first clear Moreton wavefront appears at the flaring-region periphery at approximately the same time as the peak of a microwave burst and the first of two gamma-ray peaks. The wavefront propagates at different speeds ranging from 1500-2600 km s(-1) in different directions, reaching as far as 600 Mm away from the flaring site. Sequential chromospheric brightenings are observed ahead of the Moreton wavefront. A slower diffuse front at 300-600 km s(-1) is observed to trail the fast Moreton wavefront about one minute after the onset. The Moreton wave decelerates to similar to 550 km s(-1) as it sweeps through F1. The wave passage results in F1's oscillation which is featured by similar to 1 mHz signals with coherent Fourier phases over the filament, the activation of F3 and F4 followed by gradual recovery, but no disturbance in F2. Different height and magnetic environment together may account for the distinct responses of the filaments to the wave passage. The wavefront bulges at F4, whose spine is oriented perpendicular to the upcoming wavefront. The deformation of the wavefront is suggested to be due to both the forward inclination of the wavefront and the enhancement of the local Alfven speed within the filament channel.
The astrophysical journal : an international review of spectroscopy and astronomical physics
10.1088/0004-637X/773/2/166
0004-637X
wos:2011-2013
166
WOS:000323426100085
Liu, R (reprint author), Univ Sci & Technol China, Dept Geophys & Planetary Sci, CAS Key Lab Geospace Environm, Hefei 230026, Peoples R China., rliu@ustc.edu.cn
NSF [AGS 0839216, AGS 0849453, AGS-1153226, AGS-1153424]; Thousand Young
Talents Program of China; NSFC [41222031, 41131065, 41121003]; 973 key
project [2011CB811403]; CAS [KZZD-EW-01-4]; fundamental research funds
for the central universities [WK2080000031]; DFG; STFC; Chinese Academy
of Sciences [2012T1J0017]
Rui Liu
Chang Liu
Yan Xu
Wei Liu
Bernhard Kliem
Haimin Wang
eng
uncontrolled
Sun: filaments, prominences
eng
uncontrolled
Sun: flares
eng
uncontrolled
Sun: oscillations
eng
uncontrolled
waves
Institut für Physik und Astronomie
Referiert
45603
2016
2016
eng
22
818
article
IOP Publ. Ltd.
Bristol
1
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STRUCTURE, STABILITY, AND EVOLUTION OF MAGNETIC FLUX ROPES FROM THE PERSPECTIVE OF MAGNETIC TWIST
We investigate the evolution of NOAA Active Region (AR) 11817 during 2013 August 10–12, when it developed a complex field configuration and produced four confined, followed by two eruptive, flares. These C-and-above flares are all associated with a magnetic flux rope (MFR) located along the major polarity inversion line, where shearing and converging photospheric flows are present. Aided by the nonlinear force-free field modeling, we identify the MFR through mapping magnetic connectivities and computing the twist number ${{ \mathcal T }}_{w}$ for each individual field line. The MFR is moderately twisted ($| {{ \mathcal T }}_{w}| \lt 2$) and has a well-defined boundary of high squashing factor Q. We found that the field line with the extremum $| {{ \mathcal T }}_{w}| $ is a reliable proxy of the rope axis, and that the MFR's peak $| {{ \mathcal T }}_{w}| $ temporarily increases within half an hour before each flare while it decreases after the flare peak for both confined and eruptive flares. This pre-flare increase in $| {{ \mathcal T }}_{w}| $ has little effect on the AR's free magnetic energy or any other parameters derived for the whole region, due to its moderate amount and the MFR's relatively small volume, while its decrease after flares is clearly associated with the stepwise decrease in the whole region's free magnetic energy due to the flare. We suggest that ${{ \mathcal T }}_{w}$ may serve as a useful parameter in forewarning the onset of eruption, and therefore, the consequent space weather effects. The helical kink instability is identified as the prime candidate onset mechanism for the considered flares.
The astrophysical journal : an international review of spectroscopy and astronomical physics
10.3847/0004-637X/818/2/148
0004-637X
1538-4357
wos2016:2019
148
WOS:000372302800047
Liu, R (reprint author), Univ Sci & Technol China, Dept Geophys & Planetary Sci, CAS Key Lab Geospace Environm, Hefei 230026, Peoples R China.; Liu, R (reprint author), Collaborat Innovat Ctr Astronaut Sci & Technol, Hefei 230026, Peoples R China., rliu@ustc.edu.cn
Thousand Young Talents Program of China, NSFC [41222031, 41474151]; NSFC [41131065]; CAS [KZZD-EW-01-4, 2012T1J0017]; fundamental research funds for the central universities; DFG; NSF SHINE program; NSF [AGS 1348513, 1408703]; NASA [NNX13AG13G, NNX13AF76G]
importub
2020-03-22T19:55:01+00:00
filename=package.tar
c286dd75d0f30aecbb7b257750b890ab
Rui Liu
Bernhard Kliem
Viacheslav S. Titov
Jun Chen
Yuming Wang
Haimin Wang
Chang Liu
Yan Xu
Thomas Wiegelmann
eng
uncontrolled
coronal mass ejections (CMEs)
eng
uncontrolled
Sun: corona
eng
uncontrolled
Sun: filaments, pominences
eng
uncontrolled
Sun: flares
eng
uncontrolled
Sun: magnetic fields
Institut für Physik und Astronomie
Referiert
Import