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Pre-flare coronal dimmings
Zhang, Q. M.1,2; Su, Y. N.1; Ji, H. S.1
2017-02-01
Source PublicationASTRONOMY & ASTROPHYSICS
ISSN1432-0746
Volume598Pages:6
Corresponding AuthorZhang, Q. M.(hangqm@pmo.ac.cn)
AbstractContext. Coronal dimmings are regions of decreased extreme-ultravoilet (EUV) and/or X-ray (originally Skylab, then Yohkoh/SXT) intensities, which are often associated with flares and coronal mass ejections (CMEs). The large-scale impulsive dimmings have been thoroughly observed and investigated. The pre-flare dimmings before the flare impulsive phase, however, have rarely been studied in detail. Aims. We focus on the pre-flare coronal dimmings. We report our multiwavelength observations of the GOES X1.6 solar flare and the accompanying halo CME that was produced by the eruption of a sigmoidal magnetic flux rope (MFR) in NOAA active region (AR) 12158 on 2014 September 10. Methods. The eruption was observed by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamic Observatory (SDO). The photospheric line-of-sight magnetograms were observed by the Helioseismic and Magnetic Imager (HMI) on board SDO. The soft X-ray (SXR) fluxes were recorded by the GOES spacecraft. The halo CME was observed by the white-light coronagraphs of the Large Angle Spectroscopic Coronagraph (LASCO) on board SOHO. Results. About 96 min before the onset of the flare /CME, narrow pre-flare coronal dimmings appeared at the two ends of the twisted MFR. They extended very slowly, with their intensities decreasing with time, while their apparent widths (8 9 Mm) continued to be nearly constant. During the impulsive and decay phases of flare, typical fan-like twin dimmings appeared and expanded, with a much larger extent and lower intensities than the pre-flare dimmings. The percentage of the 171 angstrom intensity decrease reac40%. The pre-flare dimmings are most striking in 171, 193, and 211 angstrom with formation temperatures 0.6-2.5 MK. The northern part of the pre-flare dimmings could also be recognized in 131 and 335 angstrom. Conclusions. To our knowledge, this is the first detailed study of pre-flare coronal dimmings; they can be explained by density depletion as a result of the gradual expansion of the coronal loop system surrounding the MFR during the slow rise of the MFR.
KeywordSun: corona Sun: coronal mass ejections (CMEs) Sun: flares
DOI10.1051/0004-6361/201629477
WOS KeywordSLIPPING MAGNETIC RECONNECTION ; EXTREME-ULTRAVIOLET WAVE ; MASS EJECTION ; SOLAR-FLARES ; CHROMOSPHERIC EVAPORATION ; FLUX ROPES ; FILAMENT ; DYNAMICS ; ONSET ; EIT
Indexed BySCI
Language英语
WOS Research AreaAstronomy & Astrophysics
WOS SubjectAstronomy & Astrophysics
WOS IDWOS:000394465000003
PublisherEDP SCIENCES S A
Citation statistics
Cited Times:10[WOS]   [WOS Record]     [Related Records in WOS]
Document Type期刊论文
Identifierhttp://libir.pmo.ac.cn/handle/332002/23226
Collection中国科学院紫金山天文台
Corresponding AuthorZhang, Q. M.
Affiliation1.Chinese Acad Sci, Purple Mt Observ, Key Lab Dark Matter & Space Sci, Nanjing 210008, Jiangsu, Peoples R China
2.Chinese Acad Sci, Natl Astron Observ, Key Lab Solar Act, Beijing 100012, Peoples R China
Recommended Citation
GB/T 7714
Zhang, Q. M.,Su, Y. N.,Ji, H. S.. Pre-flare coronal dimmings[J]. ASTRONOMY & ASTROPHYSICS,2017,598:6.
APA Zhang, Q. M.,Su, Y. N.,&Ji, H. S..(2017).Pre-flare coronal dimmings.ASTRONOMY & ASTROPHYSICS,598,6.
MLA Zhang, Q. M.,et al."Pre-flare coronal dimmings".ASTRONOMY & ASTROPHYSICS 598(2017):6.
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