a large-scale darkening observed in euv and radio emissions
DESCRIPTION
A large-scale darkening observed in EUV and radio emissions. V. Grechnev, A. Uralov, I. Kuzmenko, I. Chertok et al. SOHO/EIT 304 Å. Before, during, and after. 2004 July 13. SOHO/EIT 195 Å & LASCO/C2. SOHO telescopes show an eruptive event:. 00:16:50. 00:48:08. 00:07:52. 00:19:42. - PowerPoint PPT PresentationTRANSCRIPT
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NBYM 2006
A large-scale darkening observed in EUV and radio
emissions
V. Grechnev, A. Uralov, I. Kuzmenko, I. Chertok et
al.
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SOHO/EIT 304 ÅBefore, during, and after
2004 July 13
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SOHO/EIT 195 Å & LASCO/C2
SOHO telescopes show an eruptive event:
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TRACE 171 Å 00:07:5
200:13:37
00:16:50
00:19:42
00:21:36
00:48:08
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Big Bear H images
Flare and eruptive filament
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Mauna Loa H imagesOriginal image
Fixed-base difference
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2004 July 13 event: GOES M6.7 in AR 10646 (N15W49) Very impulsive microwave burst
Flux 1200 sfu @ 17 GHz Duration ~10 min
H flare not reported by patrol stations but Big Bear images show it
Filament eruption and CME
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304 ÅProbable causes of large darkening in HeII 304 Å
1. Dimming due to density depletion? – Usually well observed in 195 Å
2. Occultation by absorbing material: resonant absorption in cooler HeII
(<50000 K)? non-resonant absorption in H (<10000
K)?
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Evolution of 195 Å dimming
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Summary on 195 Å dimming
Density-depletion 195 Å dimming lives much longer
Configuration quite different Not a density-depletion dimming
Min{Images} Images[0] Min{Images}/ Images[0]
304 Å
195 195 ÅÅ
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NoRH shows Ejected material: First bright on the disk Then bright above the
limb, and dark on the disk
Dark moving feature is not large
Ejecta is inhomogeneous
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Multi-frequency radio fluxes
EIT 304 Åobservation
NoRP & Ussuriysk 2.8 GHz
Solid: observed Dotted: thermal emission
of flare subtracted Normalized to the quiet
sun’s level Absorption TFil < TQS 3.75 = 23,000 K
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Frequency dependence of radio absorption
Symbols: observed Solid: calculated
considering the ejecta and corona above it
Ejected mass (6–9)·1015 g with depth = (20–200) Mm
, GHz
AreaEIT304=0.067
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Epilogue-I The phenomenon was due to occultation
of the quiet sun rather than an active region
This unique event was revealed from EIT 304 Å data and independently from Ussuriysk 10.7 cm records
It was possible to detect it from total flux radio records thanks to shortness of the main burst
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Epilogue-II Murphy’s Low works perfectly:
No SSRT 5.7 GHz data No high-cadence CORONAS-F/SPIRIT 304 Å
data…Which would be important…
Nevertheless, non-imaging multi-frequency total flux records allowed us to study the event
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We acknowledge Shibasaki San and NSRO for
the opportunity to work here under perfect conditions
Staff members of the NSRO for the hospitality