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Image Processing Techniques and Feature Recognition in Solar Physics
Aschwanden, Markus J.
This review presents a comprehensive and systematic overview of image-processing techniques that are used in automated feature-detection algorithms applied to solar data: i) image pre-processing procedures, ii) automated detection of spatial features, iii) automated detection and tracking of temporal features (events), and iv) post-processing task…
The Structure and Dynamics of the Upper Chromosphere and Lower Transition Region as Revealed by the Subarcsecond VAULT Observations
Nestoras, I.; Teriaca, L.; Patsourakos, S. +5 more
The Very high Angular resolution ULtraviolet Telescope (VAULT) is a sounding rocket payload built to study the crucial interface between the solar chromosphere and the corona by observing the strongest line in the solar spectrum, the Ly α line at 1216 Å. In two flights, VAULT succeeded in obtaining the first ever subarcsecond ( 0.5\hbox{$^''$} ) i…
A Quantitative Model of Energy Release and Heating by Time-dependent, Localized Reconnection in a Flare with Thermal Loop-top X-ray Source
Qiu, J.; Longcope, D. W.; Des Jardins, A. C. +1 more
We present a quantitative model of the magnetic energy stored and then released through magnetic reconnection for a flare on 26 February 2004. This flare, well observed by RHESSI and TRACE, shows evidence of non-thermal electrons for only a brief, early phase. Throughout the main period of energy release there is a super-hot (T≳30 MK) plasma emitt…
Reconnection of a Kinking Flux Rope Triggering the Ejection of a Microwave and Hard X-ray Source I. Observations and Interpretation
Kliem, B.; Karlický, M.
Imaging microwave observations of an eruptive, partially occulted solar flare on 18 April 2001 suggest that the global structure of the event can be described by the helical kink instability of a twisted magnetic flux rope. This model is suggested by the inverse gamma shape of the source exhibiting crossing legs of a rising flux loop and by eviden…
Outflows at the Edges of an Active Region in a Coronal Hole: A Signature of Active Region Expansion?
van Driel-Gesztelyi, L.; Baker, D.; Murray, M. J. +1 more
Outflows of plasma at the edges of active regions surrounded by quiet Sun are now a common observation with the Hinode satellite. While there is observational evidence to suggest that the outflows are originating in the magnetic field surrounding the active regions, there is no conclusive evidence that reveals how they are driven. Motivated by obs…
Energetic Particle Acceleration and Propagation in Strong CME-Less Flares
Klein, K. -L.; Klassen, A.; Trottet, G.
Flares and coronal mass ejections (CMEs) contribute to the acceleration and propagation of solar energetic particles (SEP) detected in the interplanetary space, but the exact roles of these phenomena are yet to be understood. We examine two types of energetic particle tracers related with 15 CME-less flares that emit bright soft X-ray bursts (GOES…
Solar Polar Fields During Cycles 21 - 23: Correlation with Meridional Flows
Janardhan, P.; Gosain, S.; Bisoi, Susanta K.
We have examined polar magnetic fields for the last three solar cycles, viz. Cycles 21, 22, and 23 using NSO/Kitt Peak synoptic magnetograms. In addition, we have used SOHO/MDI magnetograms to derive the polar fields during Cycle 23. Both Kitt Peak and MDI data at high latitudes (78° - 90°) in both solar hemispheres show a significant drop in the …
The Magnetic Field at the Inner Boundary of the Heliosphere Around Solar Minimum
Hoeksema, J. T.; Zhao, X. P.
STEREO A and B observations of the radial magnetic field between 1 January 2007 and 31 October 2008 show significant evidence that in the heliosphere, the ambient radial magnetic field component with any dynamic effects removed is uniformly distributed. Based on this monopolar nature of the ambient heliospheric field we find that the surface beyon…
Short-Term Solar Flare Prediction Using Predictor Teams
Huang, Xin; Yu, Daren; Wang, Huaning +2 more
A short-term solar flare prediction model is built using predictor teams rather than an individual set of predictors. The information provided by the set of predictors could be redundant. So it is necessary to generate subsets of predictors which can keep the information constant. These subsets are called predictor teams. In the framework of rough…
Background Subtraction for the SECCHI/COR1 Telescope Aboard STEREO
St. Cyr, O. C.; Burkepile, J. T.; Thompson, W. T. +2 more
COR1 is an internally occulted Lyot coronagraph, part of the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) instrument suite aboard the twin Solar Terrestrial Relations Observatory (STEREO) spacecraft. Because the front objective lens is subjected to a full solar flux, the images are dominated by instrumental scattered light …