Search Publications
A Characteristic Magnetic Field Pattern Associated with All Major Solar Flares and Its Use in Flare Forecasting
Schrijver, Carolus J.
Solar flares result from some electromagnetic instability that occurs within regions of relatively strong magnetic field in the Sun's atmosphere. The processes that enable and trigger these flares remain topics of intense study and debate. I analyze observations of 289 X- and M-class flares and over 2500 active region magnetograms to discover (1) …
On the Magnetic Flux Budget in Low-Corona Magnetic Reconnection and Interplanetary Coronal Mass Ejections
Qiu, Jiong; Hu, Qiang; Howard, Timothy A. +1 more
We present the first quantitative comparison between the total magnetic reconnection flux in the low corona in the wake of coronal mass ejections (CMEs) and the magnetic flux in magnetic clouds (MCs) that reach 1 AU 2-3 days after CME onset. The total reconnection flux is measured from flare ribbons, and the MC flux is computed using in situ obser…
Coronal ``Wave'': Magnetic Footprint of a Coronal Mass Ejection?
Harra, Louise K.; Attrill, Gemma D. R.; van Driel-Gesztelyi, Lidia +1 more
We investigate the properties of two ``classical'' EUV Imaging Telescope (EIT) coronal waves. The two source regions of the associated coronal mass ejections (CMEs) possess opposite helicities, and the coronal waves display rotations in opposite senses. We observe deep core dimmings near the flare site and also widespread diffuse dimming, accompan…
Coronal Pseudostreamers
Sheeley, N. R., Jr.; Wang, Y. -M.; Rich, N. B.
In a recent study of the 2006 solar eclipse, we noted that there are two kinds of coronal streamers: ``helmet streamers,'' which separate coronal holes of opposite magnetic polarity, and ``pseudostreamers,'' which overlie twin loop arcades and separate holes of the same polarity. It is well known that the heliospheric plasma and current sheets rep…
A Comparative Study between Eruptive X-Class Flares Associated with Coronal Mass Ejections and Confined X-Class Flares
Wang, Yuming; Zhang, Jie
We examine the two kinds of major energetic phenomena that occur in the solar atmosphere: eruptive and confined events. The former describes flares with associated coronal mass ejections (CMEs), while the latter denotes flares without associated CMEs. We find that about 90% of X-class flares are eruptive, but the remaining 10% are confined. To pro…
Quantitative Forecasting of Major Solar Flares
Rust, David M.; Georgoulis, Manolis K.
We define the effective connected magnetic field, Beff, a single metric of the flaring potential in solar active regions. We calculated Beff for 298 active regions (93 X- and M-flaring, 205 nonflaring) as recorded by SOHO/MDI during a 10 yr period covering much of solar cycle 23. We find that Beff is a robust crite…
Survey of Magnetic Helicity Injection in Regions Producing X-Class Flares
Georgoulis, M. K.; Rust, D. M.; LaBonte, B. J.
Virtually all X-class flares produce a coronal mass ejection (CME), and each CME carries magnetic helicity into the heliosphere. Using magnetograms from the Michelson Doppler Imager on the Solar and Heliospheric Observatory, we surveyed magnetic helicity injection into 48 X-flare-producing active regions recorded by the MDI between 1996 July and 2…
Solar Magnetic Tracking. I. Software Comparison and Recommended Practices
Lamb, D. A.; DeForest, C. E.; Hagenaar, H. J. +2 more
Feature tracking and recognition are increasingly common tools for data analysis, but are typically implemented on an ad hoc basis by individual research groups, limiting the usefulness of derived results when selection effects and algorithmic differences are not controlled. Specific results that are affected include the solar magnetic turnover ti…
A TRACE White Light and RHESSI Hard X-Ray Study of Flare Energetics
Fletcher, L.; Hannah, I. G.; Hudson, H. S. +1 more
In this paper we investigate the formation of the white-light (WL) continuum during solar flares and its relationship to energy deposition by electron beams inferred from hard X-ray emission. We analyze nine flares spanning GOES classifications from C4.8 to M9.1, seven of which show clear cospatial RHESSI hard X-ray and TRACE WL footpoints. We cha…
Are ``EIT Waves'' Fast-Mode MHD Waves?
DeForest, C. E.; Stenflo, J. O.; Wills-Davey, M. J.
We examine the nature of large-scale, coronal, propagating wave fronts (``EIT waves'') and find they are incongruous with solutions using fast-mode MHD plane-wave theory. Specifically, we consider the following properties: nondispersive single pulse manifestations, observed velocities below the local Alfvén speed, and different pulses which travel…