G. D. R. Attrill

Defence Science and Technology Laboratory DSTL, New Sarum, England, United Kingdom

Are you G. D. R. Attrill?

Claim your profile

Publications (43)99.72 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: We present evidence of global coronal wave rotation in EUV data from SOHO/EIT, STEREO/EUVI, and SDO/AIA. The sense of rotation is found to be consistent with the helicity of the source region (clockwise for positive helicity, anticlockwise for negative helicity), with the source regions hosting sigmoidal structures. We also study two coronal wave events observed by SDO/AIA where no clear rotation (or sigmoid) is observed. The selected events show supporting evidence that they all originate with flux rope eruptions. We make comparisons across this set of observations (both with and without clear sigmoidal structures). On examining the magnetic configuration of the source regions, we find that the nonrotation events possess a quadrupolar magnetic configuration. The coronal waves that do show a rotation originate from bipolar source regions.
    The Astrophysical Journal 11/2014; 796(1):55. DOI:10.1088/0004-637X/796/1/55 · 6.28 Impact Factor
  • S. H. Saar, G. D. Attrill
    [Show abstract] [Hide abstract]
    ABSTRACT: We discuss Hinode XRT observations of temporally-related emission enhancements in solar X-ray bright points (XBPs) consistent with excitation by an otherwise unseen wave. In one case, the wave source is unclear (out of the field of view), in the other which we report here, the wave seems to be excited by a flaring/erupting XBP. In this latter case, the wave velocity averaged ˜340 km s-1 in areas of quiet Sun emission, but was reduced by ˜1/3 in areas of higher emission and magnetic flux density. Larger loops were mostly unaffected by the wave's passage, while XBPs could still be excited at distances of 105 km and more from the apparent origin. Small coronal dimming regions (displaying characteristic evolution properties in EUV intensity) are seen next to the flaring XBP, suggesting a small CME may have been associated with the event. We speculate on the origin and properties of these mysterious waves, which may prove useful tools for studying the media through which they travel. These events are inconspicuous, showing low intensity enhancements of only selected small regions, and require high cadence, high spatial resolution data to be detected. Since they are easily overlooked and/or confused with stochastic variability, these waves may be a fairly common, but under-recognized component of the flare/CME phenomenon at small energies and spatial scales. SDO's AIA should be very useful in further study of these waves.
    08/2012;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In Fall 2008 NASA selected a large international consortium to produce a comprehensive automated feature-recognition system for the Solar Dynamics Observatory (SDO). The SDO data that we consider are all of the Atmospheric Imaging Assembly (AIA) images plus surface magnetic-field images from the Helioseismic and Magnetic Imager (HMI). We produce robust, very efficient, professionally coded software modules that can keep up with the SDO data stream and detect, trace, and analyze numerous phenomena, including flares, sigmoids, filaments, coronal dimmings, polarity inversion lines, sunspots, X-ray bright points, active regions, coronal holes, EIT waves, coronal mass ejections (CMEs), coronal oscillations, and jets. We also track the emergence and evolution of magnetic elements down to the smallest detectable features and will provide at least four full-disk, nonlinear, force-free magnetic field extrapolations per day. The detection of CMEs and filaments is accomplished with Solar and Heliospheric Observatory (SOHO)/Large Angle and Spectrometric Coronagraph (LASCO) and ground-based Hα data, respectively. Acompletely new software element is a trainable feature-detection module based on a generalized image-classification algorithm. Such a trainable module can be used to find features that have not yet been discovered (as, for example, sigmoids were in the pre-Yohkoh era). Our codes will produce entries in the Heliophysics Events Knowledgebase (HEK) as well as produce complete catalogs for results that are too numerous for inclusion in the HEK, such as the X-ray bright-point metadata. This will permit users to locate data on individual events as well as carry out statistical studies on large numbers of events, using the interface provided by the Virtual Solar Observatory. The operations concept for our computer vision system is that the data will be analyzed in near real time as soon as they arrive at the SDO Joint Science Operations Center and have undergone basic processing. This will allow the system to produce timely space-weather alerts and to guide the selection and production of quicklook images and movies, in addition to its prime mission of enabling solar science. We briefly describe the complex and unique data-processing pipeline, consisting of the hardware and control software required to handle the SDO data stream and accommodate the computer-vision modules, which has been set up at the Lockheed-Martin Space Astrophysics Laboratory (LMSAL), with an identical copy at the Smithsonian Astrophysical Observatory (SAO). KeywordsInstrumentation and data management–Solar Dynamics Observatory
    Solar Physics 01/2011; 275(1):79-113. DOI:10.1007/s11207-010-9697-y · 3.81 Impact Factor
  • Source
    M. J. Wills-Davey, G. D. R. Attrill
    [Show abstract] [Hide abstract]
    ABSTRACT: We present here a review of observations and the current theories that attempt to explain coronal EIT waves. EIT waves were first observed by SOHO-EIT in 1996. Since then, careful analysis has shown that they are related to various other phenomena, such as: CMEs, coronal dimming regions, Moreton waves, and transverse coronal loop oscillations. Over the years, myriad theories have been proposed to explain EIT waves. Early attempts, while elegant, relied heavily on theories based on pre-coronal observations. More recent work, which tends to consider a larger data pool, has led to two competing theoretical camps: wave vs. non-wave models; in many cases, proposed hypotheses flatly contradict each other. Sifting through these seemingly-incongruous models requires a thorough understanding of the available data, as some observations make certain theories more difficult to justify. However, some questions still do not appear resolvable with current data and will likely require help from the next generation of coronal telescopes.
    Space Science Reviews 12/2010; 149(1):325-353. DOI:10.1007/s11214-009-9612-8 · 5.87 Impact Factor
  • Source
    S. Ma, G. D. R. Attrill, L. Golub, and J. Lin
    [Show abstract] [Hide abstract]
    ABSTRACT: Taking advantage of the two viewpoints of the STEREO spacecraft, we present a statistical study of coronal mass ejections (CMEs) with and without distinct low coronal signatures (LCSs) from 2009 January 1 to August 31. During this period, the lines of sight from STEREO A and B are almost perpendicular and nearly a quarter of the Sun was observed by both. We identified 34 CMEs that originated from around this area and find that (1) about 1 out of 3 CMEs that were studied during 8 months of solar minimum activity are stealth CMEs; a CME is stealth if no distinct LCS (such as coronal dimming, coronal wave, filament eruption, flare, post-eruptive arcade) can be found on the disk. (2) The speeds of the stealth CMEs without LCSs are typically below 300 km s–1. Comparing with the slow CMEs with LCSs, the stealth CMEs did not show any clear differences in their velocity and acceleration evolution. (3) The source regions of the stealth CMEs are usually located in the quiet Sun rather than active regions. Detailed study indicates that more than half of the stealth CMEs in this paper showed some faint change of the coronal structures (likely parts of flux ropes) when they could be observed over the solar limb before or during the CME evolution. Finally, we note that space weather detection systems based on LCSs totally independent of coronagraph data may fail to detect a significant proportion of CMEs.
    The Astrophysical Journal 09/2010; 722(1):289. DOI:10.1088/0004-637X/722/1/289 · 6.28 Impact Factor
  • Source
    Gemma D. R. Attrill, Gemma D. R
    [Show abstract] [Hide abstract]
    ABSTRACT: A new analysis of the 2007 May 19 coronal wave-coronal mass ejection-dimmings event is offered employing base difference extreme-ultraviolet (EUV) images. Previous work analyzing the coronal wave associated with this event concluded strongly in favor of purely an MHD wave interpretation for the expanding bright front. This conclusion was based to a significant extent on the identification of multiple reflections of the coronal wave front. The analysis presented here shows that the previously identified 'reflections' are actually optical illusions and result from a misinterpretation of the running difference EUV data. The results of this new multiwavelength analysis indicate that two coronal wave fronts actually developed during the eruption. This new analysis has implications for our understanding of diffuse coronal waves and questions the validity of the analysis and conclusions reached in previous studies.
    The Astrophysical Journal 07/2010; 718(1):494-501. DOI:10.1088/0004-637X/718/1/494 · 6.28 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We perform a numerical study of the evolution of a Coronal Mass Ejection (CME) and its interaction with the coronal magnetic field based on the May 12, 1997, CME event using a global MagnetoHydroDynamic (MHD) model for the solar corona. The ambient solar wind steady-state solution is driven by photospheric magnetic field data, while the solar eruption is obtained by superimposing an unstable flux rope onto the steady-state solution. During the initial stage of CME expansion, the core flux rope reconnects with the neighboring field, which facilitates lateral expansion of the CME footprint in the low corona. The flux rope field also reconnects with the oppositely orientated overlying magnetic field in the manner of the breakout model. During this stage of the eruption, the simulated CME rotates counter-clockwise to achieve an orientation that is in agreement with the interplanetary flux rope observed at 1 AU. A significant component of the CME that expands into interplanetary space comprises one of the side lobes created mainly as a result of reconnection with the overlying field. Within 3 hours, reconnection effectively modifies the CME connectivity from the initial condition where both footpoints are rooted in the active region to a situation where one footpoint is displaced into the quiet Sun, at a significant distance ($\approx 1R_\odot$) from the original source region. The expansion and rotation due to interaction with the overlying magnetic field stops when the CME reaches the outer edge of the helmet streamer belt, where the field is organized on a global scale. The simulation thus offers a new view of the role reconnection plays in rotating a CME flux rope and transporting its footpoints while preserving its core structure. Comment: Accepted to JGR Space Physics, 15 pages, 8 figures
    Journal of Geophysical Research Atmospheres 06/2010; DOI:10.1029/2010JA015464 · 3.44 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We study two CME events on 13 and 14 December 2006 that were associated with large-scale dimmings. We study the eruptions from pre-event on 11 December through the recovery on 15 December, using a combination of Hinode/EIS, SOHO/EIT, SOHO/MDI, and MLSO Halpha data. The GOES X-class flares obscured the core dimmings, but secondary dimmings developed remote from the active region (AR) in both events. The secondary dimmings are found to be formed by a removal of bright coronal material from loops in the plage region to the East of the AR. Using Hinode/EIS data, we find that the outflows associated with the coronal-dimming regions are highly structured. The concentrated outflows are located at the footpoints of coronal loops (which exist before, and are re-established after, the eruptions), and these are correlated with regions of positive magnetic elements. Comparative study of the Hinode/EIS and SOHO/EIT data shows that the reduction in outflow velocity is consistent with the recovery in intensity of the studied regions. We find that concentrated downflows develop during the recovery phase of the dimmings and are also correlated with the same positive magnetic elements that were previously related to outflows. The local behaviour of the flows in and around the dimming regions following the eruptions is found to be dynamic and complex. Despite the global aspects of these events (widespread dimmings, CMEs, coronal waves) being largely homologous, there are significant local variations and distinct differences between the flows associated with the two events. We find that the secondary dimmings recover primarily by re-establishment of the bright coronal loops (the exact configuration changes between the eruptions, which is reflected by the complexity of the flows).
    Solar Physics 06/2010; 264:119-147. DOI:10.1007/s11207-010-9558-8 · 3.81 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The SDO Feature Finding Team produces robust and very efficient software modules that can keep up with the relentless SDO data stream, and detect, trace, and analyze a large number of phenomena including: flares, sigmoids, filaments, coronal dimmings, polarity inversion lines, sunspots, X-ray bright points, active regions, coronal holes, EIT waves, CME's, coronal oscillations, and jets. In addition we track the emergence and evolution of magnetic elements down to the smallest features that are detectable, and we will also provide at least four full disk nonlinear force-free magnetic field extrapolations per day. During SDO commissioning we will install in the near-real time data pipeline the modules that provide alerts for flares, coronal dimmings, and emerging flux, as well as those that trace filaments, sigmoids, polarity inversion lines, and active regions. We will demonstrate the performance of these modules and illustrate their use for science investigations.
    American Astronomical Society Meeting Abstracts #216; 05/2010
  • Suli Ma, G. D. R. Attrill, L. Golub, J. Lin, M. J. Wills-Davey
    [Show abstract] [Hide abstract]
    ABSTRACT: Taking advantage of the two viewpoints of the STEREO spacecraft, we present a statistical study of CMEs with and without distinct low coronal signatures from January 1st to August 31st, 2009. During this period, the line of sight of STEREO A and that of STEREO B are almost perpendicular and nearly a quarter of the Sun was observed by both. We identified 35 front-side (as viewed from Earth) CMEs, around half of which had no distinct low coronal signature (such as dimming, coronal wave, filament eruption, post-eruptive arcade). Study of the CME kinematics showed that in the COR2 field of view there is no obvious difference between CMEs with and without low coronal signatures. The data from COR1 and EUVI suggest that both kinds of CMEs originate from below 1.4Rsun. We conclude that the region between 1.1-1.4Rsun is very important for understanding the nascent development of CMEs. Detailed study indicates that although there may be no major low coronal signatures for half of the CMEs, there still exist some subtle changes in the low corona before or during the CME appearance. Finally, this work acknowledges that automatic space weather detection systems based on low coronal signatures totally independent of coronagraph data, may fail to detect a significant proportion of CMEs.
  • [Show abstract] [Hide abstract]
    ABSTRACT: The Solar Dynamics Observatory (SDO) represents a new frontier in quantity and quality of solar data. At about 1.5 TB/day, the data will not be easily digestible by solar physicists using the same methods that have been employed for images from previous missions. In order for solar scientists to use the SDO data effectively they need meta-data that will allow them to identify and retrieve data sets that address their particular science questions. We are building a comprehensive computer vision pipeline for SDO, abstracting complete metadata on many of the features and events detectable on the Sun without human intervention. Our project unites more than a dozen individual, existing codes into a systematic tool that can be used by the entire solar community. The feature finding codes will run as part of the SDO Event Detection System (EDS) at the Joint Science Operations Center (JSOC; joint between Stanford and LMSAL). The metadata produced will be stored in the Heliophysics Event Knowledgebase (HEK), which will be accessible on-line for the rest of the world directly or via the Virtual Solar Observatory (VSO) . Solar scientists will be able to use the HEK to select event and feature data to download for science studies.
    38th COSPAR Scientific Assembly; 01/2010
  • Steven H. Saar, G. D. R. Attrill
    [Show abstract] [Hide abstract]
    ABSTRACT: We report on Hinode XRT observations of sequential emission enhancements in solar X-ray bright points (XBPs) consistent with excitation by an (otherwise undetected) wave. In one case, the wave appears to have been excited by a flaring/erupting XBP. The wave velocity averaged about 350 km/s in areas of weak magnetic field and quiet Sun emission, but was reduced by about 1/3 in areas of higher magnetic flux density. Larger loops were mostly unaffected by the wave disturbance, which could still excite XBPs at distances of 4e5 km and more from their apparent starting point. We speculate on the origin and properties of these mystery waves, which may be useful as diagnostics of the medium in which they travel. We suspect these waves may be relatively common, but heretofore under-recognized due to their low level, enhancement selectivity, need for high cadence data, and confusion from stochastic variability. SDO's AIA should aid considerably in further study of this intriguing phenomenon. This work was supported by NASA contract NNM07AB07C to SAO.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The relative importance of different initiation mechanisms for coronal mass ejections (CMEs) on the Sun is uncertain. One possible mechanism is the loss of equilibrium of coronal magnetic flux ropes formed gradually by large-scale surface motions. In this paper, the locations of flux rope ejections in a recently-developed quasi-static global evolution model are compared with observed CME source locations over a 4.5-month period in 1999. Using EUV data, the low-coronal source locations are determined unambiguously for 98 out of 330 CMEs. Despite the incomplete observations, positive correlation (with coefficient up to 0.49) is found between the distributions of observed and simulated ejections, but only when binned into periods of one month or longer. This binning timescale corresponds to the time interval at which magnetogram data are assimilated into the coronal simulations, and the correlation arises primarily from the large-scale surface magnetic field distribution; only a weak dependence is found on the magnetic helicity imparted to the emerging active regions. The simulations are limited in two main ways: they produce fewer ejections, and they do not reproduce the strong clustering of observed CME sources into active regions. Due to this clustering, the horizontal gradient of radial photospheric magnetic field is better correlated with the observed CME source distribution (coefficient 0.67). Our results suggest that, while the gradual formation of magnetic flux ropes over weeks can account for many observed CMEs, especially at higher latitudes, there exists a second class of CMEs (at least half) for which dynamic active region flux emergence on shorter timescales must be the dominant factor. Comment: 27 pages, 7 figures, accepted for publication in ApJ
    The Astrophysical Journal 12/2009; DOI:10.1088/0004-637X/709/2/1238 · 6.28 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: On 2007 December 7, there was an eruption from AR 10977, which also hosted a sigmoid. An EUV Imaging Telescope (EIT) wave associated with this eruption was observed by EUVI on board the Solar Terrestrial Relations Observatory (STEREO). Using EUVI images in the 171 Å and the 195 Å passbands from both STEREO A and B, we study the morphology and kinematics of this EIT wave. In the early stages, images of the EIT wave from the two STEREO spacecrafts differ markedly. We determine that the EUV fronts observed at the very beginning of the eruption likely include some intensity contribution from the associated coronal mass ejection (CME). Additionally, our velocity measurements suggest that the EIT wave front may propagate at nearly constant velocity. Both results offer constraints on current models and understanding of EIT waves.
    The Astrophysical Journal 11/2009; 707(1):503. DOI:10.1088/0004-637X/707/1/503 · 6.28 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We report on observations of the first diffuse coronal wave detected by Hinode/XRT. The event occurred near the west solar limb on 2007 May 23, originating from active region (AR) 10956 and was associated with a coronal mass ejection (CME) and coronal dimmings. The bright emission forming the coronal wave expanded predominantly to the east and south of the AR. We use X-Ray Telescope (XRT) and STEREO Behind (B) data combined with a potential magnetic field extrapolation to derive an understanding of the global magnetic field connectivity. We attribute the brightening to the east of the AR to compression and channeling of the plasma along large-scale loops. The brightening to the south of the AR expands across the quiet Sun, making the southern component a likely candidate for identification as a diffuse coronal wave. We analyze the bright front in STEREO/EUVI (B) 171, 195, and 284 Å images, as well as in XRT data, finding the strongest components to be largely cospatial in all bandpasses. We also exploit the near-limb location of this event by combining STEREO/COR1 and Extreme Ultra-Violet Imaging Telescope (EUVI) data. Using all the data, we derive a full picture of the low-coronal development of the eruption. The COR1 data show that the southernmost outer edge of the CME is progressively displaced southward during the expansion. EUVI data below the COR1 occulting disk show that the CME is significantly distorted in the low corona as a result of the associated filament eruption. The core coronal dimmings map to the core of the CME; the secondary coronal dimmings map to the CME cavity; and the diffuse coronal wave maps to the outermost edge of the expanding CME shell. The analysis of this near-limb event has important implications for understanding earlier eruptions originating from the same AR on 2007 May 16, 19, and 20.
    The Astrophysical Journal 10/2009; 704(2):1296. DOI:10.1088/0004-637X/704/2/1296 · 6.28 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: On 13 February 2009, a coronal wave -- CME -- dimming event was observed in quadrature by the STEREO spacecraft. We analyze this event using a three-dimensional, global magnetohydrodynamic (MHD) model for the solar corona. The numerical simulation is driven and constrained by the observations, and indicates where magnetic reconnection occurs between the expanding CME core and surrounding environment. We focus primarily on the lower corona, extending out to $3R_{\odot}$; this range allows simultaneous comparison with both EUVI and COR1 data. Our simulation produces a diffuse coronal bright front remarkably similar to that observed by STEREO/EUVI at 195 \AA. It is made up of \emph{two} components, and is the result of a combination of both wave and non-wave mechanisms. The CME becomes large-scale quite low ($<$ 200 Mm) in the corona. It is not, however, an inherently large-scale event; rather, the expansion is facilitated by magnetic reconnection between the expanding CME core and the surrounding magnetic environment. In support of this, we also find numerous secondary dimmings, many far from the initial CME source region. Relating such dimmings to reconnecting field lines within the simulation provides further evidence that CME expansion leads to the "opening" of coronal field lines on a global scale. Throughout the CME expansion, the coronal wave maps directly to the CME footprint. Our results suggest that the ongoing debate over the "true" nature of diffuse coronal waves may be mischaracterized. It appears that \emph{both} wave and non-wave models are required to explain the observations and understand the complex nature of these events.
    The Astrophysical Journal 09/2009; 705(1). DOI:10.1088/0004-637X/705/1/587 · 6.28 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Coronal dimmings often develop in the vicinity of erupting magnetic configurations. It has been suggested that they mark the location of the footpoints of ejected flux ropes and, thus, their magnetic flux can be used as a proxy for the ejected flux. If so, this quantity can be compared to the flux in the associated interplanetary magnetic cloud (MC) to find clues about the origin of the ejected flux rope. In the context of this interpretation, we present several events for which we have done a comparative solar-interplanetary analysis. We combine SOHO/Extreme Ultraviolet Imaging Telescope (EIT) data and Michelson Doppler Imager (MDI) magnetic maps to identify and measure the flux in the dimmed regions. We model the associated MCs and compute their magnetic flux using in situ observations. We find that the magnetic fluxes in the dimmings and MCs are compatible in some events; though this is not the case for large-scale and intense eruptions that occur in regions that are not isolated from others. We conclude that, in these particular cases, a fraction of the dimmed regions can be formed by reconnection between the erupting field and the surrounding magnetic structures, via a stepping process that can also explain other CME associated events.
    Proceedings of the International Astronomical Union 09/2009; 257:265-270. DOI:10.1017/S174392130902938X
  • [Show abstract] [Hide abstract]
    ABSTRACT: Using EUVI and COR images from both STEREO A and B, we study the 3-D morphology and dynamics of an EIT wave and its associated CME. Our results imply the following conclusions: first, at the beginning of the eruption, the EIT wave observations are likely effected by projection effects due to the CME itself; second, the EIT wave velocity measurements suggest constant velocity; finally, we find that weak Earth-directed CMEs may be difficult to observe using existing instruments. In such cases, EIT waves can be used to predict CMEs.
  • Meredith Wills-Davey, G. D. R. Attrill, A. Engell
    [Show abstract] [Hide abstract]
    ABSTRACT: The observations of the Atmospheric Imaging Assembly aboard the Solar Dynamics Observatory (SDO-AIA) are expected to be groundbreaking within the field of heliophysics. To properly promote and explain the data produced by AIA, it is important that an innovative EPO effort be put forth. This has led to the development of "The AIA Solar Learning Center'' (SLC), an inquiry-based educational website geared towards teaching about AIA and the Sun in general. The goal of the SLC is to provide K-12 students, teachers, parents, and homeschoolers with information and education about the Sun, primarily through hands-on activity modules that explain different aspects of our nearest star and the methods of observing it. While each module ultimately aims to impart information about the Sun or some related physical process, the activities also range across a host of different disciplines, including geology, chemistry, history, music, and art. In order to make the content applicable and accessible, activities are tailored to multiple difficulty levels, catering to different age groups. There is also a strong push towards facilitating teachers; activities are designed to fulfill specific teaching standards, and a host of additional teaching material is provided, including lesson plans and powerpoint presentations. Ultimately, the SLC aims to make science and the Sun inviting and accessible. The "Meet the Scientists'' page will provide pictures and personal bios of participating scientists. Students will have the opportunity to interactively ask solar-related questions. There is even a host of lighter fare, such as a solar music playlist and links to relevant Facebook pages.
  • [Show abstract] [Hide abstract]
    ABSTRACT: We report observations of the first diffuse coronal wave detected by Hinode/XRT. The event occurred near the West solar limb on 23 May 2007, originating from active region (AR) 10956. The bright emission expanded both to the East and South of the AR. We combine the XRT results with data from STEREO (B) and a potential magnetic field extrapolation to understand the global magnetic field connectivity. We consider that the brightenings seen to the East and South of the source AR are generated by different physical processes, due to the distinct magnetic environments in these regions. We attribute the brightening to the East of the AR to compression and channelling of the plasma along large-scale loops. The brightening to the South of the AR expands across the quiet Sun, making the southern component a likely candidate for a classical diffuse coronal wave. We analyse the bright front in STEREO/EUVI 171, 195 and 284 A images, as well as in XRT data, finding it to be largely co-spatial in all bandpasses. The expansion velocity of the diffuse bright front is 250 (± 85) km/s. We also exploit the near-limb properties of this event by combining STEREO/COR1 and EUVI data to derive a full picture of the low-coronal development of the eruption. The COR1 data show that the southern-most outer edge of the CME is progressively displaced southward. The core coronal dimmings map to the bright core of the CME; the secondary coronal dimmings map to the CME cavity; and the diffuse coronal "wave'' maps to the outermost edge of the expanding CME shell. The analysis of this near-limb event has implications for understanding earlier eruptions originating from the same AR. In particular, we present a new analysis of the 19 May 2007 event. NASA grants NNX09AB11G and NNH07AB97C supported this work.

Publication Stats

839 Citations
99.72 Total Impact Points

Institutions

  • 2014
    • Defence Science and Technology Laboratory DSTL
      New Sarum, England, United Kingdom
  • 2009–2011
    • Harvard-Smithsonian Center for Astrophysics
      Cambridge, Massachusetts, United States
    • University of Dundee
      • Division of Mathematics
      Dundee, Scotland, United Kingdom
  • 2004–2009
    • University College London
      • Department of Space and Climate Physics
      Londinium, England, United Kingdom