Search Publications
On the Nature and Genesis of EUV Waves: A Synthesis of Observations from SOHO, STEREO, SDO, and Hinode (Invited Review)
Vourlidas, Angelos; Patsourakos, Spiros
A major, albeit serendipitous, discovery of the SOlar and Heliospheric Observatory mission was the observation by the Extreme Ultraviolet Telescope (EIT) of large-scale extreme ultraviolet (EUV) intensity fronts propagating over a significant fraction of the Sun's surface. These so-called EIT or EUV waves are associated with eruptive phenomena and…
Computer Vision for the Solar Dynamics Observatory (SDO)
Wiegelmann, T.; Hochedez, J. F.; Raouafi, N. -E. +22 more
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 r…
Nonlinear Force-Free Extrapolation of Emerging Flux with a Global Twist and Serpentine Fine Structures
van Driel-Gesztelyi, L.; Démoulin, P.; Baker, D. +5 more
We study the flux emergence process in NOAA active region 11024, between 29 June and 7 July 2009, by means of multi-wavelength observations and nonlinear force-free extrapolation. The main aim is to extend previous investigations by combining, as much as possible, high spatial resolution observations to test our present understanding of small-scal…
Hinode Flare Catalogue
Masuda, S.; Watanabe, K.; Segawa, T.
We describe a catalogue of solar flares observed by the three instruments (SOT, XRT, EIS) onboard the Hinode satellite. From the launch of the Hinode satellite in September 2006 until late 2011, about 5000 solar flares (larger than A-class in the GOES classification) occurred during the five-year period of Hinode observations, and more than half o…
Magnetic Topology of Active Regions and Coronal Holes: Implications for Coronal Outflows and the Solar Wind
Mandrini, C. H.; van Driel-Gesztelyi, L.; Culhane, J. L. +8 more
During 2 - 18 January 2008 a pair of low-latitude opposite-polarity coronal holes (CHs) were observed on the Sun with two active regions (ARs) and the heliospheric plasma sheet located between them. We use the Hinode/EUV Imaging Spectrometer (EIS) to locate AR-related outflows and measure their velocities. Solar-Terrestrial Relations Observatory (…
Are Solar Active Regions with Major Flares More Fractal, Multifractal, or Turbulent Than Others?
Georgoulis, Manolis K.
Multiple recent investigations of solar magnetic-field measurements have raised claims that the scale-free (fractal) or multiscale (multifractal) parameters inferred from the studied magnetograms may help assess the eruptive potential of solar active regions, or may even help predict major flaring activity stemming from these regions. We investiga…
Granular-Scale Elementary Flux Emergence Episodes in a Solar Active Region
van Driel-Gesztelyi, L.; Bellot Rubio, L. R.; Vargas Domínguez, S.
We analyse data from Hinode spacecraft taken over two 54-minute periods during the emergence of AR 11024. We focus on small-scale portions within the observed solar active region and discover the appearance of very distinctive small-scale and short-lived dark features in Ca II H chromospheric filtergrams and Stokes I images. The features appear in…
Explosive Events: Swirling Transition Region Jets
Curdt, W.; Tian, H.; Kamio, S.
In this paper, we extend our earlier work to provide additional evidence for an alternative scenario to explain the nature of events called `explosive events'. The bidirected, fast Doppler motion of explosive events observed spectroscopically in the transition region emission is classically interpreted as a pair of bidirectional jets moving upward…
Oscillations in Active Region Fan Loops: Observations from EIS/ Hinode and AIA/SDO
Banerjee, D.; Krishna Prasad, S.; Singh, Jagdev
Active region fan loops in AR 11076 were studied, in search of oscillations, using high cadence spectroscopic observations from Extreme-ultraviolet Imaging Spectrometer (EIS) on board Hinode combined with imaging sequences from the Atmospheric Imaging Assembly (AIA) on board Solar Dynamics Observatory (SDO). Spectra from EIS were analyzed in two s…
The Creation of Outflowing Plasma in the Corona at Emerging Flux Regions: Comparing Observations and Simulations
van Driel-Gesztelyi, L.; Harra, L. K.; Hood, A. W. +3 more
In this paper we analyse the flux emergence that occurred in the following polarity area of an active region on 1 - 2 December 2006. Observations have revealed the existence of fast outflows at the edge of the emerging flux region. We have performed 3-D numerical simulations to study the mechanisms responsible for these flows. The results indicate…