184 citations · 780 across the 26 of their papers we have counts for
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Exploring if a coronal dimming event can produce coronal hole-like properties
Adriana De-Sassi, Louise Harra, Krzysztof Barczynski +8
Coronal dimmings, or transient coronal holes, are manifested as a sudden reduction in extreme ultraviolet (EUV) and X-ray emission, often following solar eruptions. We investigate…
Current Helicity in Response to Coronal Mass Ejections
Zheng Sun, Ting Li, Xinkai Bian +3
Coronal mass ejections (CMEs), powerful solar eruptions with massive plasma ejected into the interplanetary space, are caused by the release of the magnetic free enengy stored in c…
The temporal evolution of non-neutralized electric currents and the complexity of solar active regions
I. Kontogiannis, M. K. Georgoulis
We study the evolution of electric currents during the emergence of magnetic flux in the solar photosphere and the differences exhibited between solar active regions of different H…
Spectral Background-Subtracted Activity Maps
Carsten Denker, Meetu Verma, Alexander G. M. Pietrow +2
High-resolution solar spectroscopy provides a wealth of information from photospheric and chromospheric spectral lines. However, the volume of data easily exceeds hundreds of milli…
The characteristics of flare- and CME-productive solar active regions
Ioannis Kontogiannis
Solar flares and coronal mass ejections (CMEs) cause immediate and adverse effects on the interplanetary space and geospace. The deeper understanding of the mechanisms that produce…
Multiple Stokes I inversions to infer magnetic fields in the spectral range around Cr I 5782 Å
C. Kuckein, H. Balthasar, C. Quintero Noda +8
The spectral window, containing Fraunhofer lines formed in the solar photosphere, around the magnetically sensitive Cr I lines at 5780.9, 5781.1, 5781.7, 5783.0, and 5783.8 Å, with…
The Flare Likelihood and Region Eruption Forecasting (FLARECAST) Project: Flare forecasting in the big data & machine learning era
M. K. Georgoulis, D. S. Bloomfield, M. Piana +25
The EU funded the FLARECAST project, that ran from Jan 2015 until Feb 2018. FLARECAST had a R2O focus, and introduced several innovations into the discipline of solar flare forecas…
Classification of High-resolution Solar Hα Spectra using t-distributed Stochastic Neighbor Embedding
Meetu Verma, Gal Matijevič, Carsten Denker +7
The Hα spectral line is a well-studied absorption line revealing properties of the highly structured and dynamic solar chromosphere. Typical features with distinct spectral signatu…
Differential Emission Measure Evolution as a Precursor of Solar Flares
C. Gontikakis, I. Kontogiannis, M. K. Georgoulis +4
We analyse the temporal evolution of the Differential Emission Measure (DEM) of solar active regions and explore its usage in solar flare prediction. The DEM maps are provided by t…
A persistent quiet-Sun small-scale tornado III. Waves
Kostas Tziotziou, Georgia Tsiropoula, Ioannis Kontogiannis
Vortex flows can foster a variety of wave modes. A recent oscillatory analysis of a persistent 1.7 h vortex flow with a significant substructure has suggested the existence of vari…
The Solar Orbiter Science Activity Plan: translating solar and heliospheric physics questions into action
I. Zouganelis, A. De Groof, A. P. Walsh +182
Solar Orbiter is the first space mission observing the solar plasma both in situ and remotely, from a close distance, in and out of the ecliptic. The ultimate goal is to understand…
Observational study of chromospheric heating by acoustic waves
V. Abbasvand, M. Sobotka, M. Švanda +9
Aims. To investigate the role of acoustic and magneto-acoustic waves in heating the solar chromosphere, observations in strong chromospheric lines are analyzed by comparing the dep…
High-resolution spectroscopy of an erupting minifilament and its impact on the nearby chromosphere
I. Kontogiannis, E. Dineva, A. Diercke +4
We study the evolution of a mini-filament eruption in a quiet region at the center of the solar disk and its impact on the ambient atmosphere. We used high-spectral resolution imag…
Magnetic Flux Emergence in a Coronal Hole
J. Palacios, D. Utz, S. Hofmeister +13
A joint campaign of various space-borne and ground-based observatories, comprising the Japanese Hinode mission (HOP~338, 20\,--\,30~September 2017), the GREGOR solar telescope, and…
High-resolution spectroscopy of a surge in an emerging flux region
M. Verma, C. Denker, A. Diercke +6
High-spectral resolution observations using the VTT echelle spectrograph in the chromospheric H line were obtained in the early growth phase of active region NOAA 12722. Noise-s…
Emergence of small-scale magnetic flux in the quiet Sun
I. Kontogiannis, G. Tsiropoula, K. Tziotziou +4
We study the evolution of a small-scale emerging flux region (EFR) in the quiet Sun, from its emergence to its decay. We track processes and phenomena across all atmospheric layers…
Which Photospheric Characteristics are Most Relevant to Active-Region Coronal Mass Ejections?
Ioannis Kontogiannis, Manolis K. Georgoulis, Jordan A. Guerra +2
We investigate the relation between characteristics of coronal mass ejections and parameterizations of the eruptive capability of solar active regions widely used in solar flare pr…
A persistent quiet-Sun small-scale tornado. II. Oscillations
K. Tziotziou, G. Tsiropoula, I. Kontogiannis
Recently, the characteristics, and dynamics of a persistent 1.7 h vortex flow, resembling a small-scale tornado, have been investigated with ground-base and space-based observation…
Testing and Improving a Set of Morphological Predictors of Flaring Activity
Ioannis Kontogiannis, Manolis K. Georgoulis, Sung-Hong Park +1
Efficient prediction of solar flares relies on parameters that quantify the eruptive capability of solar active regions. Several such quantitative predictors have been proposed in…
Probing the quiet solar atmosphere from the photosphere to the corona
Ioannis Kontogiannis, Costis Gontikakis, Georgia Tsiropoula +1
We investigate the morphology and temporal variability of a quiet Sun network region in different solar layers. The emission in several EUV spectral lines through both raster and s…
Forecasting Solar Flares Using Magnetogram-based Predictors and Machine Learning
Kostas Florios, Ioannis Kontogiannis, Sung-Hong Park +4
We propose a forecasting approach for solar flares based on data from Solar Cycle 24, taken by the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (S…
Active Region Photospheric Magnetic Properties Derived from Line-of-sight and Radial Fields
Jordan A. Guerra, Sung-H. Park, Ioannis Kontogiannis +3
The effect of using two representations of the normal-to-surface magnetic field to calculate photospheric measures that are related to active region (AR) potential for flaring is p…
Non-neutralized electric currents in solar active regions and flare productivity
Ioannis Kontogiannis, Manolis K. Georgoulis, Sung-Hong Park +1
We explore the association of non-neutralized currents with solar flare occurrence in a sizable sample of observations, aiming to show the potential of such currents in solar flare…
Wave propagation in a solar quiet region and the influence of the magnetic canopy
Ioannis Kontogiannis, Georgia Tsiropoula, Kostas Tziotziou
Aims. We seek indications or evidence of transmission/conversion of magnetoacoustic waves at the magnetic canopy, as a result of its impact on the properties of the wave field of t…