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481 results on '"Veronig, Astrid M."'

101. Interaction of a Moreton/EIT wave and a coronal hole

Author

Veronig, Astrid M., Temmer, Manuela, Vrsnak, Bojan, and Thalmann, Julia

Subjects
Astrophysics
Abstract

We report high-cadence H-alpha observations of a distinct Moreton wave observed at Kanzelhoehe Solar Observatory associated with the 3B/X3.8 flare and CME event of 2005 January 17. The Moreton wave can be identified in about 40 H-alpha frames over a period of 7 min. The EIT wave is observed in only one frame but the derived propagation distance is close to that of the simultaneously measured Moreton wave fronts indicating that they are closely associated phenomena. The large angular extent of the Moreton wave allows us to study the wave kinematics in different propagation directions with respect to the location of a polar coronal hole (CH). In particular we find that the wave segment whose propagation direction is perpendicular to the CH boundary (``frontal encounter'') is stopped by the CH which is in accordance with observations reported from EIT waves (Thompson et al. 1998). However, we also find that at a tongue-shaped edge of the coronal hole, where the front orientation is perpendicular to the CH boundary (the wave ``slides along'' the boundary), the wave signatures can be found up to 100 Mm inside the CH. These findings are briefly discussed in the frame of recent modeling results., Comment: 14 pages, 6 figures, accepted for publication in the ApJ

Published
2006
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102. The Solar Activity Monitor Network – SAMNet

Author

Erdélyi Robertus, Korsós Marianna B., Huang Xin, Yang Yong, Pizzey Danielle, Wrathmall Steven A., Hughes Ifan G., Dyer Martin J., Dhillon Vikram S., Belucz Bernadett, Brajša Roman, Chatterjee Piyali, Cheng Xuewu, Deng Yuanyong, Domínguez Santiago Vargas, Joya Raúl, Gömöry Peter, Gyenge Norbert G., Hanslmeier Arnold, Kucera Ales, Kuridze David, Li Faquan, Liu Zhong, Xu Long, Mathioudakis Mihalis, Matthews Sarah, McAteer James R.T., Pevtsov Alexei A., Pötzi Werner, Romano Paolo, Shen Jinhua, Temesváry János, Tlatov Andrey G., Triana Charles, Utz Dominik, Veronig Astrid M., Wang Yuming, Yan Yihua, Zaqarashvili Teimuraz, and Zuccarello Francesca

Subjects
sun-flares-precursors, Meteorology. Climatology, QC851-999
Abstract

The Solar Activity Magnetic Monitor (SAMM) Network (SAMNet) is a future UK-led international network of ground-based solar telescope stations. SAMNet, at its full capacity, will continuously monitor the Sun’s intensity, magnetic, and Doppler velocity fields at multiple heights in the solar atmosphere (from photosphere to upper chromosphere). Each SAMM sentinel will be equipped with a cluster of identical telescopes each with a different magneto-optical filter (MOFs) to take observations in K I, Na D, and Ca I spectral bands. A subset of SAMM stations will have white-light coronagraphs and emission line coronal spectropolarimeters. The objectives of SAMNet are to provide observational data for space weather research and forecast. The goal is to achieve an operationally sufficient lead time of e.g., flare warning of 2–8 h and provide many sought-after continuous synoptic maps (e.g., LoS magnetic and velocity fields, intensity) of the lower solar atmosphere with a spatial resolution limited only by seeing or diffraction limit, and with a cadence of 10 min. The individual SAMM sentinels will be connected to their master HQ hub where data received from all the slave stations will be automatically processed and flare warning issued up to 26 h in advance.

Published
2022
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103. Uninterrupted Tracking of Coronal Mass Ejections

Author

Mason, James Paul, primary, Chamberlin, Phillip C., additional, Dissauer, Karin, additional, Eparvier, Francis, additional, Gibson, Sarah, additional, Gilly, Chris R., additional, Jin, Meng, additional, Jones, Andrew R., additional, Pesnell, W. Dean, additional, Seaton, Daniel B., additional, Veronig, Astrid M., additional, West, Matthew J., additional, and Woods, Thomas N., additional

Published
2023
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107. The Solar Particle Acceleration Radiation and Kinetics (SPARK) Mission Concept

Author

Reid, Hamish A. S., Musset, Sophie, Ryan, Daniel F., Andretta, Vincenzo, Auchère, Frédéric, Baker, Deborah, Benvenuto, Federico, Browning, Philippa, Buchlin, Éric, Calcines Rosario, Ariadna, Christe, Steven D., Corso, Alain Jody, Dahlin, Joel, Dalla, Silvia, Del Zanna, Giulio, Denker, Carsten, Dudík, Jaroslav, Erdélyi, Robertus, Ermolli, Ilaria, Fletcher, Lyndsay, Fludra, Andrzej, Green, Lucie M., Gordovskyy, Mykola, Guglielmino, Salvo L., Hannah, Iain, Harrison, Richard, Hayes, Laura A., Inglis, Andrew R., Jeffrey, Natasha L. S., Kašparová, Jana, Kerr, Graham S., Kintziger, Christian, Kontar, Eduard P., Krucker, Säm, Laitinen, Timo, Laurent, Philippe, Limousin, Olivier, Long, David M., Maloney, Shane A., Massa, Paolo, Massone, Anna Maria, Matthews, Sarah, Mrozek, Tomasz, Nakariakov, Valery M., Parenti, Susanna, Piana, Michele, Polito, Vanessa, Pesce-Rollins, Melissa, Romano, Paolo, Rouillard, Alexis P., Sasso, Clementina, Shih, Albert Y., Stęślicki, Marek, Orozco Suárez, David, Teriaca, Luca, Verma, Meetu, Veronig, Astrid M., Vilmer, Nicole, Vocks, Christian, Warmuth, Alexander, Reid, Hamish A. S., Musset, Sophie, Ryan, Daniel F., Andretta, Vincenzo, Auchère, Frédéric, Baker, Deborah, Benvenuto, Federico, Browning, Philippa, Buchlin, Éric, Calcines Rosario, Ariadna, Christe, Steven D., Corso, Alain Jody, Dahlin, Joel, Dalla, Silvia, Del Zanna, Giulio, Denker, Carsten, Dudík, Jaroslav, Erdélyi, Robertus, Ermolli, Ilaria, Fletcher, Lyndsay, Fludra, Andrzej, Green, Lucie M., Gordovskyy, Mykola, Guglielmino, Salvo L., Hannah, Iain, Harrison, Richard, Hayes, Laura A., Inglis, Andrew R., Jeffrey, Natasha L. S., Kašparová, Jana, Kerr, Graham S., Kintziger, Christian, Kontar, Eduard P., Krucker, Säm, Laitinen, Timo, Laurent, Philippe, Limousin, Olivier, Long, David M., Maloney, Shane A., Massa, Paolo, Massone, Anna Maria, Matthews, Sarah, Mrozek, Tomasz, Nakariakov, Valery M., Parenti, Susanna, Piana, Michele, Polito, Vanessa, Pesce-Rollins, Melissa, Romano, Paolo, Rouillard, Alexis P., Sasso, Clementina, Shih, Albert Y., Stęślicki, Marek, Orozco Suárez, David, Teriaca, Luca, Verma, Meetu, Veronig, Astrid M., Vilmer, Nicole, Vocks, Christian, and Warmuth, Alexander

Abstract

Particle acceleration is a fundamental process arising in many astrophysical objects, including active galactic nuclei, black holes, neutron stars, gamma-ray bursts, accretion disks, solar and stellar coronae, and planetary magnetospheres. Its ubiquity means energetic particles permeate the Universe and influence the conditions for the emergence and continuation of life. In our solar system, the Sun is the most energetic particle accelerator, and its proximity makes it a unique laboratory in which to explore astrophysical particle acceleration. However, despite its importance, the physics underlying solar particle acceleration remain poorly understood. The SPARK mission will reveal new discoveries about particle acceleration through a uniquely powerful and complete combination of γ-ray, X-ray, and EUV imaging and spectroscopy at high spectral, spatial, and temporal resolutions. SPARK’s instruments will provide a step change in observational capability, enabling fundamental breakthroughs in our understanding of solar particle acceleration and the phenomena associated with it, such as the evolution of solar eruptive events. By providing essential diagnostics of the processes that drive the onset and evolution of solar flares and coronal mass ejections, SPARK will elucidate the underlying physics of space weather events that can damage satellites and power grids, disrupt telecommunications and GPS navigation, and endanger astronauts in space. The prediction of such events and the mitigation of their potential impacts are crucial in protecting our terrestrial and space-based infrastructure.

Published
2023

108. SunCET: The Sun Coronal Ejection Tracker Concept

Author

Mason James Paul, Chamberlin Phillip C., Seaton Daniel, Burkepile Joan, Colaninno Robin, Dissauer Karin, Eparvier Francis G., Fan Yuhong, Gibson Sarah, Jones Andrew R., Kay Christina, Kirk Michael, Kohnert Richard, Pesnell W. Dean, Thompson Barbara J., Veronig Astrid M., West Matthew J, Windt David, and Woods Thomas N.

Subjects
euv instrument, coronal mass ejections, high dynamic range, cubesat, Meteorology. Climatology, QC851-999
Abstract

The Sun Coronal Ejection Tracker (SunCET) is an extreme ultraviolet imager and spectrograph instrument concept for tracking coronal mass ejections through the region where they experience the majority of their acceleration: the difficult-to-observe middle corona. It contains a wide field of view (0–4 R⊙) imager and a 1 Å spectral-resolution-irradiance spectrograph spanning 170–340 Å. It leverages new detector technology to read out different areas of the detector with different integration times, resulting in what we call “simultaneous high dynamic range”, as opposed to the traditional high dynamic range camera technique of subsequent full-frame images that are then combined in post-processing. This allows us to image the bright solar disk with short integration time, the middle corona with a long integration time, and the spectra with their own, independent integration time. Thus, SunCET does not require the use of an opaque or filtered occulter. SunCET is also compact – ~15 × 15 × 10 cm in volume – making it an ideal instrument for a CubeSat or a small, complementary addition to a larger mission. Indeed, SunCET is presently in a NASA-funded, competitive Phase A as a CubeSat and has also been proposed to NASA as an instrument onboard a 184 kg Mission of Opportunity.

Published
2021
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110. Identifying the energy release site in a solar microflare with a jet

Author

Battaglia, Andrea Francesco, primary, Wang, Wen, additional, Saqri, Jonas, additional, Podladchikova, Tatiana, additional, Veronig, Astrid M., additional, Collier, Hannah, additional, Dickson, Ewan C. M., additional, Podladchikova, Olena, additional, Monstein, Christian, additional, Warmuth, Alexander, additional, Schuller, Frédéric, additional, Harra, Louise, additional, and Krucker, Säm, additional

Published
2023
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111. Multi-point study of the energy release and impulsive CME dynamics in an eruptive C7 flare

Author

Saqri, Jonas, Veronig, Astrid M., Dickson, Ewan C.M., Podladchikova, Tatiana, Warmuth, Alexander, Xiao, Hualin, Gary, Dale E., Battaglia, Andrea, and Krucker, Säm

Subjects
Sun: flares, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Sun: corona, Sun: coronal mass ejections (CMEs), FOS: Physical sciences, corona, Sun: X-rays, gamma rays [Sun], Astronomy and Astrophysics, Sun: X-rays, gamma rays, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

Context. The energy release in eruptive flares and the kinematics of the associated coronal mass ejections (CMEs) are interlinked and require favorable observing positions as both on-disk and off-limb signatures are necessary to characterize these events. Aims. We combine observations from different vantage points to perform a detailed study of a long duration eruptive C7 class flare that occurred on 17 April 2021 and was partially occulted from Earth view. The dynamics and thermal properties of the flare-related plasma flows, the flaring arcade, and the energy releases and particle acceleration are studied together with the kinematic evolution of the associated CME in order to place this long duration event in context of previous eruptive flare studies. Methods. We use data from the Spectrometer-Telescope for Imaging X-rays (STIX) onboard the Solar Orbiter to analyze the spectral characteristics, timing, and spatial distribution of the flare X-ray emission. Data from the Extreme Ultraviolet Imager (EUVI) onboard the Solar TErrestrial RElations Observatory-Ahead (STEREO-A) spacecraft are used for context images as well as to track the ejected plasma close to the Sun. With Atmospheric Imaging Assembly extreme ultraviolet (EUV) images from the Solar Dynamics Observatory, the flare is observed off-limb and differential emission measure maps are reconstructed. The coronagraphs onboard STEREO-A are used to track the CME out to around 8 R·. Results. The flare showed hard X-ray (HXR) bursts over the duration of an hour in two phases lasting from 16:04 UT to 17:05 UT. During the first phase, a strong increase in emission from hot plasma and impulsive acceleration of the CME was observed. The CME acceleration profile shows a three-part evolution of slow rise, acceleration, and propagation in line with the first STIX HXR burst phase, which is triggered by a rising hot (14 MK) plasmoid. During the CME acceleration phase, we find signatures of ongoing magnetic reconnection behind the erupting structure, in agreement with the standard eruptive flare scenario. The subsequent HXR bursts that occur about 30 min after the primary CME acceleration show a spectral hardening (from δ 7 to δ 4) but do not correspond to further CME acceleration and chromospheric evaporation. Therefore, the CME-flare feedback relationship may only be of significance within the first 25 min. of the event under study, as thereafter the flare and the CME eruption evolve independently of each other., Astronomy & Astrophysics, 672, ISSN:0004-6361, ISSN:1432-0746

Published
2023
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123. Multi-instrument STIX microflare study

Author

Saqri, Jonas, primary, Veronig, Astrid M., additional, Warmuth, Alexander, additional, Dickson, Ewan C. M., additional, Battaglia, Andrea Francesco, additional, Podladchikova, Tatiana, additional, Xiao, Hualin, additional, Battaglia, Marina, additional, Hurford, Gordon J., additional, and Krucker, Säm, additional

Published
2022
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126. Improvements on coronal hole detection in SDO/AIA images using supervised classification

Author

Reiss Martin A., Hofmeister Stefan J., De Visscher Ruben, Temmer Manuela, Veronig Astrid M., Delouille Véronique, Mampaey Benjamin, and Ahammer Helmut

Subjects
Solar wind, Coronal holes, Filament channels, Feature extraction, Supervised Classification, Textural features, Meteorology. Climatology, QC851-999
Abstract

We demonstrate the use of machine learning algorithms in combination with segmentation techniques in order to distinguish coronal holes and filaments in SDO/AIA EUV images of the Sun. Based on two coronal hole detection techniques (intensity-based thresholding, SPoCA), we prepared datasets of manually labeled coronal hole and filament channel regions present on the Sun during the time range 2011–2013. By mapping the extracted regions from EUV observations onto HMI line-of-sight magnetograms we also include their magnetic characteristics. We computed shape measures from the segmented binary maps as well as first order and second order texture statistics from the segmented regions in the EUV images and magnetograms. These attributes were used for data mining investigations to identify the most performant rule to differentiate between coronal holes and filament channels. We applied several classifiers, namely Support Vector Machine (SVM), Linear Support Vector Machine, Decision Tree, and Random Forest, and found that all classification rules achieve good results in general, with linear SVM providing the best performances (with a true skill statistic of ≈ 0.90). Additional information from magnetic field data systematically improves the performance across all four classifiers for the SPoCA detection. Since the calculation is inexpensive in computing time, this approach is well suited for applications on real-time data. This study demonstrates how a machine learning approach may help improve upon an unsupervised feature extraction method.

Published
2015
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127. Geomagnetic storm forecasting from solar coronal holes.

Author

Nitti, Simona, Podladchikova, Tatiana, Hofmeister, Stefan J, Veronig, Astrid M, Verbanac, Giuliana, and Bandić, Mario

Subjects
INTERPLANETARY magnetic fields, GEOMAGNETISM, SOLAR wind, SPACE environment, SOLAR magnetic fields, MAGNETIC storms, MAGNETIC fields, HELIOSEISMOLOGY
Abstract

Coronal holes (CHs) are the source of high-speed streams (HSSs) in the solar wind, whose interaction with the slow solar wind creates corotating interaction regions (CIRs) in the heliosphere. Whenever the CIRs hit the Earth, they can cause geomagnetic storms. We develop a method to predict the strength of CIR/HSS-driven geomagnetic storms directly from solar observations using the CH areas and associated magnetic field polarity. First, we build a data set comprising the properties of CHs on the Sun, the associated HSSs, CIRs, and orientation of the interplanetary magnetic field (IMF) at L1, and the strength of the associated geomagnetic storms by the geomagnetic indices Dst and Kp. Then, we predict the Dst and Kp indices using a Gaussian process model, which accounts for the annual variation of the orientation of Earth's magnetic field axis. We demonstrate that the polarity of the IMF at L1 associated with CIRs is preserved in around 83 per cent of cases when compared to the polarity of their CH sources. Testing our model over the period 2010–2020, we obtained a correlation coefficient between the predicted and observed Dst index of R = 0.63/0.73, and Kp index of R = 0.65/0.67, for HSSs having a polarity towards/away from the Sun. These findings demonstrate the possibility of predicting CIR/HSS-driven geomagnetic storms directly from solar observations and extending the forecasting lead time up to several days, which is relevant for enhancing space weather predictions. [ABSTRACT FROM AUTHOR]

Published
2023
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128. STIX X-ray microflare observations during the Solar Orbiter commissioning phase

Author

Battaglia, Andrea Francesco, primary, Saqri, Jonas, additional, Massa, Paolo, additional, Perracchione, Emma, additional, Dickson, Ewan C. M., additional, Xiao, Hualin, additional, Veronig, Astrid M., additional, Warmuth, Alexander, additional, Battaglia, Marina, additional, Hurford, Gordon J., additional, Meuris, Aline, additional, Limousin, Olivier, additional, Etesi, László, additional, Maloney, Shane A., additional, Schwartz, Richard A., additional, Kuhar, Matej, additional, Schuller, Frederic, additional, Senthamizh Pavai, Valliappan, additional, Musset, Sophie, additional, Ryan, Daniel F., additional, Kleint, Lucia, additional, Piana, Michele, additional, Massone, Anna Maria, additional, Benvenuto, Federico, additional, Sylwester, Janusz, additional, Litwicka, Michalina, additional, Stȩślicki, Marek, additional, Mrozek, Tomasz, additional, Vilmer, Nicole, additional, Fárník, František, additional, Kašparová, Jana, additional, Mann, Gottfried, additional, Gallagher, Peter T., additional, Dennis, Brian R., additional, Csillaghy, André, additional, Benz, Arnold O., additional, and Krucker, Säm, additional

Published
2021
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139. Deriving CME volume and density from remote sensing data

Author

Temmer, Manuela, primary, Holzknecht, Lukas, additional, Dumbovic, Mateja, additional, Vrsnak, Bojan, additional, Sachdeva, Nishtha, additional, Heinemann, Stephan G., additional, Dissauer, Karin, additional, Scolini, Camilla, additional, Asvestari, Eleanna, additional, Veronig, Astrid M., additional, and Hofmeister, Stefan, additional

Published
2021
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150. CME–CME Interactions as Sources of CME Geoeffectiveness: The Formation of the Complex Ejecta and Intense Geomagnetic Storm in 2017 Early September

Author

Scolini, Camilla, primary, Chané, Emmanuel, additional, Temmer, Manuela, additional, Kilpua, Emilia K. J., additional, Dissauer, Karin, additional, Veronig, Astrid M., additional, Palmerio, Erika, additional, Pomoell, Jens, additional, Dumbović, Mateja, additional, Guo, Jingnan, additional, Rodriguez, Luciano, additional, and Poedts, Stefaan, additional

Published
2020
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