Article
Astronomy & Astrophysics
Xinping Zhou, Yuandeng Shen, Zehao Tang, Chengrui Zhou, Yadan Duan, Song Tan
Summary: This study investigates the driving mechanisms and total reflection effect of a flare-driven quasi-periodic extreme ultraviolet wave train reflected at a coronal hole boundary, using observations from AIA/SDO.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Chaitanya Prasad Sishtla, Jens Pomoell, Rami Vainio, Emilia Kilpua, Simon Good
Summary: Alfvenic fluctuations and CMEs have interactions, including the transmission of solar wind fluctuations to CME sheath and the influence of fluctuation frequencies on the extent of CME sheath.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Beili Ying, Li Feng, Bernd Inhester, Marilena Mierla, Weiqun Gan, Lei Lu, Shuting Li
Summary: This study investigates the formation mechanism of a shock driven by an aspherical CME and demonstrates the impact of the difference in CME's principal radius of curvature on the estimation of shock and coronal parameters. By using three-dimensional reconstructions, the researchers were able to derive corona parameters at high latitudes and analyze the bow-shock formation mechanism.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
K. Martinic, M. Dumbovic, M. Temmer, A. Veronig, B. Vrsnak
Summary: This study investigates different methods for determining the orientation of coronal mass ejections (CMEs) in the near-Sun environment and explores the non-radial flow in the sheath region of interplanetary CMEs (ICMEs). The results show that current methods are limited in accurately determining the orientation of CMEs, but most CMEs have a low inclination. Consistent estimations of the tilt between remote and in situ data were obtained for the majority of CME-ICME pairs. The observed non-radial flows suggest that the CME orientation may impact its propagation.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
N. Yadav, R. Keppens, B. Popescu Braileanu
Summary: Researchers have proposed a new MHD wave decomposition method that overcomes the limitations of existing methods, allowing for the study of energy fluxes associated with different MHD modes in the solar atmosphere. By simulating wave dynamics, they demonstrate that MHD waves excited by ubiquitous vortex flows significantly contribute to the Poynting flux in the solar corona.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
B. Kliem, N. Seehafer
Summary: This study quantitatively confirms the conjecture that magnetic helicity is shed from the Sun by eruptions launching coronal mass ejections, and provides a detailed account of its parametric dependence.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
L. Linan, F. Regnault, B. Perri, M. Brchnelova, B. Kuzma, A. Lani, S. Poedts, B. Schmieder
Summary: This paper aims to use the COCONUT coronal model to compute a detailed representation of a numerical CME at 0.1 AU based on observed magnetograms. By tracking 24 flux ropes with different initial magnetic flux, the shape and properties of the CME during the early stages of propagation were investigated. The results show that the density and magnetic field profiles at 0.1 AU are similar to observations, indicating the presence of a magnetic ejecta composed of the implemented flux rope and a sheath ahead of it. The use of COCONUT in combination with heliospheric simulations could lead to more realistic and reliable CME evolution models and predictions.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Daria Shukhobodskaia, Alexander A. Shukhobodskiy, Robert Erdelyi
Summary: This study explores oscillations in a thin straight expanding magnetic flux tube, finding that cooling increases amplitude and is related to the expansion factor. Higher wave numbers lead to localized oscillations closer to the boundary.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
C. Scolini, S. Dasso, L. Rodriguez, A. N. Zhukov, S. Poedts
Summary: Coronal mass ejections (CMEs) are large-scale eruptions from the Sun into interplanetary space, influencing space weather. The EUropean Heliospheric FORecasting Information Asset (EUHFORIA) model shows consistent descriptions of solar wind and CME radial evolution. However, improvements are necessary for better replication of the CME radial extension.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
G. Mann, A. Warmuth, H. Oenel
Summary: By observing seven class 1 extreme-ultraviolet (EUV) waves in the solar corona, researchers find a relationship between initial velocity and deceleration, which agrees with the theory of large-amplitude magnetohydrodynamic (MHD) waves.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Xinkai Bian, Chaowei Jiang, Xueshang Feng, Pingbing Zuo, Yi Wang, Xinyi Wang
Summary: This study investigates the behavior of the fundamental mechanism behind solar eruption initiation with different photospheric magnetic flux distributions. The research shows that the evolutions of sheared bipolar fields from different magnetograms are consistent with the fundamental mechanism, demonstrating its robustness. It is also found that magnetograms with a stronger polarity inversion line (PIL) produce larger eruptions due to the increased non-potentiality and efficiency of magnetic reconnection. This provides a viable trigger mechanism for observed eruptions in active regions with a strong PIL.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Manon Jarry, Alexis P. Rouillard, Illya Plotnikov, Athanasios Kouloumvakos, Alexander Warmuth
Summary: This study analyzes the geometrical and kinematic properties of coronal and interplanetary shock waves produced by CMEs. The results show the evolution of the shock wave's shape, expansion speeds, and their correlation with the underlying flare activity. These findings contribute to improving space weather forecasting and understanding the eruption process of CMEs.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
E. Chane, B. Schmieder, S. Dasso, C. Verbeke, B. Grison, P. Demoulin, S. Poedts
Summary: The very low densities measured in the solar wind in May 2002 were caused by the over-expansion of a large interplanetary coronal mass ejection (ICME) traveling in the wake of another ICME. This unusual event resulted in a drop of plasma density by two orders of magnitude. This over-expansion was made possible by the low-density and high-velocity environment created by the previous ICME.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
S. Mancuso, A. Bemporad, F. Frassati, D. Barghini, S. Giordano, D. Telloni, C. Taricco
Summary: This study reports the first unambiguous observational evidence of the reflection of a coronal shock wave at the boundary of a coronal hole in the radio range. The research utilizes EUV and radio instruments to track and analyze shock wave phenomena and electron beam acceleration processes in the inner corona.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
D. E. Morosan, J. Pomoell, A. Kumari, E. K. J. Kilpua, R. Vainio
Summary: The Sun produces powerful solar flares and coronal mass ejections (CMEs) which can accelerate electron beams and generate radio bursts. This study investigates the physical mechanism responsible for a type II burst that occurs in the absence of a CME.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Jasa Calogovic, Mateja Dumbovic, Davor Sudar, Bojan Vrsnak, Karmen Martinic, Manuela Temmer, Astrid M. Veronig
Summary: The Drag-Based Model (DBM) is an analytical model used to predict the heliospheric propagation of Coronal Mass Ejections (CMEs) in the solar system, providing accurate calculations of CME arrival time and speed. The Drag-Based Ensemble Model (DBEM) integrates multiple input parameters to calculate the most likely CME arrival times and speeds, quantifying prediction uncertainties.
Article
Astronomy & Astrophysics
Juergen Hinterreiter, Tanja Amerstorfer, Manuela Temmer, Martin A. Reiss, Andreas J. Weiss, Christian Moestl, Luke A. Barnard, Jens Pomoell, Maike Bauer, Ute Amerstorfer
Summary: The study introduces a deformable front model for predicting the arrival time and speed of coronal mass ejections (CMEs) in interplanetary space based on heliospheric imagers (HI) observations. The deformable front model provides more accurate estimates by reacting to ambient solar wind conditions, compared to the original elliptical front model. This new implementation allows for a better understanding of the parameters influencing CME propagation and provides estimates of CME mass.
SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS
(2021)
Review
Astronomy & Astrophysics
Manuela Temmer
Summary: The Sun, as an active star, drives energetic phenomena that impact interplanetary space and planetary atmospheres, with increasing importance on Earth and solar system. New missions and observational capabilities have provided unique perspectives on solar activity phenomena, enhancing our understanding of interplanetary dynamics and Space Weather forecasting models.
LIVING REVIEWS IN SOLAR PHYSICS
(2021)
Article
Astronomy & Astrophysics
Stefan J. Hofmeister, Eleanna Asvestari, Jingnan Guo, Verena Heidrich-Meisner, Stephan G. Heinemann, Jasmina Magdalenic, Stefaan Poedts, Evangelia Samara, Manuela Temmer, Susanne Vennerstrom, Astrid Veronig, Bojan Vrsnak, Robert Wimmer-Schweingruber
Summary: This study investigates the impact of the area of solar coronal holes and the size of their boundary regions on the properties of high-speed solar wind streams near Earth using a simple analytical model. The findings suggest a relationship between the area of coronal holes and the peak velocity of the solar wind streams, as well as changes in temperature and density during their radial expansion from the Sun to Earth.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
A. Wagner, E. Asvestari, M. Temmer, S. G. Heinemann, J. Pomoell
Summary: In this paper, a validation scheme is presented to investigate the quality of coronal magnetic field models by comparing them with observational data. The scheme can assess the reliability and compliance of the models with the observations. It can be applied to any coronal model that produces magnetic field line topology.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
M. Dumbovic, B. Vrsnak, M. Temmer, B. Heber, P. Kuehl
Summary: Researchers observed and analyzed a long-lived CIR, finding a correlation between the decrease in galactic cosmic ray flux and changes in solar wind speed. They also found a relationship between the magnetic field peak and flow speed of the CIR with the amplitude of the cosmic ray count dip. The results suggest that the physical properties of recurring CIRs are similar regardless of their origin from different coronal holes.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
K. Martinic, M. Dumbovic, M. Temmer, A. Veronig, B. Vrsnak
Summary: This study investigates different methods for determining the orientation of coronal mass ejections (CMEs) in the near-Sun environment and explores the non-radial flow in the sheath region of interplanetary CMEs (ICMEs). The results show that current methods are limited in accurately determining the orientation of CMEs, but most CMEs have a low inclination. Consistent estimations of the tilt between remote and in situ data were obtained for the majority of CME-ICME pairs. The observed non-radial flows suggest that the CME orientation may impact its propagation.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
E. Samara, B. Laperre, R. Kieokaew, M. Temmer, C. Verbeke, L. Rodriguez, J. Magdalenic, S. Poedts
Summary: This study introduces dynamic time warping (DTW) as an alternative method for evaluating the performance of models, particularly quantifying the differences between observed and modeled solar wind time series. DTW can warp sequences in time to align them, using dynamic programming. It can evaluate modeled solar wind time series by calculating the sequence similarity factor and quantifying the time and amplitude differences between best matched points.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Florian Koller, Manuela Temmer, Luis Preisser, Ferdinand Plaschke, Paul Geyer, Lan K. Jian, Owen W. Roberts, Heli Hietala, Adrian T. LaMoury
Summary: This study provides a statistical analysis of magnetosheath jets, which are a significant coupling effect between the solar wind and Earth's magnetosphere. The research reveals the variation in the number and duration of jets during different solar wind structures like coronal mass ejections, stream interaction regions, and high-speed streams.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2022)
Article
Astronomy & Astrophysics
M. Temmer, V. Bothmer
Summary: The plasma and magnetic field characteristics of the upstream regions of interplanetary coronal mass ejections (ICMEs) and their evolution as a function of distance to the Sun in the inner heliosphere were investigated. It was found that the sheath structure consists of compressed plasma following the shock and lies ahead of a region of compressed ambient solar wind. The sheath density starts to dominate over the density within the magnetic ejecta (ME) between 0.09 and 0.28 au, and the ME density falls below the ambient solar wind density over 0.45-1.18 au. The size of the sheath shows a weak positive correlation with distance from the Sun.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Bin Zhuang, Noe Lugaz, Manuela Temmer, Tingyu Gou, Nada Al-Haddad
Summary: Magnetic reconnection plays an important role in the early acceleration of coronal mass ejections (CMEs). However, it is still unclear how reconnection contributes to the true acceleration and expansion separately. By analyzing the dynamics of a moderately fast CME, it is found that the apparent acceleration of the CME is due to its expansion in the radial direction, and the true acceleration and radial expansion have similar magnitudes. Magnetic reconnection occurs after the eruption of the CME and continues during its propagation in the high corona, contributing to its dynamic evolution.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Florian Koller, Ferdinand Plaschke, Manuela Temmer, Luis Preisser, Owen W. W. Roberts, Zoltan Voros
Summary: Magnetosheath jets are dynamic pressure enhancements observed in the terrestrial magnetosheath. The generation mechanisms of these jets are currently debated but they can be largely linked to foreshock processes. Recent results showed that the occurrence of jets is affected by the interaction of coronal mass ejections (CMEs) and stream interaction regions (SIRs). This study investigates the relationship between the substructures of CMEs and SIRs and the production of jets.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Rositsa Miteva, Mohamed Nedal, Susan W. Samwel, Manuela Temmer
Summary: In this study, correlations between the intensity of geomagnetic storms (GS) and solar and interplanetary (IP) phenomena parameters were examined. Three-dimensional geometry reconstructions of geo-effective coronal mass ejections (CMEs) were also performed using the PyThea framework, with a focus on the reliability of the de-projection capabilities. Different models for CME reconstruction and observer subjectivity led to large variations in the de-projections of CME speeds. The combination of fast speed and frontal orientation of the magnetic structure upon reaching the terrestrial magnetosphere proved to be the best indicator for GS strength. More accurate estimations of geometry and directivity, as well as de-projected speeds, are crucial for GS forecasting in operational space weather schemes.
Article
Astronomy & Astrophysics
Stephan G. Heinemann, Manuela Temmer, Stefan J. Hofmeister, Aleksandar Stojakovic, Laurent Gizon, Dan Yang
Summary: Global magnetic field models rely on synoptic data, which may introduce uncertainties during times of increased solar activity. This study presents a new method to estimate far-side open flux within coronal holes using STEREO EUV observations, by correlating the photospheric magnetic field with the transition region features. The relationship between strong magnetic elements in the photosphere and the open flux of coronal holes is established, providing insights for estimating open magnetic flux with an uncertainty of 40-60%.
Article
Astronomy & Astrophysics
Mateja Dumbovic, Jasa Calogovic, Karmen Martinic, Bojan Vrsnak, Davor Sudar, Manuela Temmer, Astrid Veronig
Summary: Solar flares are intense and brief solar activities, releasing energy and electromagnetic radiation such as visible light, ultraviolet, and X-rays.
FRONTIERS IN ASTRONOMY AND SPACE SCIENCES
(2021)