Article
Astronomy & Astrophysics
X. Zhu, T. Wiegelmann
Summary: The aim of this study is to develop a fast and consistent extrapolation method for modeling multiple layers of the solar atmosphere. The new approach combines the magnetohydrostatic extrapolation with the nonlinear force-free field extrapolation, resulting in accurate and efficient reconstruction of the magnetic fields.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
I. O. I. Virtanen, A. A. Pevtsov, L. Bertello, K. Mursula
Summary: This study reconstructs synoptic maps of the photospheric magnetic field from observations of chromospheric plages and the magnetic polarity of sunspots, and uses these maps to investigate the long-term evolution of the Sun's global magnetic fields. The results show a realistic cyclic behavior of the reconstructed active regions, although the polar field strengths in certain cycles may not accurately reflect the evolution of the sunspot number. The modeled coronal structure shows fair agreement with eclipse drawings.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Multidisciplinary Sciences
Ryohko Ishikawa, Javier Trujillo Bueno, Tanausu del Pino Aleman, Takenori J. Okamoto, David E. McKenzie, Frederic Auchere, Ryouhei Kano, Donguk Song, Masaki Yoshida, Laurel A. Rachmeler, Ken Kobayashi, Hirohisa Hara, Masahito Kubo, Noriyuki Narukage, Taro Sakao, Toshifumi Shimizu, Yoshinori Suematsu, Christian Bethge, Bart De Pontieu, Alberto Sainz Dalda, Genevieve D. Vigil, Amy Winebarger, Ernest Alsina Ballester, Luca Belluzzi, Jiri Stepan, Andres Asensio Ramos, Mats Carlsson, Jorrit Leenaarts
Summary: Unprecedented spectropolarimetric observations of an active region plage and its surrounding enhanced network reveal the role of magnetic field in coupling different atmospheric layers and heating the plage chromosphere.
Article
Astronomy & Astrophysics
Zihan Yu, Jie Chen, Jihong Liu, Alexei A. Pevtsov, Ziyao Hu, Zhike Xue, Jiangtao Su, Yuanyong Deng
Summary: We conducted a statistical study on trans-equatorial loops (TLs) from December 2006 to 2020. Our findings reveal that 160 TLs were identified during this period, with 12% of all active regions being connected by TLs. It was observed that 74% of TLs are connected to regions of preceding magnetic polarity (PTLs), while only 26% are connected to regions of following magnetic polarity (FTLs), which can be attributed to Joy's law. The average length of TLs is 20 degrees, and their lengths decrease during the solar cycle. Furthermore, 88% of the TLs appeared near the solar maximum (2014 ± 2) based on a comparison with the smoothed monthly mean number of sunspots from 2009 to 2018. We also found that TLs are more likely to form when sunspots are closer to the equator, and the tilt angle and latitudinal asymmetry of TL foot-points are independent of the solar cycle.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
I. O. I. Virtanen, A. A. Pevtsov, I. I. Virtanen, K. Mursula
Summary: Researchers constructed additional active regions and applied them to the far-side of the Sun in an SFT simulation to assess the possible effects and the magnitude of error that the missing far-side flux causes. The results showed that adding active regions with short lifetimes to the far-side of the Sun results in significantly stronger polar fields in minimum times and slightly delayed polarity reversals.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Rohan E. Louis, Avijeet Prasad, Christian Beck, Debi P. Choudhary, Mehmet S. Yalim
Summary: By studying the solar chromosphere in a sunspot light bridge, it was found that strong electric currents can lead to temperature excess and thermal enhancements in the chromosphere. The thermal effects are primarily concentrated in the height range of 0.4-0.7 Mm above the light bridge.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
I. Tahtinen, I. I. Virtanen, A. A. Pevtsov, K. Mursula
Summary: By studying the relationship between photospheric magnetic fields and ultraviolet radiation, we found that the percentage of bright pixels can explain the variability of 1600 angstrom emission. We developed a model to predict the size of the photospheric magnetic field and found a close correspondence between the magnetic field and bright and dark clusters.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Xianyong Bai, Hui Liu, Yuanyong Deng, Jie Jiang, Jingjing Guo, Yi Bi, Tao Feng, Zhenyu Jin, Wenda Cao, Jiangtao Su, Kaifan Ji
Summary: This study proposes a new method to estimate the magnetic field components from photospheric continuum images using deep convolutional neural networks. Experimental results show that the method can successfully estimate the magnetic field in different regions of the Sun, providing quick and accurate magnetic field information.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
G. J. M. Vissers, S. Danilovic, X. Zhu, J. Leenaarts, C. J. Diaz Baso, J. M. da Silva Santos, J. de la Cruz Rodriguez, T. Wiegelmann
Summary: This study compares the similarity between the chromospheric magnetic field inferred from observations and the field obtained from a magnetohydrostatic extrapolation based on a high-resolution photospheric magnetogram. The results show that the extrapolated field underestimates the amount of structure and the strength of the transverse field.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
E. R. Priest, P. Syntelis
Summary: The recent discovery of greater magnetic flux cancellation at the photosphere has led to the theory of magnetic reconnection being driven by flux cancellation as the cause of various dynamic phenomena, including jets and solar atmospheric heating.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
H. Ebadi, S. Shahmorad, S. Vasheghani Farahani
Summary: The research aims to model torsional waves in twisted flux tubes of solar coronal magnetic plasma structures, using force-free conditions to determine equilibrium magnetic fields and study the effects of magnetic twist parameter on torsional waves. Through numerical calculations and variable separation techniques, magnetic field characteristics and frequency dependence of torsional waves are obtained, revealing an increase in the omega(2)/omega(1) ratio with the twist parameter at a fixed distance.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
E. Liokati, A. Nindos, M. K. Georgoulis
Summary: In this study, the role of magnetic helicity and free magnetic energy in the initiation of eruptions in two differently evolving solar active regions (ARs) was investigated. It was found that both ARs exhibited substantial budgets of free magnetic energy and both positive and negative helicity. The eruptions occurred at times of net helicity peaks that were co-temporal with peaks in the free magnetic energy. These results suggest that differently evolving ARs can produce major eruptive flares even without a strong dominance of one handedness over the other.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
E. Liokati, A. Nindos, Y. Liu
Summary: This study investigates the role of magnetic helicity and magnetic energy accumulation in the generation of coronal mass ejections (CMEs) from emerging solar active regions (ARs). The results show that ARs with larger budgets of magnetic helicity and energy are more likely to produce CMEs, although there are some exceptions. Therefore, in studying the eruptive potential of ARs, both magnetic helicity and energy should be considered.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
A. Prasad, S. Kumar, A. C. Sterling, R. L. Moore, G. Aulanier, R. Bhattacharyya, Q. Hu
Summary: In this study, a magnetohydrodynamic simulation of active region NOAA 12241 was performed to understand the formation and evolution of a magnetic flux rope during the onset of an M6.9 flare. The simulation supports the development of the magnetic flux rope through tether-cutting magnetic reconnection inside the sheared coronal arcade. The eruptive nature of the magnetic flux rope is attributed to its formation in a torus-unstable region and runaway tether-cutting reconnection.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
R. J. Campbell, M. Mathioudakis, M. Collados, P. H. Keys, A. Asensio Ramos, C. J. Nelson, D. Kuridze, A. Reid
Summary: The study reveals the presence of ubiquitous small-scale transverse magnetic fields in the quiet Sun internetwork region, which exhibit complex structures. High-resolution observations and magnetic inversion techniques can be used to characterize and track the dynamic evolution of these small-scale magnetic features.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Gordon Petrie, Alexei Pevtsov, Andrew Schwarz, Marc DeRosa
Review
Astronomy & Astrophysics
P. MacNeice, L. K. Jian, S. K. Antiochos, C. N. Arge, C. D. Bussy-Virat, M. L. DeRosa, B. V. Jackson, J. A. Linker, Z. Mikic, M. J. Owens, A. J. Ridley, P. Riley, N. Savani, I. Sokolov
SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS
(2018)
Article
Astronomy & Astrophysics
M. C. M. Cheung, M. Rempel, G. Chintzoglou, F. Chen, P. Testa, J. Martinez-Sykora, A. Sainz Dalda, M. L. DeRosa, A. Malanushenko, V Hansteen, B. De Pontieu, M. Carlsson, B. Gudiksen, S. W. McIntosh
Article
Astronomy & Astrophysics
Xudong Sun, Tibor Torok, Marc L. DeRosa
Summary: The study explores the difference between solar and stellar coronal mass ejections (CMEs), suggesting that the torus instability of magnetic flux ropes is a key driving mechanism in solar CMEs. The lack of stellar CME detection may be due to the suppression of torus instability. Using the solar magnetic field as a template, the researchers estimate the vertical extent of the 'torus-stable zone' above a stellar active region.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Meng Jin, Mark C. M. Cheung, Marc L. DeRosa, Nariaki Nitta, Carolus J. Schrijver
Summary: This study investigates solar coronal dimmings using a combination of simulation and observation. By simulating different coronal mass ejections (CMEs) and flux rope configurations, and comparing with observational data, the study explores the relationship between coronal dimmings and CME properties. The results suggest that coronal dimmings encode important information about associated CMEs.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
S. A. Gilchrist, K. D. Leka, G. Barnes, M. S. Wheatland, M. L. DeRosa
ASTROPHYSICAL JOURNAL
(2020)
Article
Astronomy & Astrophysics
George H. Fisher, Maria D. Kazachenko, Brian T. Welsch, Xudong Sun, Erkka Lumme, David J. Bercik, Marc L. DeRosa, Mark C. M. Cheung
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES
(2020)
Article
Astronomy & Astrophysics
Carolus J. Schrijver
ASTROPHYSICAL JOURNAL
(2020)
Article
Astronomy & Astrophysics
Alison O. Farrish, David Alexander, Mei Maruo, Marc DeRosa, Frank Toffoletto, Anthony M. Sciola
ASTROPHYSICAL JOURNAL
(2019)
Article
Astronomy & Astrophysics
Marc L. DeRosa, Graham Barnes
ASTROPHYSICAL JOURNAL
(2018)
Article
Astronomy & Astrophysics
Sarah E. Gibson, Kevin Dalmasse, Laurel A. Rachmeler, Marc L. De Rosa, Steven Tomczyk, Giuliana de Toma, Joan Burkepile, Michael Galloy
ASTROPHYSICAL JOURNAL LETTERS
(2017)
Article
Astronomy & Astrophysics
Shin Toriumi, Vladimir S. Airapetian, Hugh S. Hudson, Carolus J. Schrijver, Mark C. M. Cheung, Marc L. DeRosa
ASTROPHYSICAL JOURNAL
(2020)
Article
Astronomy & Astrophysics
J. Todd Hoeksema, William P. Abbett, David J. Bercik, Mark C. M. Cheung, Marc L. DeRosa, George H. Fisher, Keiji Hayashi, Maria D. Kazachenko, Yang Liu, Erkka Lumme, Benjamin J. Lynch, Xudong Sun, Brian T. Welsch
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES
(2020)
