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Astronomy & Astrophysics
I. Poljancic Beljan, R. Jurdana-Sepic, T. Jurkic, R. Brajsa, I. Skokic, D. Sudar, D. Ruzdjak, D. Hrzina, W. Poetzi, A. Hanslmeier, A. M. Veronig
Summary: This study examines the relationship between solar differential rotation and activity, revealing patterns of variation in different phases of the solar cycle and comparing these findings with previous theoretical studies.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Michal Sobotka, Klaus G. Puschmann
Summary: High-resolution observations of horizontal motions in sunspot penumbra have revealed different speeds and directions of granular movements in different regions, shedding light on the structure and evolution of penumbrae.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
J. S. Castellanos Duran, A. Lagg, S. K. Solanki
Summary: Counter Evershed flows (CEFs) are a common feature in active regions (ARs), occurring in 83.5% of ARs regardless of magnetic complexity, but are observed on average for only 5.9% of the total observation time. The lifetime of CEFs follows a log-normal distribution with a median value of 10.6 hours.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Yury A. Nagovitsyn, Aleksandra A. Osipova, Alexei A. Pevtsov
Summary: The study revealed that the tilt angles of solar active regions exhibit non-linear changes with latitude, with significant differences between large long-living groups and small short-living groups. This implies potential differences in the physical properties and formation mechanisms of the two populations of solar groups.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Yury A. Nagovitsyn, Aleksandra A. Osipova
Summary: The aim of this work is to establish a long (410-yr) series of average annual total sunspot areas and analyze the relationship and periodicity between different sunspot indices for reconstruction.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
A. Prasad, M. Ranganathan, C. Beck, D. P. Choudhary, Q. Hu
Summary: The study found that the inverse Evershed flow is driven along magnetic field lines connecting network elements with the outer penumbra, due to a gas pressure difference resulting from a difference in field strength. The gas pressure difference dominating the pressure force towards the inner foot points is primarily influenced by the difference in field strength.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
H. Strecker, N. Bello Gonzalez
Summary: This study investigates the evolution of the flow field around sunspots and identifies two different scenarios for the evolution of the flow region surrounding a spot in the final stage of its decay. Observational evidence supports theoretical predictions, and the final fate of a spot cell depends on its interaction with the surrounding supergranular cells.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Jihong Liu, Yu Liu, Yin Zhang, Jin Huang, HongQi Zhang
Summary: Using data from the Solar Dynamics Observatory, we studied the signs of helicity and tilt angle in active regions on the Sun. We found that most of the sample regions followed the helicity hemispherical sign rule and there was no significant relationship between helicity and tilt angle. The preference for hemispherical sign and tilt angle was more pronounced in high latitude regions.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
B. Loeptien, A. Lagg, M. van Noort, S. K. Solanki
Summary: The study compared the physical properties of convective features in the umbra and penumbra of sunspots, finding strong similarities between the outer umbra and the penumbra. There is no significant difference in the number density of convective elements between the inner penumbra and the outer umbra.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
J. I. Campos Rozo, S. Vargas Dominguez, D. Utz, A. M. Veronig, A. Hanslmeier
Summary: This study investigates the properties of magnetic fields on the boundaries of solar pores and their time evolution. The results provide important insights into the understanding of the magnetic field properties of the Sun and can contribute to improving models of solar dynamics and magnetic flux emergence.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
M. Murabito, S. L. Guglielmino, I Ermolli, P. Romano, S. Jafarzadeh, L. H. M. Rouppe van der Voort
Summary: The study found that the penumbra disappeared progressively in time and space, with the evolution of magnetic flux seeming to be linked to the presence of moving magnetic features (MMFs). Decreasing Stokes V signals were observed, and Evershed flows and horizontal fields were detected even after the disappearance of the penumbral sector.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
M. Garcia-Rivas, J. Jurcak, N. Bello Gonzalez
Summary: The study reveals the existence of a critical value of the vertical magnetic field on the pore boundary and its significant role in the evolution of the magnetic structure. The stability of pore regions is closely related to the intensity of the vertical magnetic field, similar to the case of stable umbral boundaries in sunspots.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Zhe Xu, Haisheng Ji, Junchao Hong, Kaifan Ji, Jiayan Yang
Summary: In this study, the evolution of the magnetic field and plasma velocity around a fast-moving solar pore was investigated. It was found that pure horizontal magnetic fields are generated in front of the pore, which are highly correlated with the expanding horizontal plasma motions.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
C. Baumgartner, A. C. Birch, H. Schunker, R. H. Cameron, L. Gizon
Summary: The twist of the magnetic field above a sunspot is an important quantity in solar physics, but the sensitivity of the twist proxies to temporal fluctuations has not been well characterized. In this study, a model of a sunspot was used to determine the robustness of different proxies to temporal fluctuations. The results showed that several proxies for the twist of the magnetic field are not biased in each of the individual magnetograms.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Takafumi Kaneko, Hideyuki Hotta, Shin Toriumi, Kanya Kusano
Summary: This study aims to reveal the impact of convective flows on the formation and evolution of sunspot magnetic fields. By simulating the emergence and transport of magnetic flux tubes, it was found that different convective flows can reproduce different types of magnetic distributions. The formation and evolution of delta-spots are related to convective flows and magnetic twist.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)