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
Engineering, Aerospace
Hirdesh Kumar, Brajesh Kumar, S. P. Rajaguru
Summary: In this study, the propagation characteristics of atmospheric gravity waves under different magnetic field configurations in the solar atmosphere were investigated. It was found that magnetic fields have a suppressing and scattering effect on the propagation of gravity waves. These results are consistent with previous numerical simulations, suggesting that gravity waves are suppressed or scattered and reflected back into the lower solar atmosphere in the presence of magnetic fields. The observation of gravity waves is of great importance for understanding solar activity and atmospheric physics processes.
ADVANCES IN SPACE RESEARCH
(2023)
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
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
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
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
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
Multidisciplinary Sciences
Caitlin A. Gilchrist-Millar, David B. Jess, Samuel D. T. Grant, Peter H. Keys, Christian Beck, Shahin Jafarzadeh, Julia M. Riedl, Tom Van Doorsselaere, Basilio Ruiz Cobo
Summary: Observational evidence of magnetohydrodynamic wave activity in solar pores is presented, with energy fluxes decreasing at higher atmospheric heights, suggesting solar pores can efficiently guide wave energy upwards. The study highlights the presence of both body- and surface-mode sausage waves in solar pores.
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
(2021)
Editorial Material
Multidisciplinary Sciences
D. B. Jess, P. H. Keys, M. Stangalini, S. Jafarzadeh
Summary: The Sun's photosphere provides a unique platform for studying, observing, and interpreting waves generated across a wide range of spatial and temporal scales. A focused science team discussed current challenges in wave studies, collaborated to produce 15 independent publications, and explored implications for next-generation observing and computing facilities. This article is part of the Theo Murphy meeting issue 'High-resolution wave dynamics in the lower solar atmosphere'.
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
(2021)
Article
Astronomy & Astrophysics
Ali G. A. Abdelkawy, Abdelrazek M. K. Shaltout
Summary: We used the spectropolarimeter aboard the Hinode satellite to investigate the properties of a positive polarity sunspot in an active region. By analyzing the observed Stokes profiles, we studied the thermal, magnetic field, and plasma flows as a function of the optical depth. Our study focused on the circular polarization and area asymmetry of spectral lines in sunspots. We found a large red-shifted velocity localized with a strong magnetic field, as well as a good fit between the observed and calculated circular polarizations and asymmetries.
ASTROPHYSICS AND SPACE SCIENCE
(2023)
Article
Astronomy & Astrophysics
A. B. Grinon-Marin, A. Pastor Yabar, R. Centeno, H. Socas-Navarro
Summary: This study investigates the long-term evolution and atmospheric parameters of light bridges in sunspots. The research finds that light bridges generally exhibit characteristics between umbra and penumbra, with notable non-magnetic traits. Each light bridge also shows unique behavior within common physical properties. Additionally, as the light bridge cools down, magnetic fields decrease, and there is a change in magnetic and non-magnetic line-of-sight velocities.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Sudip Mandal, Natalie A. Krivova, Robert Cameron, Sami K. Solanki
Summary: This study investigates the organization of spot areas within sunspot groups, finding that the single biggest spot typically occupies a large portion of the group area. The findings imply a scale-invariant emergence pattern and provide observational constraints on the emergence process of solar magnetic field. Extrapolation of the results may have implications for giant unresolved starspot features found in Doppler images of highly active Sun-like stars.
ASTRONOMY & ASTROPHYSICS
(2021)