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The Sun's polar magnetic fields are directly related to solar cycle variability. The strength of the polar fields at the start (minimum) of a cycle determine the subsequent amplitude of that cycle. In addition, the polar field reversals at…

Solar and Stellar Astrophysics · Physics 2014-08-01 Lisa Upton , David H. Hathaway

The sunspot penumbra comprises numerous thin, radially elongated filaments that are central for heat transport within the penumbra, but whose structure is still not clear. To investigate the fine-scale structure of these filaments, we…

Solar and Stellar Astrophysics · Physics 2015-06-16 Sanjiv Kumar Tiwari , Michiel van Noort , Andreas Lagg , Sami K. Solanki

Polarization observations of the Milky Way and many other spiral galaxies have found a close correspondence between the orientation of spiral arms and magnetic field lines on scales of hundreds of parsecs. This paper presents polarization…

Bright points (BPs) in the solar photosphere are radiative signatures of magnetic elements described by slender flux tubes located in the darker intergranular lanes. They contribute to the ultraviolet (UV) flux variations over the solar…

Solar and Stellar Astrophysics · Physics 2016-08-11 T. L. Riethmüller , S. K. Solanki , S. V. Berdyugina , M. Schüssler , V. Martínez Pillet , A. Feller , A. Gandorfer , J. Hirzberger

The Sun and stars with low magnetic activity levels, become photometrically brighter when their activity increases. Magnetically more active stars display the opposite behaviour and get fainter when their activity increases. We reproduce…

Solar and Stellar Astrophysics · Physics 2015-06-19 A. I. Shapiro , S. K. Solanki , N. A. Krivova , W. K. Schmutz , W. T. Ball , R. Knaack , E. V. Rozanov , Y. C. Unruh

Studies of the three-dimensional (3D) structures of galactic magnetic fields are now entering a new era, with broadband, highly sensitive radio observations and new analysis methods. To reveal the magnetic field configuration from the…

Astrophysics of Galaxies · Physics 2023-03-07 Yuta Tashima , Takumi Ohmura , Mami Machida

The main small-scale elements observed in the solar photosphere at high resolution are discussed: granules, faculaes, micropores. As a separate element of the fine structure, a continuous network of dark intergranular gaps is considered.…

Solar and Stellar Astrophysics · Physics 2019-11-07 A. A. Soloviev , L. D. Parfinenko , V. I. Efremov , E. A. Kirichek , O. A. Korolkova

Observations of the Sun in the visible spectral range belong to standard measurements obtained by instruments both on the ground and in the space. Nowadays, both nearly continuous full-disc observations with medium resolution and dedicated…

Solar and Stellar Astrophysics · Physics 2020-06-30 Michal Švanda , Jan Jurčák , David Korda , Jana Kašparová

We present Hubble Space Telescope Near-Infrared Camera and Multi-Object Spectrometer coronagraphic imaging polarimetry of the TW Hydrae protoplanetary disk. These observations simultaneously measure the total and polarized intensity,…

We use the first publically available data from the Daniel K. Inouye Solar Telescope (DKIST) to track magnetic connections from the solar photosphere into the corona. We scrutinize relationships between chromospheric magnetism and bright…

Solar and Stellar Astrophysics · Physics 2023-11-03 Philip Judge , Lucia Kleint , Roberto Casini , Alfred de Wijn , Tom Schad , Alexandra Tritschler

Macrospicules are relatively large spicule-like formations found mainly over the polar coronal holes when observing in the transition region spectral lines. In this study, we took advantage of the two short series of observations in the He…

Solar and Stellar Astrophysics · Physics 2017-01-04 I. P. Loboda , S. A. Bogachev

The distribution and evolution of the magnetic field at the solar poles through a solar cycle is an important parameter in understanding the solar dynamo. The accurate observations of the polar magnetic flux is very challenging from the…

Solar and Stellar Astrophysics · Physics 2024-07-26 Sanjay Gosain , Han Uitenbroek

Observational astrophysics started when spectroscopy could be applied to astronomy. Similarly, observational work on stellar magnetic fields became possible with the application of spectro-polarimetry. In recent decades there have been…

Solar and Stellar Astrophysics · Physics 2015-06-17 J. O. Stenflo

Finding low-mass planets around solar-type stars requires to understand the physical variability of the host star, which greatly exceeds the planet-induced radial-velocity modulation. Different solar photospheric absorption lines have…

Solar and Stellar Astrophysics · Physics 2026-04-16 Dainis Dravins , Hans-Günter Ludwig , Matthias Steffen , Carlos Allende Prieto , Lars Koesterke

Spicules are thin, elongated jet-like features seen in observations of the solar atmosphere, at the interface between the solar photosphere and the corona. These features exhibit highly complex dynamics and are a necessary connecting link…

Solar and Stellar Astrophysics · Physics 2025-08-04 Sankalp Srivastava , Piyali Chatterjee , Sahel Dey , Robertus Erdélyi

Observations of the Sun from the Earth are always limited by the presence of the atmosphere, which strongly disturbs the images. A solution to this problem is to place the telescopes in space satellites, which produce observations without…

Solar and Stellar Astrophysics · Physics 2015-06-24 C. Quintero Noda , A. Asensio Ramos , D. Orozco Suárez , B. Ruiz Cobo

The 3D structure of sunspots has been extensively studied for the last two decades. A recent advancement of the Stokes inversion technique prompts us to revisit the problem. We investigate the global depth-dependent thermal, velocity and…

Solar and Stellar Astrophysics · Physics 2015-11-19 Sanjiv K. Tiwari , Michiel van Noort , Sami K. Solanki , Andreas Lagg

Plages are small concentrations of strong, nearly vertical magnetic fields in the solar photosphere that expand with height. A high spatial and spectral resolution that can resolve their fine structure is required to characterize them, and…

Solar and Stellar Astrophysics · Physics 2025-05-13 G. Liu , I. Milić , J. S. Castellanos Duran , J. M. Borrero , M. van Noort , C. Kuckein

We present observations of planetary nebulae with the LOw Frequency ARray (LOFAR) between 120 and 168 MHz. The images show thermal free-free emission from the nebular shells. We have determined the electron temperatures for spatially…

Plumes are one of the most ubiquitous features seen at the limb in polar coronal holes and are considered to be a source of high density plasma streams to the fast solar wind. We analyze STEREO observations of plumes and aim to reinterpret…

Solar and Stellar Astrophysics · Physics 2010-08-31 Scott W. McIntosh , Davina E. Innes , Bart De Pontieu , Robert J. Leamon
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