Results 31 to 40 of about 1,066 (184)

Models of the Solar Photosphere [PDF]

Symposium - International Astronomical Union, 1990
This review summarizes the main properties of the available theoretical models of the solar photosphere and the semiempirical models based primarily on observed spectra in different wavelength regions. LTE and non-LTE semiempirical models are compared with LTE and non-LTE theoretical (radiative equilibrium) models calculated with and without convective
openaire   +1 more source

Simulated magnetic flows in the solar photosphere [PDF]

Astronomy & Astrophysics, 2015
Recent Sunrise/IMaX observations have revealed the existence of supersonic magnetic flows. Our aim is to determine the origin of such flows by using realistic MHD simulations. We simulate cancellation and emergence of magnetic flux through the solar photosphere. Our first numerical experiment starts with magnetic field of both polarities.
Danilovic, S., Cameron, R., Solanki, S.
openaire   +3 more sources

Adapted Empirical Modeling of Near‐Sun Solar‐Wind Speeds for Use in Ensemble Forecasts

Space Weather, Volume 24, Issue 9, September 2026.
Abstract Solar wind science and forecasting relies on empirical relations between modeled coronal magnetic‐field structure—particularly flux‐tube expansion and distance to coronal hole boundary—and solar‐wind speed. There is lots of uncertainty in these relations, creating large uncertainties in the inner‐boundary conditions to heliospheric models ...
N. O. Edward‐Inatimi, M. J. Owens, L. Barnard, M. Lang, H. Turner, M. Marsh, S. Gonzi, A. Yeates   +7 more
wiley   +1 more source

The ORCA‐TWIN qCMOS Experiment I. Science Case and Commissioning at Calar Alto Observatory

Astronomische Nachrichten, Volume 347, Issue 7, August 2026.
ABSTRACT We describe a pilot study to explore a new generation of fast and low noise CMOS image sensors for time domain astronomy, using two remote telescopes with a baseline of 1635 km. The experiment involves direct imaging with novel qCMOS image sensor technology that combines fast readout with sub‐electron readout noise.
Martin M. Roth, Paško Roje, Stella Vješnica, Stefan Cikota, Alex J. Brown, Mike Kretlow, Marco Azzaro, Santiago Reinhart, Jesús Aceituno, Harry Dawson, Carsten Denker, Torsten Enßlin, Stephan Geier, Thomas Granzer, Thomas Kupfer, Gianluca Li Causi, Samaya Nissanke, José Luis Ortiz, Fernando Pedichini, Katja Poppenhäger, Axel Schwope   +20 more
wiley   +1 more source

Granular Spots in the Solar Photosphere

The Astrophysical Journal Letters
Granulation and sunspots are fundamental structures of the solar photosphere. Here, we discover the universal dark regions in TiO images from the New Vacuum Solar Telescope and name them granular spots (GSs).
Shaoxuan Tong, Jun Zhang, Zhenyu Jin
doaj   +1 more source

Forecasting Continuum Intensity for Solar Active Region Emergence Prediction Using Transformers

Journal of Geophysical Research: Machine Learning and Computation, Volume 3, Issue 4, August 2026.
Abstract Early and accurate prediction of solar active region (AR) emergence is crucial for space weather forecasting. Building on established Long Short‐Term Memory (LSTM) based approaches for forecasting the continuum intensity decrease associated with AR emergence, this work expands the modeling with new architectures and targets.
Jonas Tirona, Sarang Patil, Spiridon Kasapis, Eren Dogan, John Stefan, Irina N. Kitiashvili, Alexander G. Kosovichev, Mengjia Xu   +7 more
wiley   +1 more source

Identifying Coronal Sources of L1 Solar Wind Disturbances Using the Fisk Heliospheric Magnetic Field and Potential Field Extrapolations during Three Solar Minima

The Astrophysical Journal
The solar minima between solar cycles 22–23, 23–24, and 24–25 are the best observed minima on record. In situ solar wind and interplanetary magnetic field measurements by the Wind and ACE spacecraft at L1 with 1 hr cadence are explored using wavelet ...
P. J. Steyn, D. Johnson, G. J. J. Botha, S. Régnier   +3 more
doaj   +1 more source

Optimization Algorithm for Determining the Source Surface Radius Based on Parker Solar Probe In Situ Measurements From Encounters 1 to 19

Journal of Geophysical Research: Machine Learning and Computation, Volume 3, Issue 4, August 2026.
Abstract The Potential Field Source Surface (PFSS) extrapolation is a method for estimating the large scale coronal magnetic field from photospheric magnetograms. The source surface serves as the outer boundary of its solution domain, and is typically a spherical surface.
Shiouhe Wang, Fang Shen, Yi Yang, Xueshang Feng, Jiansen He   +4 more
wiley   +1 more source

Inferring depth-dependent plasma motions from surface observations using the DeepVel neural network

Journal of Space Weather and Space Climate, 2021
Coverage of plasma motions is limited to the line-of-sight component at the Sun’s surface. Multiple tracking and inversion methods were developed to infer the transverse motions from observational data.
Tremblay Benoit, Cossette Jean-François, Kazachenko Maria D., Charbonneau Paul, Vincent Alain   +4 more
doaj   +1 more source

The UK Met Office’s Coronal Mass Ejection (CME) Ensemble Prediction System

Space Weather, Volume 24, Issue 7, July 2026.
Abstract We describe the 24‐member Coronal Mass Ejection (CME) ensemble prediction system that is used operationally at the UK's Met Office Space Weather Operations Center (MOSWOC) to forecast the arrival time of CMEs at Earth. The ensemble system was built on ad‐hoc assumptions and there is the need to investigate whether the technique can be improved
Siegfried Gonzi, D. R. Jackson, F.‐X. Bocquet, V. J. Pizzo, E. Adamson, G. Millward, A. R. Marble, D. Odstrcil, C. N. Arge   +8 more
wiley   +1 more source