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Related papers: Deep-Focus Diagnostics of Sunspot Structure

200 papers

The Sun's axisymmetric flows, differential rotation and meridional flow, govern the dynamics of the solar magnetic cycle and variety of methods are used to measure these flows, each with its own strengths and weaknesses. Flow measurements…

Solar and Stellar Astrophysics · Physics 2021-09-08 Sushant S. Mahajan , David H. Hathaway , Andrés Muñoz-Jaramillo , Petrus C. Martens

Magnetohydrodynamic interactions between plasma flows and magnetic fields is fundamental to the origin and sustenance of the 11-year sunspot cycle. These processes are intrinsically three-dimensional (3D) in nature. Our goal is to construct…

Solar and Stellar Astrophysics · Physics 2019-03-06 R. Kumar , L. Jouve , D. Nandy

An exospheric kinetic solar wind model is interfaced with an observation-driven single fluid magnetohydrodynamic (MHD) model. Initially, a photospheric magnetogram serves as observational input in the fluid approach to extrapolate the…

Solar and Stellar Astrophysics · Physics 2017-10-04 Sofia-Paraskevi Moschou , Viviane Pierrard , Rony Keppens , Jens Pomoell

Context: The Wilson depression is the difference in geometric height of unit continuum optical depth between the sunspot umbra and the quiet Sun. Measuring the Wilson depression is important for understanding the geometry of sunspots.…

Solar and Stellar Astrophysics · Physics 2018-11-07 B. Löptien , A. Lagg , M. van Noort , S. K. Solanki

Given the current limited knowledge of meteor plasma micro-physics and its interaction with the surrounding atmosphere and ionosphere, meteors are a highly interesting observational target for high-resolution wide-field astronomical…

Earth and Planetary Astrophysics · Physics 2018-01-10 Dino Bektešević , Dejan Vinković , Andrew Rasmussen , Željko Ivezić

Stellar variability strongly impacts the search for low-mass exoplanets with radial velocity techniques. Two types of planet-free time series can be used to quantify this impact: models and direct solar observations after a subtraction of…

Solar and Stellar Astrophysics · Physics 2024-05-20 Nadège Meunier , Anne-Marie Lagrange , Xavier Dumusque , Sophia Sulis

A new time--distance far-side imaging technique was recently developed by utilizing multiple multi-skip acoustic waves. The measurement procedure is applied to 11 years of Doppler observations from the Solar Dynamics Observatory /…

Solar and Stellar Astrophysics · Physics 2022-01-05 Junwei Zhao , Grace Y. Jing , Ruizhu Chen

The 'standard solar' flare model collects all physical ingredients identified by multi-wavelength observations of our Sun: magnetic reconnection, fast particle acceleration and the resulting emission at various wavelengths, especially in…

Solar and Stellar Astrophysics · Physics 2020-06-24 Wenzhi Ruan , Chun Xia , Rony Keppens

Solar flares involve the sudden release of magnetic energy in the solar corona. Accelerated nonthermal electrons have often been invoked as the primary means for transporting the bulk of the released energy to the lower solar atmosphere.…

Solar and Stellar Astrophysics · Physics 2019-02-20 Sijie Yu , Bin Chen

We address the estimation of seismic wavefields by means of Multidimensional Deconvolution (MDD) for various redatuming applications. While offering more accuracy than conventional correlation-based redatuming methods, MDD faces challenges…

Numerical Analysis · Mathematics 2024-04-03 Daria Sushnikova , Matteo Ravasi , David Keyes

Solar prominence models used so far in the analysis of MHD waves in such structures are quite elementary. In this work, we calculate numerically magnetohydrostatic models in two-dimensional configurations under the presence of gravity. Our…

Solar and Stellar Astrophysics · Physics 2015-06-17 J. Terradas , R. Soler , A. J. Díaz , R. Oliver , J. L. Ballester

Local helioseismology has so far relied on semi-analytical methods to compute the spatial sensitivity of wave travel times to perturbations in the solar interior. These methods are cumbersome and lack flexibility. Here we propose a…

Sunspots are known to be strong absorbers of solar oscillation modal power. The most convincing way to demonstrate this is done via Fourier-Hankel decomposition (FHD), where the local oscillation field is separated into in- and outgoing…

Solar and Stellar Astrophysics · Physics 2021-06-04 Matthias Waidele , Markus Roth , Gangadharan Vigeesh , Kolja Glogowski

We present an improved high-index saddle dynamics (iHiSD) for finding saddle points and constructing solution landscapes, which is a crossover dynamics from gradient flow to traditional HiSD such that the Morse theory for gradient flow…

Numerical Analysis · Mathematics 2025-10-22 Hua Su , Haoran Wang , Lei Zhang , Jin Zhao , Xiangcheng Zheng

Maps of the radial magnetic field at a heliocentric distance of ten solar radii are used as boundary conditions in the MHD code CRONOS to simulate a 3D inner-heliospheric solar wind emanating from the rotating Sun out to 1 AU. The input…

Space Physics · Physics 2013-03-19 T. Wiengarten , J. Kleimann , H. Fichtner , R. Cameron , J. Jiang , R. Kissmann , K. Scherer

Global magnetohydrodynamic (MHD) models play an important role in the infrastructure of space weather forecasting. Validating such models commonly utilizes in situ solar wind measurements made near the orbit of the Earth. The purpose of…

Solar and Stellar Astrophysics · Physics 2024-10-31 Chin-Chun Wu , Kan Liou , Brian E. Wood , Y. M. Wang

In a recent paper (Svanda et al., 2008, A&A 477, 285) we pointed out that, based on the tracking of Doppler features in the full-disc MDI Dopplergrams, the active regions display two dynamically different regimes. We speculated that this…

Solar and Stellar Astrophysics · Physics 2015-05-14 Michal Svanda , Mirek Klvana , Michal Sobotka

Magnetic field modifies the properties of waves in a complex way. Significant advances has been made recently in our understanding of the physics of waves in solar active regions with the help of analytical theories, numerical simulations,…

Astrophysics · Physics 2008-12-02 Elena Khomenko

System-scale magnetohydrodynamic (MHD) waves within Earth's magnetosphere are often understood theoretically using box models. While these have been highly instructive in understanding many fundamental features of the various wave modes…

Space Physics · Physics 2022-02-01 M. O. Archer , D. J. Southwood , M. D. Hartinger , L. Rastaetter , A. N. Wright

Mirror modes are ubiquitous in space plasma and grow from pressure anisotropy. Together with other instabilities, they play a fundamental role in constraining the free energy contained in the plasma. This study focuses on mirror modes…