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At intermediate and high degree $l$, solar p- and f modes can be considered as surface waves. Using variational principle, we derive an integral expression for the group velocities of the surface waves in terms of adiabatic eigenfunctions…

Solar and Stellar Astrophysics · Physics 2015-06-18 S. V. Vorontsov , V. A. Baturin , S. V. Ayukov , V. K. Gryaznov

Here we present a proof of concept for the application of the Variance of Laplacian (VL) method in quantifying the sharpness of optical solar images. We conducted a comprehensive study using over 65,000 individual solar images acquired on…

Instrumentation and Methods for Astrophysics · Physics 2024-05-21 Chu Wing So , Edwin Lok Hei Yuen , Edgar Heung Fat Leung , Jason Chun Shing Pun

The propagation direction and true velocity of a solar coronal mass ejection, which are among the most decisive factors for its geo-effectiveness, are difficult to determine through single-perspective imaging observations. Here we show that…

Solar and Stellar Astrophysics · Physics 2022-06-01 Yu Xu , Hui Tian , Zhenyong Hou , Zihao Yang , Yuhang Gao , Xianyong Bai

Studies on the dynamics of solar filaments have significant implications for understanding their formation, evolution, and eruption, which are of great importance for space weather warning and forecasting. The H$\alpha$ Imaging Spectrograph…

Solar and Stellar Astrophysics · Physics 2024-02-23 Z. Zheng , Q. Hao , Y. Qiu , J. Hong , C. Li , M. D. Ding

Correlation filter (CF) based tracking algorithms have demonstrated favorable performance recently. Nevertheless, the top performance trackers always employ complicated optimization methods which constraint their real-time applications. How…

Computer Vision and Pattern Recognition · Computer Science 2019-05-14 Yipeng Ma , Chun Yuan , Peng Gao , Fei Wang

The solar wind, a stream of charged particles originating from the Sun and transcending interplanetary space, poses risks to technology and astronauts. In this work, we develop a prediction model to forecast the solar wind speed at the…

Solar and Stellar Astrophysics · Physics 2025-01-22 Daniel Collin , Yuri Shprits , Stefan J. Hofmeister , Stefano Bianco , Guillermo Gallego

Next-generation ground-based solar observations require good image quality metrics for post-facto processing techniques. Based on the assumption that texture features in solar images are multi-fractal which can be extracted by a trained…

Instrumentation and Methods for Astrophysics · Physics 2019-10-09 Yi Huang , Peng Jia , Dongmei Cai , Bojun Cai

A new approach to estimating the velocity of the pole moving is considered. The method uses the model-calculated spatial distribution of the (vector) horizontal component \textbf{H} for a given year and its change relative to the closest…

Geophysics · Physics 2023-01-18 S. A. Ivanov , S. A. Merkuryev , I. M. Demina

According to time-distance helioseismology, information about internal fluid motions is encoded in the travel times of solar waves. The inverse problem consists of inferring 3-D vector flows from a set of travel-time measurements. Here we…

Solar and Stellar Astrophysics · Physics 2015-05-27 M. Svanda , L. Gizon , S. M. Hanasoge , S. D. Ustyugov

We review (i) observations and numerical simulations of vortical flows in the solar atmosphere and (ii) measurements of the horizontal magnetic field in quiet Sun regions. First, we discuss various manifestations of vortical flows and…

Solar and Stellar Astrophysics · Physics 2012-02-21 O. Steiner , R. Rezaei

Linear time-distance helioseismic inversions are carried out using several filtering schemes to determine vector flow velocities within two $\sim100^2\,{\rm Mm^2}\times 20\,{\rm Mm}$ realistic magnetohydrodynamic sunspot simulations of…

Solar and Stellar Astrophysics · Physics 2015-06-22 K. DeGrave , J. Jackiewicz , M. Rempel

The solar convection manifests as granulation and intergranulation at the solar surface. In the photosphere, convective motions induce differential Doppler shifts to spectral lines. The observed convective blueshift varies across the solar…

Solar and Stellar Astrophysics · Physics 2018-03-14 Johannes Löhner-Böttcher , Wolfgang Schmidt , Franziska Stief , Tilo Steinmetz , Ronald Holzwarth

Searches for exoplanets with radial velocity techniques are increasingly sensitive to stellar activity. It is therefore crucial to characterize how this activity influences radial velocity measurements in their study of the detectability of…

Solar and Stellar Astrophysics · Physics 2015-05-19 Nadège Meunier , Anne-Marie Lagrange , Morgan Desort

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

As a step toward a complete theoretical integration of 3D compressible hydrodynamic simulations into stellar evolution, convection at the surface and sub-surface layers of the Sun is re-examined, from a restricted point of view, in the…

Solar and Stellar Astrophysics · Physics 2014-11-20 W. David Arnett , Casey Meakin , Patrick A. Young

Understanding the global rotational profile of the solar atmosphere and its variation is fundamental to uncovering a comprehensive understanding of the dynamics of the solar magnetic field and the extent of coupling between different layers…

Results of forward modelling of acoustic wave propagation in a realistic solar sub-photosphere with two cases of steady horizontal flows are presented and analysed by the means of local helioseismology. The simulations are based on fully…

Astrophysics · Physics 2009-11-13 S. Shelyag , R. Erdelyi , M. J. Thompson

The technique of normal-mode coupling is a powerful tool with which to seismically image non-axisymmetric phenomena in the Sun. Here we apply mode coupling in the Cartesian approximation to probe steady, near-surface flows in the Sun. Using…

Solar and Stellar Astrophysics · Physics 2022-03-02 Prasad Mani , Chris Hanson , Shravan Hanasoge

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

The volume of data being collected in solar physics has exponentially increased over the past decade and with the introduction of the $\textit{Daniel K. Inouye Solar Telescope}$ (DKIST) we will be entering the age of petabyte solar data.…

Solar and Stellar Astrophysics · Physics 2019-07-10 John A. Armstrong , Lyndsay Fletcher
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