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Magnetohydrodynamic (MHD) waves have been considered as energy sources for heating the solar chromosphere and the corona. Although MHD waves have been observed in the solar atmosphere, there are a lack of quantitative estimates on the…

Solar and Stellar Astrophysics · Physics 2016-11-01 Ryuichi Kanoh , Toshifumi Shimizu , Shinsuke Imada

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

Solar spicules are the fundamental magnetic structures in the chromosphere and considered to play a key role in channelling the chromosphere and corona. Recently, it was suggested by De Pontieu et al. that there were two types of spicules…

Solar and Stellar Astrophysics · Physics 2012-04-17 Y. Z. Zhang , K. Shibata , J. X. Wang , X. J. Mao , T. Matsumoto , Y. Liu , J. T. Su

Aims. We study the coherency of solar spicules intensity oscillations with increasing height above the solar limb in quiet Sun, active Sun and active region using observations from HINODE/SOT. Existence of coherency up to transition region…

Solar and Stellar Astrophysics · Physics 2015-07-15 E. Tavabi , A. Ajabshirizadeh , A. R. Ahangarzadeh Maralani , S. Zeighami

This paper investigates the conditions for producing rapid variations of solar ener- getic particle (SEP) intensity commonly known as dropouts. In particular, we use numerical model simulations based on solving the focused transport…

Solar and Stellar Astrophysics · Physics 2015-06-19 Y. Wang , G. Qin , M. Zhang , S. Dalla

This work reports a novel plasma wave observation in the near-Sun solar wind: frequency-dispersed ion acoustic waves. Similar waves were previously reported in association with interplanetary shocks or planetary bow shocks, but the waves…

Solar and Stellar Astrophysics · Physics 2024-04-24 David M. Malaspina , Robert E. Ergun , Iver H. Cairns , Benjamin Short , Jaye L. Verniero , Cynthia Cattell , Roberto Livi

Interpreting the Stokes profiles observed in quiet regions of the solar chromosphere is a challenging task. The Stokes Q and U profiles are dominated by the scattering polarisation and the Hanle effect, and these processes can only be…

Solar and Stellar Astrophysics · Physics 2018-11-07 Jan Jurcak , Jiri Stepan , Javier Trujillo Bueno , Michele Bianda

One of the earliest indicators of the importance of shock acceleration of solar energetic particles (SEPs) was the broad spatial extent of the "gradual" SEP events produced as the shock waves, driven by wide, fast coronal mass ejections…

Solar and Stellar Astrophysics · Physics 2022-08-31 Donald V. Reames

We find evidence for the first observation of the parametric decay instability (PDI) in the lower solar atmosphere. Specifically, we find that the power spectrum of density fluctuations near the solar transition region resembles the power…

Solar and Stellar Astrophysics · Physics 2022-07-20 Michael Hahn , Xiangrong Fu , Daniel Wolf Savin

We analyze and interpret SOHO/MDI data on oscillation frequency changes between 1996 and 2004 focusing on differences between activity minimum and maximum of solar cycle 23. We study only the behavior of the centroid frequencies, which…

Astrophysics · Physics 2009-11-10 W. A. Dziembowski , P. R. Goode

Recent in-situ observations and numerical models indicated various types of magnetohydrodynamic (MHD) waves contributing to the solar wind acceleration. Among them is an MHD wave decomposition at distances closer than 50 $R_{\odot}$ using…

Solar and Stellar Astrophysics · Physics 2025-03-19 Shota Chiba , Munehito Shoda , Takeshi Imamura

A model is presented for generation of fast solar wind in coronal holes, relying on heating that is dominated by turbulent dissipation of MHD fluctuations transported upwards in the solar atmosphere. Scale-separated transport equations…

Solar and Stellar Astrophysics · Physics 2015-05-14 A. Verdini , M. Velli , W. H. Matthaeus , S. Oughton , P. Dmitruk

Context. Emission lines formed in the transition region and corona show dominantly redshifts and blueshifts, respectively. Aims. We investigate the Doppler shifts in a 3D radiation MHD model of the quiet Sun and compare these to observed…

Solar and Stellar Astrophysics · Physics 2022-05-11 Yajie Chen , Hardi Peter , Damien Przybylski , Hui Tian , Jiale Zhang

Intermittent magnetohydrodynamical turbulence is most likely at work in the magnetized solar atmosphere. As a result, an array of scaling and multi-scaling image-processing techniques can be used to measure the expected self-organization of…

Astrophysics · Physics 2007-05-23 Manolis K. Georgoulis

Small-scale propagating disturbances (PD) are ubiquitous in the solar corona. Time-Normalised Optical Flow (TNOF) is a method developed for mapping PD velocity fields in time series of Extreme-Ultraviolet (EUV) images. We show PD velocity…

Solar and Stellar Astrophysics · Physics 2026-02-04 Nina Stankovic , Huw Morgan , Marilena Mierla , Nancy Narang , Luciano Rodriguez , David Berghmans

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

Insights into the processes of Solar Energetic Particle (SEP) propagation are essential for understanding how solar eruptions affect the radiation environment of near-Earth space. SEP propagation is influenced by turbulent magnetic fields…

Solar and Stellar Astrophysics · Physics 2018-01-11 T. Laitinen , F. Effenberger , A. Kopp , S. Dalla

Prompted by high resolution observations, I propose an explanation for the 40+ year old problem of structure and energy balance in the solar transition region. The ingredients are simply cross-field diffusion of neutral atoms from cool…

Astrophysics · Physics 2009-11-13 Philip G. Judge

We gave an extensive study for the quasi-periodic perturbations on the time profiles of the line of sight (LOS) magnetic field in 10x10 sub-areas in a solar plage region (corresponds to a facula on the photosphere). The perturbations are…

Solar and Stellar Astrophysics · Physics 2022-04-20 Haisheng Ji , Parida Hashim , Zhenxiang Hong , Zhe Xu , Jinhua Shen , Kaifan Ji , Wenda Cao

We investigate coronal heating and acceleration of the high- and low-speed solar wind in the open field region by dissipation of fast and slow magnetohydrodynamical (MHD) waves through MHD shocks. Linearly polarized \Alfven (fast MHD) waves…

Astrophysics · Physics 2009-11-10 Takeru K. Suzuki