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Through its magnetic activity, the Sun governs the conditions in Earth's vicinity, creating space weather events, which have drastic effects on our space- and ground-based technology. One of the most important solar magnetic features…

Solar and Stellar Astrophysics · Physics 2022-05-18 Fadil Inceoglu , Yuri Y. Shprits , Stephan G. Heinemann , Stefano Bianco

We present a study of three highly non-radial solar wind events when the azimuthal solar wind flow angle exceeds > 6 degrees for one day or more. None of the events are associated with coronal mass ejections and co-rotating interaction…

Solar and Stellar Astrophysics · Physics 2024-01-22 Susanta Kumar Bisoi , Diptiranjan Rout , P. Janardhan , K. Fujiki , Dibyendu Chakrabarty , Karan Sahu

The advent of helioseismology has determined in detail the average rotation rate of the Sun as a function of radius and latitude. These data immediately reveal two striking boundary layers of shear in the solar convection zone (CZ): a…

Solar and Stellar Astrophysics · Physics 2019-03-06 Loren I. Matilsky , Bradley W. Hindman , Juri Toomre

Both coronal holes and active regions are source regions of the solar wind. The distribution of these coronal structures across both space and time is well known, but it is unclear how much each source contributes to the solar wind. In this…

Solar and Stellar Astrophysics · Physics 2021-08-11 D. Stansby , L. M. Green , L. van Driel-Gesztelyi , T. S. Horbury

A new method for automated detection of polar coronal holes is presented. This method, called perimeter tracing, uses a series of 171, 195, and 304 \AA\ full disk images from the Extreme ultraviolet Imaging Telescope (EIT) on SOHO over…

Solar and Stellar Astrophysics · Physics 2015-05-13 Michael S. Kirk , W. Dean Pesnell , C. Alex Young , Shea A. Hess Webber

The dependence of the sources and properties of the near-Earth solar wind on solar cycle activity is an important issue in solar and space physics. We use the improved two-step mapping procedure that takes into account the initial…

Solar and Stellar Astrophysics · Physics 2024-07-02 Xinzheng Shi , Hui Fu , Zhenghua Huang , Limei Yan , Chi Ma , Chenxi Huangfu , Hongqiang Song , Lidong Xia

Coronal waves, significant solar phenomena, act as diagnostic tools for scientists studying solar atmosphere properties. Here, we present a novel observation detailing how a coronal wave event, associated with an X5.0 class flare,…

Helioseismology has revealed that the angular velocity of the Sun increases with depth in the outermost 35 Mm of the Sun. Recently, we have shown that the logarithmic radial gradient ($\rm d\ln\Omega/\rm d\ln r $) in the upper 10~Mm is…

Solar and Stellar Astrophysics · Physics 2016-11-02 Atefeh Barekat , Jesper Schou , Laurent Gizon

Solar coronal holes are sources of high-speed solar wind streams, which cause persistent geomagnetic activity especially at high latitudes. Here we estimate seasonal solar wind speeds at 1 AU for the last 100 years using high-latitude…

Space Physics · Physics 2017-02-22 Kalevi Mursula , Lauri Holappa , Renata Lukianova

We present a statistical analysis for the characteristics and radial evolution of linear magnetic holes (LMHs) in the solar wind from 0.166 to 0.82 AU using Parker Solar Probe observations of the first two orbits. It is found that the LMHs…

Space Physics · Physics 2021-02-17 L. Yu , S. Y. Huang , Z. G. Yuan , K. Jiang , Q. Y. Xiong , S. B. Xu , Y. Y. Wei , J. Zhang , Z. H. Zhang

We derive a simple analytical model for the propagation of HSSs from the Sun to Earth and thereby show how the area of coronal holes and the size of their boundary regions affect the HSS velocity, temperature, and density near Earth. We…

Coronal holes are the observational manifestation of the solar magnetic field open to the heliosphere and are of pivotal importance for our understanding of the origin and acceleration of the solar wind. Observations from space missions…

The differential rotation of the solar corona for the period 1976-2004 was studied as a function of the distance from the center of the Sun. For this study, we developed a method using the coronal magnetic field as a tracer. The field in a…

Solar and Stellar Astrophysics · Physics 2018-09-19 O. G. Badalyan , V. N. Obridko

Coronal holes are the coolest and darkest regions of the solar atmosphere, as observed both on the solar disk and above the solar limb. Coronal holes are associated with rapidly expanding open magnetic fields and the acceleration of the…

Solar and Stellar Astrophysics · Physics 2011-09-21 D. Banerjee , G. R. Gupta , L. Teriaca

Coronal heating is a big question for modern astronomy. Daily measurement of 985 solar spectral irradiances (SSIs) at the spectral intervals 1-39 nm and 116-2416 nm during March 1 2003 to October 28 2017 is utilized to investigate…

Solar and Stellar Astrophysics · Physics 2019-04-24 KJ Li , JC Xu , ZQ Yin , W Feng

In the present work, we perform time-series analysis on the latitude bins of the solar full disk (SFD) images of Nobeyama Radioheliograph (NoRH) at 17 GHz. The flux modulation method traces the passage of radio features over the solar disc…

Solar and Stellar Astrophysics · Physics 2015-05-14 Satish Chandra , Hari Om Vats , K. N. Iyer

In-situ measurements by several spacecraft have revealed that the solar wind is frequently perturbed by transient structures (magnetic folds, jets, waves, flux-ropes) that propagate rapidly away from the Sun over large distances. Parker…

Solar and Stellar Astrophysics · Physics 2021-09-15 R. F. Pinto , N. Poirier , A. P. Rouillard , A. Kouloumvakos , L. Griton , N. Fargette , R. Kieokaew , B. Lavraud , A. S. Brun

Solar internal rotation at high latitudes is poorly constrained by acoustic-mode helioseismology. Global inertial modes observed on the Sun are highly sensitive to solar differential rotation and may provide new diagnostics of rotation in…

Solar and Stellar Astrophysics · Physics 2026-05-20 Prithwitosh Dey , Laurent Gizon , Yuto Bekki

This paper presents results of comparison between observations of coronal holes in the UV (SOHO EIT) and microwave emission (17, 5.7 GHz, 327 and 150.9 MHz, NoRH, SSRT and Nancy radioheliographs), and solar wind parameters, according to the…

Solar and Stellar Astrophysics · Physics 2015-05-20 D. Prosovetsky , I. Myagkova

In the era of space exploration, coronal holes on the sun play a significant role due to their impact on satellites and aircraft through their open magnetic fields and increased solar wind emissions. This study employs computer vision…

Solar and Stellar Astrophysics · Physics 2024-08-01 Juyoung Yun , Jungmin Shin