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The magnetic field permeating the solar atmosphere is generally thought to provide the energy for much of the activity seen in the solar corona, such as flares, coronal mass ejections (CMEs), etc. To overcome the unavailability of coronal…

Solar and Stellar Astrophysics · Physics 2015-06-17 Tilaye Tadesse , T. Wiegelmann , S. Gosain , P. MacNeice , Alexei A. Pevtsov

The properties of the solar wind measured in-situ in the heliosphere are largely controlled by energy deposition in the solar. Previous studies have shown that long duration and large scale magnetic structures show an inverse relation…

Solar and Stellar Astrophysics · Physics 2024-10-30 J-B. Dakeyo , A. P. Rouillard , V. Réville , P. Démoulin , M. Maksimovic , A. Chapiron , R. F. Pinto , P. Louarn

(Abridged) Aim: We attempt to determine robust estimates of the heliospheric magnetic flux ($\Phi_H$) using Parker Solar Probe (PSP) data, analyze how susceptible this is to overestimation compared to the true open flux ($\Phi_{open}$),…

For the first time we reconstruct the magnetic helicity density of global axisymmetric field of the Sun using method proposed by Brandenburg et al. (2003) and Pipin et al. (2013). To determine the components of the vector potential, we…

Solar and Stellar Astrophysics · Physics 2015-06-18 V. V. Pipin , A. A. Pevtsov

We analyze data from the Solar and Heliospheric Observatory to produce global maps of coronal outflow velocities and densities in the regions where the solar wind is undergoing acceleration. The maps use UV and white light coronal data…

Solar and Stellar Astrophysics · Physics 2015-06-03 Leonard Strachan , Alexander V. Panasyuk , John L. Kohl , Philippe Lamy

Aims. Working towards improved space weather predictions, we aim to quantify how the critical height at which the torus instability drives coronal mass ejections (CMEs) varies over time in a sample of solar active regions. Methods. We model…

Solar and Stellar Astrophysics · Physics 2022-09-07 Alexander W. James , David R. Williams , Jennifer O'Kane

Disconnection of open magnetic flux by reconnection is required to balance the injection of open flux by CMEs and other eruptive events. Making use of recent advances in heliospheric background subtraction, we have imaged many abrupt…

Solar and Stellar Astrophysics · Physics 2015-06-03 C. E. DeForest , T. A. Howard , D. J. McComas

The solar surface magnetic field is fundamental for modeling the coronal magnetic field, studying the solar dynamo, and predicting solar cycle strength. We perform a continuous simulation of the surface magnetic field from 2010 to 2024,…

Solar and Stellar Astrophysics · Physics 2025-06-03 Ruihui Wang , Jie Jiang , Yukun Luo

We investigate the relationship between the monthly averaged maximal speeds of coronal mass ejections (CMEs), international sunspot number (ISSN), and the geomagnetic Dst and Ap indices covering the 1996-2008 time interval (solar cycle 23).…

Solar and Stellar Astrophysics · Physics 2011-11-18 A. Kilcik , V. B. Yurchyshyn , V. Abramenko , P. R. Goode , N. Gopalswamy , A. Ozguc , J. P. Rozelot

We have measured the physical properties of polar coronal holes from the minimum activity phase of solar cycle 23 (1996-1997) to the present minimum of solar cycle 24 (2007-2009) using the UVCS instrument on SOHO. Observations in H I Lyman…

Solar and Stellar Astrophysics · Physics 2010-05-19 M. P. Miralles , S. R. Cranmer , A. V. Panasyuk , M. Uzzo

Sun-as-a-star coronal plasma composition, derived from full-Sun spectra, and the F10.7 radio flux (2.8 GHz) have been shown to be highly correlated (r = 0.88) during solar cycle 24. However, this correlation becomes nonlinear during…

Coronal holes (CHs) are the source of high-speed streams (HSSs) in the solar wind, whose interaction with the slow solar wind creates corotating interaction regions (CIRs) in the heliosphere. Whenever the CIRs hit the Earth, they can cause…

Solar and Stellar Astrophysics · Physics 2023-01-18 Simona Nitti , Tatiana Podladchikova , Stefan J. Hofmeister , Astrid M. Veronig , Giuliana Verbanac , Mario Bandić

Variations in the propagation of globally-propagating disturbances (commonly called "EIT waves") through the low solar corona offer a unique opportunity to probe the plasma parameters of the solar atmosphere. Here, high-cadence observations…

Solar and Stellar Astrophysics · Physics 2015-06-16 David M. Long , David R. Williams , Stéphane Régnier , Louise K. Harra

An empirical model for forecasting solar wind speed related geomagnetic events is presented here. The model is based on the estimated location and size of solar coronal holes. This method differs from models that are based on photospheric…

Astrophysics · Physics 2008-11-26 S. Robbins , C. J. Henney , J. W. Harvey

In this paper, we study two sets of local geomagnetic indices from 26 stations using the principal component (PC) and the independent component (IC) analysis methods. We demonstrate that the annually averaged indices can be accurately…

Solar and Stellar Astrophysics · Physics 2015-01-16 Lauri Holappa , Kalevi Mursula , Timo Asikainen

The Sun's open-closed flux boundary (OCB) separates closed and open magnetic field lines, and is the site for interchange magnetic reconnection processes thought to be linked to the origin of the slow solar wind (SSW). We analyze the global…

Solar and Stellar Astrophysics · Physics 2025-05-27 Chloe P. Wilkins , David I. Pontin , Anthony R. Yeates , Spiro K. Antiochos , Hannah Schunker , Bishnu Lamichhane

Observations of surface magnetic fields are now within reach for many stellar types thanks to the development of Zeeman-Doppler Imaging. These observations are extremely useful for constraining rotational evolution models of stars, as well…

Solar and Stellar Astrophysics · Physics 2015-09-24 Victor Réville , Allan Sacha Brun , Antoine Strugarek , Sean P. Matt , Jérôme Bouvier , Colin P. Folsom , Pascal Petit

Flux ropes (FRs) ejected from the Sun may change their geometrical orientation during their evolution which directly affects their geoeffectiveness. Therefore, it is crucial to understand how solar FRs evolve in the heliosphere to improve…

Space Physics · Physics 2014-01-27 Alexey Isavnin , Angelos Vourlidas , Emilia K. J. Kilpua

The solar corona is much hotter than the photosphere and chromosphere, but the physical mechanism responsible for heating the coronal plasma remains unidentified yet. The thermal microwave emission, which is produced in strong magnetic…

Solar and Stellar Astrophysics · Physics 2025-08-27 Alexey A. Kuznetsov , Gregory D. Fleishman , Gelu M. Nita , Sergey A. Anfinogentov

The dynamics of the solar wind depends intrinsically on the structure of the global solar magnetic field, which undergoes fundamental changes over the 11-yr solar cycle. For instance, the wind terminal velocity is thought to be…

Solar and Stellar Astrophysics · Physics 2017-11-29 Victor Réville , Allan Sacha Brun