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The spectroscopic observations presented here were acquired during the 2017 August 21 total solar eclipse with a three-channel partially multiplexed imaging spectrometer (3PAMIS) operating at extremely high orders ($>$ 50). The 4 $R_\odot$…

Solar and Stellar Astrophysics · Physics 2024-03-18 Yingjie Zhu , Shadia R. Habbal , Adalbert Ding , Bryan Yamashiro , Enrico Landi , Benjamin Boe , Sage Constantinou , Michael Nassir

The origin of the heliospheric magnetic flux on the Sun, and hence the origin of the solar wind, is a topic of hot debate.While the prevailing view is that the solar wind originates from outside coronal streamer helmets, there also exists…

Solar and Stellar Astrophysics · Physics 2015-06-05 Bo Li , Xing Li , Hui Yu

Non-linear force-free extrapolations are a common approach to estimate the 3D topology of coronal magnetic fields based on photospheric vector magnetograms. The force-free assumption is a valid approximation at coronal heights, but for the…

We undertake a first attempt towards a consistent reconstruction of the coronal magnetic field and the coronal density structure. We consider a stationary solar corona which has to obey the equations of magnetohydrostatics. We solve these…

Astrophysics · Physics 2009-06-25 T. Wiegelmann , B. Inhester

Coronal seismology is extensively used to estimate properties of the corona, e.g. the coronal magnetic field strength are derived from oscillations observed in coronal loops. We present a three-dimensional coronal simulation including a…

Solar and Stellar Astrophysics · Physics 2015-09-23 Feng Chen , Hardi Peter

We study the magnetic field and current structure associated with a coronal loop. Through this we investigate to what extent the assumptions of a force-free magnetic field break down and where they might be justified. We analyse a 3D MHD…

Solar and Stellar Astrophysics · Physics 2017-12-05 Jörn Warnecke , Feng Chen , Sven Bingert , Hardi Peter

In the present work we study evolution of magnetic helicity in the solar corona. We compare the rate of change of a quantity related to the magnetic helicity in the corona to the flux of magnetic helicity through the photosphere and find…

Solar and Stellar Astrophysics · Physics 2021-06-29 A. Malanushenko , M. H. Yusuf , D. W. Longcope

The knowledge of magnetic topology is the key to understand magnetic energy release in astrophysics. Based on observed vector magnetograms, we have determined threedimensional (3D) topology skeleton of the magnetic fields in active region…

Astrophysics · Physics 2009-11-13 Hui Zhao , Jing-Xiu Wang , Jun Zhang , Chi-Jie Xiao , Hai-Min Wang

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

We will use new data from the High-resolution Coronal Imager (Hi-C) with unprecedented spatial resolution of the solar corona to investigate the structure of coronal loops down to 0.2 arcsec. During a rocket flight Hi-C provided images of…

Solar and Stellar Astrophysics · Physics 2015-06-16 H. Peter , S. Bingert , J. A. Klimchuk , C. de Forest , J. W. Cirtain , L. Golub , A. R. Winebarger , K. Kobayashi , K. E. Korreck

We perform MHD modeling of a single bright coronal loop to include the interaction with a non-uniform magnetic field. The field is stressed by random footpoint rotation in the central region and its energy is dissipated into heating by…

Solar and Stellar Astrophysics · Physics 2016-10-12 F. Reale , S. Orlando , M. Guarrasi , A. Mignone , G. Peres , A. W. Hood , E. R. Priest

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

Magnetic field is the key physical quantity in solar physics as it controls all kinds of solar activity, ranging from nanoflares to big flares and coronal mass ejections (CMEs). However, so far only the magnetic field on the solar surface…

Solar and Stellar Astrophysics · Physics 2025-11-21 P. F. Chen

As the observational signature of the footprints of solar magnetic field lines open into the heliosphere, coronal holes provide a critical measure of the structure and evolution of these lines. Using a combination of Solar and Heliospheric…

Solar and Stellar Astrophysics · Physics 2016-12-23 Chris Lowder , Jiong Qiu , Robert Leamon

Coronal rain is the well-known phenomenon in which hot plasma high in the Sun's corona undergoes rapid cooling (from > 10^6 K to < 10^4 K), condenses, and falls to the surface. Coronal rain appears frequently in active region coronal loops…

Solar and Stellar Astrophysics · Physics 2019-04-22 E. I. Mason , S. K. Antiochos , N. M. Viall

In this study, we investigate in detail the photospheric magnetic structure of 98 coronal holes using line-of-sight magnetograms of SDO/HMI, and for a subset of 42 coronal holes using HINODE/SOT G-band filtergrams. We divided the magnetic…

Solar and Stellar Astrophysics · Physics 2019-09-10 Stefan J. Hofmeister , Dominik Utz , Stephan G. Heinemann , Astrid Veronig , Manuela Temmer

Magnetic fields in the solar corona are responsible for a wide range of phenomena. However, any direct measurements of the coronal magnetic fields are very difficult due to lack of suitable spectral lines, weak magnetic fields, and high…

Solar and Stellar Astrophysics · Physics 2013-10-28 P. Vemareddy , A. Ambastha , T. Wiegelmann

It is widely believed that loops observed in the solar atmosphere trace out magnetic field lines. However, the degree to which magnetic field extrapolations yield field lines that actually do follow loops has yet to be studied…

Solar and Stellar Astrophysics · Physics 2018-06-27 Harry P. Warren , Nicholas A. Crump , Ignacio Ugarte-Urra , Xudong Sun , Markus J. Aschwanden , Thomas Wiegelmann

We have examined the global structure of the solar magnetic field using data from the FeI spectral line at {\lambda}5250.2{\AA} obtained at the 150-foot tower telescope at the Mt. Wilson Observatory (MWO). For each point on the solar…

Solar and Stellar Astrophysics · Physics 2015-06-15 Roger K. Ulrich , Tham Tran

The origin and evolution of the magnetic helicity in the solar corona are not well understood. For instance, the magnetic helicity of an active region is often about $10^{42}$ Mx$^2$ ($10^{26}$ Wb$^{2}$), but the observed processes whereby…

Solar and Stellar Astrophysics · Physics 2009-11-13 S. Regnier