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Coronal holes are large-scale structures in the solar atmosphere that feature a reduced temperature and density in comparison to the surrounding quiet Sun and are usually associated with open magnetic fields. We perform a differential…

Solar and Stellar Astrophysics · Physics 2021-03-01 Stephan G. Heinemann , Jonas Saqri , Astrid M. Veronig , Stefan J. Hofmeister , Manuela Temmer

Global magnetic field models use as input synoptic data, which usually show "aging effects" as the longitudinal 360{\deg} information is not obtained simultaneously. Especially during times of increased solar activity, the evolution of the…

Solar and Stellar Astrophysics · Physics 2021-10-04 Stephan G. Heinemann , Manuela Temmer , Stefan J. Hofmeister , Aleksandar Stojakovic , Laurent Gizon , Dan Yang

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

With the recent launch of the Hinode satellite our view of the nature and evolution of quiet-Sun regions has been improved. In light of the new high resolution observations, we revisit the study of the quiet Sun's topological nature.…

Astrophysics · Physics 2009-11-13 S. Regnier , C. E. Parnell , A. L. Haynes

The solar magnetic fields emerging from the photosphere into the chromosphere and corona are comprised of a combination of "closed" and "open" fields. The closed magnetic field lines are defined as those having both ends rooted in the solar…

Solar and Stellar Astrophysics · Physics 2023-04-18 C. Nick Arge , Andrew Leisner , Samantha Wallace , Carl J. Henney

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

Because of its distinctive compositional properties and variability, low-speed ($\lesssim 450$ km s$^{-1}$) solar wind is widely believed to originate from coronal streamers, unlike high-speed wind, which comes from coronal holes. An…

Solar and Stellar Astrophysics · Physics 2021-04-16 Y. -M. Wang , Y. -K. Ko

Coronal holes (CHs) are regions with unbalanced magnetic flux, and have been associated with open magnetic field (OMF) structures. However, it has been reported that some CHs do not intersect with OMF regions. To investigate the…

Solar and Stellar Astrophysics · Physics 2022-07-27 Guan-Han Huang , Chia-Hsien Lin , Lou-Chuang Lee

Parameters of magnetic flux distribution inside low-latitude coronal holes (CHs) were analyzed. A statistical study of 44 CHs based on Solar and Heliospheric Observatory (SOHO)/MDI full disk magnetograms and SOHO/EIT 284\AA images showed…

Solar and Stellar Astrophysics · Physics 2015-05-13 Valentina Abramenko , Vasyl Yurchyshyn , Hiroko Watanabe

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

Magnetic loops filled with hot plasma are the main building blocks of the solar corona. Usually they have lengths of the order of the barometric scale height in the corona that is 50 Mm. Previously it has been suggested that miniature…

Solar and Stellar Astrophysics · Physics 2017-03-15 Krzysztof Barczynski , Hardi Peter , Sabrina L. Savage

Small-scale ephemeral coronal holes may be a recurring feature on the solar disk, but have received comparatively little attention. These events are characterized by compact structure and short total lifetimes, substantially less than a…

Solar and Stellar Astrophysics · Physics 2019-08-07 Andrew R. Inglis , Rachel E. O'Connor , W. Dean Pesnell , Michael S. Kirk , Nishu Karna

We expand upon our paper (Rice and Yeates, 2021) which introduced `Outflow Fields': alternatives to the widely-used potential field source surface (PFSS) extrapolations of the Sun's coronal magnetic field which take into account the effect…

Solar and Stellar Astrophysics · Physics 2026-03-24 Oliver Rice , Anthony Yeates

Coronal holes (CHs) are darker than quiet Sun (QS) when observed in coronal channels. This study aims to understand the similarities and differences between CHs and QS in the transition region using the \ion{Si}{4}~1394~{\AA} line recorded…

Solar and Stellar Astrophysics · Physics 2021-02-17 Durgesh Tripathi , V. N. Nived , Sami K Solanki

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

Low and mid-latitude coronal holes (CHs) observed on the Sun during the current solar activity minimum (from September 21, 2006, Carrington rotation (CR) 2048, until June 26, 2009 (CR 2084)) were analyzed using {\it SOHO}/EIT and STEREO-A…

Solar and Stellar Astrophysics · Physics 2015-05-18 V. Abramenko , V. Yurchyshyn , J. Linker , Z. Mikic , J. Luhmann , C. Lee

Two extrapolation models of the solar coronal magnetic field are compared using magnetogram data from the SDO/HMI instrument. The two models, a horizontal current-current sheet-source surface (HCCSSS) model and a potential field-source…

Solar and Stellar Astrophysics · Physics 2016-05-25 William M. Arden , Aimee A. Norton , Xudong Sun , Xuepu Zhao

Magnetic loops are building blocks of the closed-field corona. While active region loops are readily seen in images taken at EUV and X-ray wavelengths, quiet Sun loops are seldom identifiable and therefore difficult to study on an…

Solar and Stellar Astrophysics · Physics 2015-06-05 Zhenguang Huang , Richard A. Frazin , Enrico Landi , Ward B. Manchester , Alberto M. Vásquez , Tamas I. Gombosi

Many scientists use coronal hole (CH) detections to infer open magnetic flux. Detection techniques differ in the areas that they assign as open, and may obtain different values for the open magnetic flux. We characterize the uncertainties…

The internal dynamics of the Sun generate magnetic and plasma structures in the photosphere and overlying atmosphere across a wide range of spatial scales. Identifying the critical spatial scale is essential for interpreting physical…

Solar and Stellar Astrophysics · Physics 2026-04-14 Ananya Hore , Prantika Bhowmik