Three-phase Evolution of a Coronal Hole. II. The Magnetic Field

被引:20
作者
Heinemann, Stephan G. [1 ]
Hofmeister, Stefan J. [1 ]
Veronig, Astrid M. [1 ]
Temmer, Manuela [1 ]
机构
[1] Karl Franzens Univ Graz, Inst Phys, Univ Pl 5, A-8010 Graz, Austria
关键词
Sun: corona; Sun: magnetic fields; Sun: photosphere; SOLAR-WIND SPEED; ORIGIN; DYNAMO; FLUX; FUNNELS; FLOWS; CYCLE;
D O I
10.3847/1538-4357/aad095
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We investigate the magnetic characteristics of a persistent coronal hole (CH) extracted from EUV imagery using Heliospheric and Magnetic Imager filtergrams over the period 2012 Febmary-October. The magnetic field, its distribution, and the magnetic fine structure in the form of flux tubes (FTs) are analyzed in different evolutionary states of the CH. We find a strong linear correlation between the magnetic properties (e.g., signed/unsigned magnetic field strength) and the area of the CH. As such, the evolutionary pattern in the magnetic field clearly follows a three-phase evolution (growing, maximum, and decaying) as found from EUV data (Part I). This evolutionary process is most likely driven by strong FTs with a mean magnetic field strength exceeding 50 G. During the maximum phase they entail up to 72% of the total signed magnetic flux of the CH, but only cover up to 3.9% of the total CH area, whereas during the growing and decaying phases, strong FTs entail 54%-60% of the signed magnetic flux and cover around 1%-2% of the CH's total area. We conclude that small-scale structures of strong unipolar magnetic field are the fundamental building blocks of a CH and govern its evolution.
引用
收藏
页数:10
相关论文
共 50 条
[41]   Magnetohydrodynamics dynamical relaxation of coronal magnetic fields II. 2D magnetic X-points [J].
Fuentes-Fernandez, J. ;
Parnell, C. E. ;
Hood, A. W. .
ASTRONOMY & ASTROPHYSICS, 2011, 536
[42]   Investigation of the Coronal Magnetic Field Using a Type II Solar Radio Burst [J].
Vasanth, V. ;
Umapathy, S. ;
Vrsnak, Bojan ;
Zic, Tomislav ;
Prakash, O. .
SOLAR PHYSICS, 2014, 289 (01) :251-261
[43]   The velocity field of sunspot penumbrae II. Return flow and magnetic fields of opposite polarity [J].
Franz, M. ;
Schlichenmaier, R. .
ASTRONOMY & ASTROPHYSICS, 2013, 550
[44]   Coronal hole boundaries evolution at small scales II. XRT view. Can small-scale outflows at CHBs be a source of the slow solar wind? [J].
Subramanian, S. ;
Madjarska, M. S. ;
Doyle, J. G. .
ASTRONOMY & ASTROPHYSICS, 2010, 516
[45]   The supernova-regulated ISM - II. The mean magnetic field [J].
Gent, F. A. ;
Shukurov, A. ;
Sarson, G. R. ;
Fletcher, A. ;
Mantere, M. J. .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 2013, 430 (01) :L40-L44
[46]   Magnetic shear and cross-field currents: Roles in the evolution of the pre-coronal mass ejection corona [J].
Wolfson, R ;
Dlamini, B .
ASTROPHYSICAL JOURNAL, 1999, 526 (02) :1046-1051
[47]   The long-term evolution of AR 7978:: The scalings of the coronal plasma parameters with the mean photospheric magnetic field [J].
van Driel-Gesztelyi, L ;
Démoulin, P ;
Mandrini, CH ;
Harra, L ;
Klimchuk, JA .
ASTROPHYSICAL JOURNAL, 2003, 586 (01) :579-591
[48]   The Coronal Global Evolutionary Model: Using HMI Vector Magnetogram and Doppler Data to Determine Coronal Magnetic Field Evolution [J].
Hoeksema, J. Todd ;
Abbett, William P. ;
Bercik, David J. ;
Cheung, Mark C. M. ;
DeRosa, Marc L. ;
Fisher, George H. ;
Hayashi, Keiji ;
Kazachenko, Maria D. ;
Liu, Yang ;
Lumme, Erkka ;
Lynch, Benjamin J. ;
Sun, Xudong ;
Welsch, Brian T. .
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, 2020, 250 (02)
[49]   The magnetic field vector of the Sun-as-a-star - II. Evolution of the large-scale vector field through activity cycle 24 [J].
Vidotto, A. A. ;
Lehmann, L. T. ;
Jardine, M. ;
Pevtsov, A. A. .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 2018, 480 (01) :477-487
[50]   Dynamics of solar active regions II. Oscillations observed with MDI and their relation to the magnetic field topology [J].
Muglach, K ;
Hofmann, A ;
Staude, J .
ASTRONOMY & ASTROPHYSICS, 2005, 437 (03) :1055-1060