Are there local dynamo in solar polar region?

2019 ◽  
Vol 15 (S354) ◽  
pp. 123-126
Author(s):  
Chunlan Jin
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Polar Region ◽  
Toroidal Magnetic Field ◽  
Polar Magnetic Field ◽  
Random State

AbstractPolar magnetic field, as a component produced by the global dynamo, is thought to be the remant of toroidal magnetic field transported poleward from Sun’s active belt. With the improvement of instruments, more and more observations are challenging the viewpoint. Recently, we identify the bipolar magnetic emergences (BMEs) in the polar region, and find that the distribution of the magnetic axes for these BMEs shows random state, which does not follow the Joy’s law of active region. The result implies the possible existence of local dynamo in the solar polar region.

scholarly journals Polar magnetic field reversals on the Sun

2006 ◽  
Vol 2 (14) ◽  
pp. 273-274 ◽  
Author(s):  
Elena E. Benevolenskaya
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Polar Region ◽  
Small Scale ◽  
The Sun ◽  
Field Reversal ◽  
Polar Magnetic Field ◽  
The North ◽  
Magnetic Elements ◽  
Polar Magnetic Fields

AbstractThe polar magnetic fields on the Sun have been an attractive subject for solar researches since Babcock measured them in solar cycle 19. One of the remarkable features of the polar magnetic fields is their reversal during the maxima of 11-year sunspot cycles. I have present results of the investigations of the polar magnetic field using SOHO-mdi data. It is found, that the polar magnetic field reversal is detected with mdi data for polar region within 78°–88°. The North Pole has changed polarity in CR1975 (April 2001). The South reversed later in CR1980 (September 2001). The total unsigned magnetic flux does not show the dramatic decreasing during the polar reversals due to omnipresent bi-polar small-scale magnetic elements. The observational and theoretical aspects of the polar magnetic field reversals are discussed.

Polar Magnetic Field Reversals of the Sun in Maunder Minimum

2000 ◽  
Vol 179 ◽  
pp. 193-196
Author(s):  
V. I. Makarov ◽  
A. G. Tlatov
Keyword(s):  
Magnetic Field ◽  
Maunder Minimum ◽  
The Sun ◽  
Annual Rings ◽  
Field Reversal ◽  
Polar Magnetic Field ◽  
Pine Trees ◽  
Using Data ◽  
Magnetic Field Reversal

AbstractA possible scenario of polar magnetic field reversal of the Sun during the Maunder Minimum (1645–1715) is discussed using data of magnetic field reversals of the Sun for 1880–1991 and the14Ccontent variations in the bi-annual rings of the pine-trees in 1600–1730 yrs.

scholarly journals Energetics of magnetic transients in a solar active region plage

2019 ◽  
Vol 623 ◽  
pp. A176 ◽  
Author(s):  
L. P. Chitta ◽  
A. R. C. Sukarmadji ◽  
L. Rouppe van der Voort ◽  
H. Peter
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Magnetic Flux ◽  
Numerical Simulations ◽  
Extreme Ultraviolet ◽  
Spatial Scales ◽  
Coronal Loops ◽  
The Sun ◽  
Flux Emergence ◽  
Transient Events

Context. Densely packed coronal loops are rooted in photospheric plages in the vicinity of active regions on the Sun. The photospheric magnetic features underlying these plage areas are patches of mostly unidirectional magnetic field extending several arcsec on the solar surface. Aims. We aim to explore the transient nature of the magnetic field, its mixed-polarity characteristics, and the associated energetics in the active region plage using high spatial resolution observations and numerical simulations. Methods. We used photospheric Fe I 6173 Å spectropolarimetric observations of a decaying active region obtained from the Swedish 1-m Solar Telescope (SST). These data were inverted to retrieve the photospheric magnetic field underlying the plage as identified in the extreme-ultraviolet emission maps obtained from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). To obtain better insight into the evolution of extended unidirectional magnetic field patches on the Sun, we performed 3D radiation magnetohydrodynamic simulations of magnetoconvection using the MURaM code. Results. The observations show transient magnetic flux emergence and cancellation events within the extended predominantly unipolar patch on timescales of a few 100 s and on spatial scales comparable to granules. These transient events occur at the footpoints of active region plage loops. In one case the coronal response at the footpoints of these loops is clearly associated with the underlying transient. The numerical simulations also reveal similar magnetic flux emergence and cancellation events that extend to even smaller spatial and temporal scales. Individual simulated transient events transfer an energy flux in excess of 1 MW m−2 through the photosphere. Conclusions. We suggest that the magnetic transients could play an important role in the energetics of active region plage. Both in observations and simulations, the opposite-polarity magnetic field brought up by transient flux emergence cancels with the surrounding plage field. Magnetic reconnection associated with such transient events likely conduits magnetic energy to power the overlying chromosphere and coronal loops.

Magnetic field topology by MDI data: Active region

2012 ◽  
Vol 38 (8) ◽  
pp. 531-542 ◽  
Author(s):  
N. G. Makarenko ◽  
I. S. Knyazeva ◽  
L. M. Karimova
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Magnetic Field Topology

scholarly journals The Persistence of Apparent Non-Magnetostatic Equilibrium in NOAA 11035

2014 ◽  
Vol 10 (S305) ◽  
pp. 35-41
Author(s):  
Sarah A. Jaeggli
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Strong Magnetic Field ◽  
Solar Atmosphere ◽  
Activity Cycle ◽  
Opposite Polarity ◽  
Unusual Feature ◽  
Complete Picture

AbstractNOAA 11035 was a highly sheared active region that appeared in December 2009 early in the new activity cycle. The leading polarity sunspot developed a highly unusual feature in its penumbra, an opposite polarity pore with a strong magnetic field in excess of 3500 G along one edge, which persisted for several days during the evolution of the region. This region was well observed by both space- and ground-based observatories, including Hinode, FIRS, TRACE, and SOHO. These observations, which span wavelength and atmospheric regimes, provide a complete picture of this unusual feature which may constitute a force-free magnetic field in the photosphere which is produced by the reconnection of magnetic loops low in the solar atmosphere.

scholarly journals The Nonpotentiality of Active‐Region Coronae and the Dynamics of the Photospheric Magnetic Field

2005 ◽  
Vol 628 (1) ◽  
pp. 501-513 ◽  
Author(s):  
Carolus J. Schrijver ◽  
Marc L. DeRosa ◽  
Alan M. Title ◽  
Thomas R. Metcalf
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Photospheric Magnetic Field
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