scholarly journals Velocities Observed in Supergranules

1976 ◽  
Vol 71 ◽  
pp. 121-134
Author(s):  
S. P. Worden ◽  
G. W. Simon
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Convection Zone ◽  
Convective Motion ◽  
Diode Array ◽  
Sacramento Peak ◽  
Sacramento Peak Observatory ◽  
And Diffusion ◽  
Time Sequences ◽  
Flux Redistribution

The evolution of the velocity and magnetic fields associated with supergranulation has been investigated using the Sacramento Peak Observatory Diode Array Magnetograph. The observations consist of time sequences of simultaneous velocity, magnetic field, and chromospheric network measurements. From these data it appears that the supergranular velocity cells have lifetimes in excess of 30 h. Magnetic field motions associated with supergranulation were infrequent and seem to be accompanied by changes in the velocity field. More prevalent was the slow dissipation and diffusion of stationary flux points. These observations suggest that surface motions do not exhibit the detailed flux redistribution expected in the random-walk diffusion of magnetic fields. It is suggested that the surface motions are only the reflection of magnetic field-convective motion interactions which occur deeper in the convection zone.

V. Heating and Dynamics of Chromosphere and Corona

1988 ◽  
Vol 20 (1) ◽  
pp. 100-102
Author(s):  
G.E. Brueckner
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Acoustic Waves ◽  
Convection Zone ◽  
Flux Tubes ◽  
Magnetic Structures ◽  
Convective Motions ◽  
Field Lines ◽  
The Magnetic Field

The crucial role of magnetic fields in any mechanism to heat the outer solar atmosphere has been generally accepted by all authors. However, there is still no agreement about the detailed function of the magnetic field. Heating mechanisms can be divided up into 4 classes: (I) The magnetic field plays a passive role as a suitable medium for the propagation of Alfvén waves from the convection zone into the corona (Ionson, 1984). (II) In closed magnetic structures the slow random shuffling of field lines by convective motions below the surface induces electric currents in the corona which heat it by Joule dissipation (Heyvaerts and Priest, 1984). (Ill) Emerging flux which is generated in the convection zone reacts with ionized material while magnetic field lines move through the chromosphere, transition zone and corona. Rapid field line annihilation, reconnection and drift currents result in heating and material ejection (Brueckner, 1987; Brueckner et al., 1987; Cook et al., 1987). (IV) Acoustic waves which could heat the corona can be guided by magnetic fields. Temperature distribution, wave motions and shock formation are highly dependent on the geometry of the flux tubes (Ulmschneider and Muchmore, 1986; Ulmschneider, Muchmore and Kalkofen, 1987).

scholarly journals Helicity–vorticity turbulent pumping of magnetic fields in the solar dynamo

2012 ◽  
Vol 8 (S294) ◽  
pp. 367-368
Author(s):  
V. V. Pipin
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Differential Rotation ◽  
Large Scale ◽  
Convection Zone ◽  
Solar Dynamo ◽  
Solar Convection Zone ◽  
Solar Convection ◽  
Large Scale Magnetic Field ◽  
Convective Motions

AbstractThe interaction of helical convective motions and differential rotation in the solar convection zone results in turbulent drift of a large-scale magnetic field. We discuss the pumping mechanism and its impact on the solar dynamo.

Probing solar-cycle variations of magnetic fields in the convection zone using meridional flows

2019 ◽  
Vol 15 (S354) ◽  
pp. 160-165
Author(s):  
Chia-Hsien Lin ◽  
Dean-Yi Chou
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Convection Zone ◽  
Deep Convection ◽  
Meridional Flow ◽  
Meridional Plane ◽  
Solar Magnetic Fields ◽  
Magnetic Field Effects ◽  
Astrophysical Journal ◽  
The Magnetic Field

AbstractSolar magnetic fields are believed to originate from the base of convection zone. However, it has been difficult to obtain convincing observational evidence of the magnetic fields in the deep convection zone. The goal of this study is to investigate whether solar meridional flows can be used to detect the magnetic-field effects. Meridional flows are axisymmetric flows on the meridional plane. Our result shows that the flow pattern in the entire convection zone changes significantly from solar minimum to maximum. The changes all centered around active latitudes, suggesting that the magnetic fields are responsible for the changes. The results indicate that the meridional flow can be used to detect the effects of magnetic field in the deep convection zone.The results have been published in the Astrophysical Journal (lc2018).

scholarly journals A New View of the Magnetic Sun

2003 ◽  
Vol 210 ◽  
pp. 195-207
Author(s):  
A. Title
Keyword(s):  
Magnetic Field ◽  
Convection Zone ◽  
Magnetic Activity ◽  
Line Of Sight ◽  
Density Structure ◽  
Dynamo Action ◽  
Single Temperature ◽  
Emergence Rate ◽  
The One ◽  
Time Sequences

Developments in instrumentation, numerical simulations, and theory are rapidly changing our view of solar magnetism. There are now observations that show magnetic field emerging on all convective scales. The emergence rate replaces the quiet Sun flux in less than 12 hours and even active region and sunspot fields are replaced in less than a month. There is evidence for local dynamo action suggesting that a bottom to a convection zone is not required for stellar magnetic activity. It is now recognized that 3D magnetic reconnection is fundamentally different from 2D. Time sequences of the one arc second spatial resolution TRACE images show that the temperature and density structure of the corona changes as fast as radiation and conduction allow. Because adjacent loops are observed in a range of temperatures that span at least 30 000 to 2 500 000 K, there is a inter mixture of temperatures regimes throughout the corona. Consequently, there is no line of sight through the corona that can be characterized by a single temperature and density. It would be surprising if other stars or other astrophysical systems with magnetic fields were simpler than the solar atmosphere.

scholarly journals Magnetic perturbations to stellar oscillation eigenfrequencies

1988 ◽  
Vol 123 ◽  
pp. 155-160
Author(s):  
D.O. Gough ◽  
M.J. Thompson
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Thin Layer ◽  
Convection Zone ◽  
Toroidal Magnetic Field ◽  
The Sun ◽  
Asymptotic Estimates ◽  
Magnetic Perturbations ◽  
Stellar Oscillation

Magnetic fields contribute to the splitting of the degeneracy of modes of like order and degree. The splitting is estimated for some simple hypothetical toroidal magnetic field configurations in the sun, and the results are compared with previous asymptotic estimates. Splitting by a field confined to a thin layer at the base of the convection zone is found not to agree with recent measurements.

scholarly journals Formation of Arching Flux Tubes at the Base of the Solar Convection Zone

2001 ◽  
Vol 203 ◽  
pp. 273-275
Author(s):  
Y. Fan
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Linear Growth ◽  
Convection Zone ◽  
Active Regions ◽  
Solar Convection Zone ◽  
Flux Tubes ◽  
Solar Convection ◽  
Neutrally Buoyant ◽  
Dynamo Process

Solar active regions are believed to correspond to the topmost portions of Ω-shaped arching flux tubes that have risen buoyantly from the base of the solar convection zone, where strong toroidal magnetic fields are being generated by the dynamo process. The development of such emerging Ω-loops is likely a result of the buoyant instability associated with the submerged toroidal magnetic field. Using an anelastic MHD code, we simulate the formation of buoyant, arching flux tube structures as a result of the non-linear growth of the undular instability of a neutrally buoyant layer of horizontal, unidirectional magnetic field at the base of the solar convection zone.

scholarly journals A search of the effects of magnetic field in the solar five-minute oscillations

1988 ◽  
Vol 123 ◽  
pp. 151-154
Author(s):  
S. V. Vorontsov
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Magnetic Fields ◽  
Convection Zone ◽  
Solar Convection Zone ◽  
Solar Convection

An overshoot region near the base of the solar convection zone may be the region where intense magnetic fields are stored during the solar cycle (Spiegel and Weiss, 1980; Schmitt and Rosner, 1983; Pidatella and Stix, 1986). In this report we study the possible influence of such a field on the frequencies of the solar five-minute oscillations.

scholarly journals The Transfer of Large-scale Magnetic Field by Radial Inhomogeneity of the Material Density in the Rotating Convection Zone

1991 ◽  
Vol 130 ◽  
pp. 190-192
Author(s):  
V.N. Krivodubskij ◽  
L.L. Kichatinov
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Large Scale ◽  
Convection Zone ◽  
Turbulent Plasma ◽  
The Sun ◽  
Material Density ◽  
Large Scale Magnetic Field ◽  
Radial Inhomogeneity ◽  
The Mean

AbstractThe influence of rotation on the transfer of the mean magnetic field of the Sun, caused by the radial inhomogeneity of the solar turbulent plasma density, is investigated. It turns out that the transfer directions of the poloidal and toroidal magnetic fields do not coincide.

scholarly journals Playing Music with Magnetic Fields

2002 ◽  
Vol 185 ◽  
pp. 482-483
Author(s):  
C. Foullon
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Field Strength ◽  
Convection Zone ◽  
Activity Cycle ◽  
Solar Activity Cycle ◽  
Global Mode ◽  
Frequency Shifts ◽  
Magnetic Layers ◽  
Field Lines

AbstractThrough an increase in magnetic field strength, solar magnetic fields in the atmosphere or subsurface of the Sun can explain the frequency shifts observed on the time scale of the solar activity cycle. A separate study of the contribution of internal magnetic layers clarifies the relative importance of these effects. However, at the base of the convection zone, the cyclical change of orientation of magnetic field lines has a larger effect on global mode frequencies than an increase in field strength alone.

Calculated Coronal Magnetic Fields and Their Comparison with the Coronal Structures as Observed during Five Solar Eclipses

1994 ◽  
Vol 144 ◽  
pp. 559-564
Author(s):  
P. Ambrož ◽  
J. Sýkora
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Magnetic Fields ◽  
Solar Corona ◽  
Coronal Magnetic Field ◽  
Coronal Magnetic Fields ◽  
Solar Eclipses ◽  
Coronal Structures

AbstractWe were successful in observing the solar corona during five solar eclipses (1973-1991). For the eclipse days the coronal magnetic field was calculated by extrapolation from the photosphere. Comparison of the observed and calculated coronal structures is carried out and some peculiarities of this comparison, related to the different phases of the solar cycle, are presented.

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