The cyclical variation of energy flux and photospheric magnetic field strength from coronal holes

Solar Physics ◽  
1985 ◽  
Vol 102 (1-2) ◽  
pp. 177-190 ◽  
Author(s):  
David F. Webb ◽  
John M. Davis
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Energy Flux ◽  
Coronal Holes ◽  
Photospheric Magnetic Field ◽  
Cyclical Variation

Energy flux determines magnetic field strength of planets and stars

Nature ◽  
2009 ◽  
Vol 457 (7226) ◽  
pp. 167-169 ◽  
Author(s):  
Ulrich R. Christensen ◽  
Volkmar Holzwarth ◽  
Ansgar Reiners
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Energy Flux

Microwave Enhancement in Coronal Holes: Statistical Properties

2000 ◽  
Vol 179 ◽  
pp. 413-417
Author(s):  
N. Gopalswamy ◽  
K. Shibasaki ◽  
M. Salem
Keyword(s):  
Magnetic Field ◽  
Fine Structure ◽  
Field Strength ◽  
Brightness Temperature ◽  
Magnetic Field Strength ◽  
Coronal Holes ◽  
Life Time ◽  
Statistical Properties ◽  
Temperature Area

AbstractWe report on the statistical properties of the microwave enhancement (brightness temperature, area, fine structure, life time and magnetic field strength) in coronal holes observed over a period of several solar rotations.

scholarly journals Recovering the unsigned photospheric magnetic field from Ca II K observations

2019 ◽  
Vol 626 ◽  
pp. A114 ◽  
Author(s):  
Theodosios Chatzistergos ◽  
Ilaria Ermolli ◽  
Sami K. Solanki ◽  
Natalie A. Krivova ◽  
Fabrizio Giorgi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Power Law ◽  
Activity Level ◽  
Photospheric Magnetic Field ◽  
Stray Light ◽  
Magnetic Flux Density ◽  
Logarithmic Function

Context. A number of studies have aimed at defining the exact form of the relation between magnetic field strength and Ca II H and K core brightness. All previous studies have however been restricted to isolated regions on the solar disc or to a limited set of observations. Aims. We reassess the relationship between the photospheric magnetic field strength and the Ca II K intensity for a variety of surface features as a function of the position on the disc and the solar activity level. This relationship can be used to recover the unsigned photospheric magnetic field from images recorded in the core of Ca II K line. Methods. We have analysed 131 pairs of high-quality, full-disc, near-co-temporal observations from the Helioseismic and Magnetic Imager (SDO/HMI) and Precision Solar Photometric Telescope (Rome/PSPT) spanning half a solar cycle. To analytically describe the observationally determined relation, we considered three different functions: a power law with an offset, a logarithmic function, and a power-law function of the logarithm of the magnetic flux density. We used the obtained relations to reconstruct maps of the line-of-sight component of the unsigned magnetic field (unsigned magnetograms) from Ca II K observations, which were then compared to the original magnetograms. Results. We find that both power-law functions represent the data well, while the logarithmic function is good only for quiet periods. We see no significant variation over the solar cycle or over the disc in the derived fit parameters, independently of the function used. We find that errors in the independent variable, which are usually not accounted for, introduce attenuation bias. To address this, we binned the data with respect to the magnetic field strength and Ca II K contrast separately and derived the relation for the bisector of the two binned curves. The reconstructed unsigned magnetograms show good agreement with the original ones. Root mean square differences are less than 90 G. The results were unaffected by the stray-light correction of the SDO/HMI and Rome/PSPT data. Conclusions. Our results imply that accurately processed and calibrated Ca II K observations can be used to reconstruct unsigned magnetograms by using the relations derived in our study.

On the Configuration of the Magnetic Field of β CrB

1976 ◽  
Vol 32 ◽  
pp. 613-622
Author(s):  
I.A. Aslanov ◽  
Yu.S. Rustamov
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Radial Velocity ◽  
Magnetic Field Strength ◽  
Complex Shape ◽  
Rotation Period ◽  
Field Variation ◽  
Magnetic Field Variation ◽  
Secular Variations ◽  
The Magnetic Field

SummaryMeasurements of the radial velocities and magnetic field strength of β CrB were carried out. It is shown that there is a variability with the rotation period different for various elements. The curve of the magnetic field variation measured from lines of 5 different elements: FeI, CrI, CrII, TiII, ScII and CaI has a complex shape specific for each element. This may be due to the presence of magnetic spots on the stellar surface. A comparison with the radial velocity curves suggests the presence of a least 4 spots of Ti and Cr coinciding with magnetic spots. A change of the magnetic field with optical depth is shown. The curve of the Heffvariation with the rotation period is given. A possibility of secular variations of the magnetic field is shown.

2D analysis of magnetic field strength in GO SiFe steel sheets

1998 ◽  
Vol 08 (PR2) ◽  
pp. Pr2-579-Pr2-582 ◽  
Author(s):  
S. Tumanski ◽  
M. Stabrowski
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Steel Sheets

MAGNETIC FIELD, PRESSURE AND TEMPERATURE DEPENDENT OPTICAL PROPERTIES IN A GaAs 9.0 P 1.0 QUANTUM DOT

2014 ◽  
Vol 6 (2) ◽  
pp. 1178-1190
Author(s):  
A. JOHN PETER ◽  
Ada Vinolin
Keyword(s):  
Magnetic Field ◽  
Optical Properties ◽  
Quantum Dot ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Photon Energy ◽  
Nonlinear Optical ◽  
Binding Energies ◽  
Nonlinear Optical Properties ◽  
Optical Rectification

Simultaneous effects of magnetic field, pressure and temperature on the exciton binding energies are found in a 9.0 1.0 6.0 4.0 GaAs P / GaAs P quantum dot. Numerical calculations are carried out taking into consideration of spatial confinement effect. The cylindrical system is taken in the present problem with the strain effects. The electronic properties and the optical properties are found with the combined effects of magnetic field strength, hydrostatic pressure and temperature values. The exciton binding energies and the nonlinear optical properties are carried out taking into consideration of geometrical confinement and the external perturbations.Compact density approach is employed to obtain the nonlinear optical properties. The optical rectification coefficient is obtained with the photon energy in the presence of pressure, temperature and external magnetic field strength. Pressure and temperature dependence on nonlinear optical susceptibilities of generation of second and third order harmonics as a function of incident photon energy are brought out in the influence of magnetic field strength. The result shows that the electronic and nonlinear optical properties are significantly modified by the applications of external perturbations in a 9.0 1.0 6.0 4.0 GaAs P / GaAs P quantum dot.

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