scholarly journals Coupling of the magnetic field and gas flows inferred from the net circular polarization in a sunspot penumbra

2015 ◽  
Vol 67 (2) ◽  
Author(s):  
Abdelrazek M. K. Shaltout ◽  
Kiyoshi Ichimoto
Keyword(s):  
Magnetic Field ◽  
Circular Polarization ◽  
Gas Flows ◽  
The Magnetic Field ◽  
Sunspot Penumbra

scholarly journals Broadband Linear Polarization in Ap Stars

1993 ◽  
Vol 138 ◽  
pp. 305-309
Author(s):  
Marco Landolfi ◽  
Egidio Landi Degl’Innocenti ◽  
Maurizio Landi Degl’Innocenti ◽  
Jean-Louis Leroy ◽  
Stefano Bagnulo
Keyword(s):  
Magnetic Field ◽  
Circular Polarization ◽  
Linear Polarization ◽  
Rotation Axis ◽  
Spectral Lines ◽  
Line Of Sight ◽  
Long Time ◽  
Rotating Star ◽  
Ap Stars ◽  
The Magnetic Field

AbstractBroadband linear polarization in the spectra of Ap stars is believed to be due to differential saturation between σ and π Zeeman components in spectral lines. This mechanism has been known for a long time to be the main agent of a similar phenomenon observed in sunspots. Since this phenomenon has been carefully calibrated in the solar case, it can be confidently used to deduce the magnetic field of Ap stars.Given the magnetic configuration of a rotating star, it is possible to deduce the broadband polarization at any phase. Calculations performed for the oblique dipole model show that the resulting polarization diagrams are very sensitive to the values of i (the angle between the rotation axis and the line of sight) and β (the angle between the rotation and magnetic axes). The dependence on i and β is such that the four-fold ambiguity typical of the circular polarization observations ((i,β), (β,i), (π-i,π-β), (π-β,π-i)) can be removed.

Design of a local bump feedback system for a variably polarizing undulator

1998 ◽  
Vol 5 (3) ◽  
pp. 465-467 ◽  
Author(s):  
Teruhiko Bizen ◽  
Taihei Shimada ◽  
Masaru Takao ◽  
Yoichi Hiramatu ◽  
Yoshikazu Miyahara
Keyword(s):  
Magnetic Field ◽  
Circular Polarization ◽  
Feedback System ◽  
Beam Position ◽  
X Ray ◽  
Double Array ◽  
Under Construction ◽  
Polarization Of Light ◽  
Field Errors ◽  
The Magnetic Field

A local bump feedback system is under construction to correct the orbit distortion caused by the magnetic field errors of a double-array undulator used to generate linear and circular polarization of light for a soft X-ray beamline. The local bump orbit is created by steering coils several turns long and four sets of steering magnets. The kick angle of the long steering coils and the steering magnets is determined according to the motion of the undulator and by detecting the beam position.

Analysis and Experimental Study on Magnetic Fluid Seal Mechanism

2011 ◽  
Vol 492 ◽  
pp. 273-276 ◽  
Author(s):  
Hai Na Zhang ◽  
De Cai Li
Keyword(s):  
Magnetic Field ◽  
Experimental Study ◽  
Field Distribution ◽  
Magnetic Fluid ◽  
Magnetic Field Distribution ◽  
Gas Flows ◽  
Experimental Setup ◽  
Pressure Transmission ◽  
The Magnetic Field ◽  
The Way

The authors put forward a new design of experimental setup in order to study the mechanism of magnetic fluid seal, and used Ansys to simulate the magnetic field distribution in the setup, the results prove its rationality. The experiment to study the way of pressure transmission has been done on the experimental setup. The experimental conclusion shows that pressure transmission is based on the recoverability of the magnetic fluid seal. When pressure exceeds the ability of the seal stage, there is a leak path in the magnetic fluid, and then the gas flows to the next stage, after that, the leak path disappears. Pressure transmits from one seal stage to the next one in this way.

THE PARSEC-SCALE CIRCULAR POLARIZATION OF ACTIVE GALACTIC NUCLEI AT 22 AND 15 GHZ

2008 ◽  
Vol 17 (09) ◽  
pp. 1531-1535 ◽  
Author(s):  
V. M. VITRISHCHAK ◽  
D. C. GABUZDA
Keyword(s):  
Magnetic Field ◽  
Active Galactic Nuclei ◽  
Circular Polarization ◽  
Galactic Nuclei ◽  
Core Region ◽  
Field Orientation ◽  
Magnetic Field Orientation ◽  
Long Baseline ◽  
Very Long Baseline Array ◽  
The Magnetic Field

We present the results of parsec-scale circular polarization measurements based on Very Long Baseline Array data for a number of radio-bright, core-dominated active galactic nuclei obtained simultaneously at 22 and 15 GHz. The degrees of circular polarization mc for the VLBI core region at 15 GHz are similar to values reported earlier at this wavelength, with typical values of a few tenths of a percent. The origin of this polarization is almost certainly the conversion of linear to circular polarization during the propagation of the radiation through a magnetised plasma. We find that mc is as often higher as lower at the higher frequency, for reasons that are not clear. Our results confirm the earlier finding that the sign of the circular polarization at a given observing frequency is generally consistent across epochs separated by several years or more, suggesting stability of the magnetic field orientation in the innermost jets.

scholarly journals Polarization of the Recombination Line Maser in MWC349

2012 ◽  
Vol 8 (S287) ◽  
pp. 49-53 ◽  
Author(s):  
C. Thum ◽  
D. Morris ◽  
H. Wiesemeyer
Keyword(s):  
Magnetic Field ◽  
Circular Polarization ◽  
Time Variable ◽  
Circumstellar Disk ◽  
Recombination Line ◽  
Complex Time ◽  
Disk Dynamo ◽  
The Magnetic Field

AbstractWe present observations of the circular polarization of the recombination line maser in MWC 349. Six good quality Ha30α spectra were obtained during 2010 – 2011 which show that the Zeeman features are complex, time variable, and usually different for the blue- and red-shifted maser spikes. We propose that the magnetic field, located in the corona of the circumstellar disk, has toroidal and radial components. It is plausibly generated in a disk dynamo.

Application of the Dipole Model to Selected Magnetic White Dwarfs

1989 ◽  
Vol 8 (2) ◽  
pp. 148-153 ◽  
Author(s):  
N. Achilleos ◽  
D. T. Wickramasinghe
Keyword(s):  
Magnetic Field ◽  
Circular Polarization ◽  
Observational Data ◽  
White Dwarfs ◽  
Zeeman Splitting ◽  
Polarization Data ◽  
Detailed Model ◽  
Field Geometry ◽  
Hydrogen Lines ◽  
The Magnetic Field

AbstractVarious authors have reported observations of the flux and circular polarization for the three stars PG 1658 + 441, PG 1533 − 057 and K 813 − 14. On the basis of the observational data, the stars were classified as magnetic white dwarfs. To place constraints on the magnetic field strengths and geometries of these stars, the relevant authors qualitatively compared the data with available theory and, in two cases, used a model of optically thin hydrogen threaded by a magnetic field.In this paper we use a more detailed model for magnetic white dwarfs to assess the results previously obtained for these three stars. We find that, in two cases, the observed spectra can be explained by the Zeeman splitting of hydrogen lines in a stellar magnetic field which takes the form of a dipole situated at the centre of the star. The circular polarization data for PG 1658 + 441, however, may indicate a field geometry for this star which is significally different from that of a centred dipole.

scholarly journals RATAN-600 Observations of Unusual Inversion of Polarization in Sunspot Associated Microwave Sources

2005 ◽  
Vol 13 ◽  
pp. 137-137
Author(s):  
N. A. B. Gizani ◽  
C. Alissandrakis ◽  
V. Bogod ◽  
V. Garaimov ◽  
V. Zheleznyakov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Circular Polarization ◽  
Radio Telescope ◽  
The West ◽  
Bipolar Structure ◽  
High Polarization ◽  
West Limb ◽  
Microwave Sources ◽  
The Magnetic Field

We have discovered unusual inversion of circular polarization in both components of an active region. We have observed the region for six consecutive days in May 96 using the RATAN-600 radio telescope with high polarization accuracy up to 0.5 %. The observations were taken in the range of 1.7 to 30 cm. At short wavelengths the circular polarization scans revealed a bipolar structure, expected since the magnetic field is bipolar. However, for all six days and while the region was moving from the center of the disk to the west limb, the circular polarization dropped practically to zero at 14.5 cm and at longer wavelengths the sense of the polarization was reversed.

scholarly journals The magnetic field of the evolved star W43A

2008 ◽  
Vol 4 (S259) ◽  
pp. 109-110
Author(s):  
Nikta Amiri ◽  
Wouter Vlemmings ◽  
Huib Jan van Langevelde
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Circular Polarization ◽  
Magnetic Field Strength ◽  
Large Scale ◽  
Zeeman Splitting ◽  
Density Region ◽  
Evolved Stars ◽  
Large Scale Magnetic Field ◽  
The Magnetic Field

AbstractPlanetary nebulae (PNe) often show large departures from spherical symmetry. The origin and development of these asymmetries is not clearly understood. The most striking structures are the highly collimated jets that are already observed in a number of evolved stars before they enter the PN phase. The aim of this project is to observe the Zeeman splitting of the OH maser of the W43A star and determine the magnetic field strength in the low density region. The 1612 MHz OH masers of W43A were observed with MERLIN to measure the circular polarization due to the Zeeman splitting of 1612 OH masers in the envelope of the evolved star W43A. We measured the circular polarization of the strongest 1612 OH masers of W43A and found a magnetic field strength of ~100μG. The magnetic field measured at the location of W43A OH masers confirms that a large scale magnetic field is present in W43A, which likely plays a role in collimating the jet.

scholarly journals The Magnetic Field of the Milky Way

1990 ◽  
Vol 140 ◽  
pp. 29-34
Author(s):  
Virginia Trimble
Keyword(s):  
Magnetic Field ◽  
Interstellar Dust ◽  
Galactic Center ◽  
Zeeman Splitting ◽  
Gas Flows ◽  
Interstellar Dust Grains ◽  
Grand Design ◽  
Component Field ◽  
The Magnetic Field ◽  
Rule Out

Since its discovery 40 years ago as a confiner of cosmic rays and an aligner of interstellar dust grains, the Galactic magnetic field has been studied through emission and polarization of synchrotron radiation, Faraday rotation, Zeeman splitting, and effects on gas flows and morphology. The local field has a coherent, few microgauss, component roughly along the local spiral arm and a comparable chaotic component. Field direction in the plane is reversed one or more times both inside and outside the solar circle. Loops and spurs extend outside the plane and may merge with a general dipole, which is most conspicuous near the Galactic center. There may be a separate thick disc magneto-ionic component. Comparison with other galaxies, especially grand design vs. flocculent spirals should eventually prove fruitful. Parameters are not currently well enough known to rule out dipole or primordial origin.

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