scholarly journals On the Orientation of Magnetic Fields in Quiescent Prominences

1971 ◽  
Vol 43 ◽  
pp. 656-662 ◽  
Author(s):  
Ulrich Anzer ◽  
E. Tandberg-Hanssen
Keyword(s):  
Magnetic Field ◽  
Distribution Function ◽  
Zeeman Effect ◽  
General Rule ◽  
Longitudinal Component ◽  
Spectral Lines ◽  
The Other ◽  
Relative Importance ◽  
Quiescent Prominence ◽  
The Magnetic Field

The longitudinal component of the magnetic field in quiescent prominences has been measured directly with magnetographs using the Zeeman effect on selected spectral lines (Rust, 1966; Ioshpa, 1968; Harvey, 1969). We know that as a general rule the magnetic field enters the, largely-vertical, sheet-like quiescent prominence on one side and exits on the other. The field traverses the prominence plasma with components both along and at right angles to the long axis of the prominence. It is the purpose of this paper to describe observations that may indicate the relative importance of the two components of the magnetic field, and to derive a distribution function for the magnetic field vectors.

scholarly journals Observations of Magnetic Fields in Quiescent Prominences

1971 ◽  
Vol 43 ◽  
pp. 192-200 ◽  
Author(s):  
Einar Tandberg-Hanssen
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Field Component ◽  
Zeeman Effect ◽  
Mean Value ◽  
Longitudinal Component ◽  
The Other ◽  
Magnetic Field Component ◽  
The Magnetic Field

The longitudinal component of the magnetic field, B∥, has been recorded in about 135 quiescent prominences observed at Climax during the period 1968–1969. The measurements were obtained with the magnetograph which records the Zeeman effect on hydrogen, helium and metal lines. The following lines were used, Hα; He I, D3, He I, 4471 Å; Na I, D1 and D2, and the observed magnetic field component in these prominences was independent of the line. The overall mean value of the field B∥ for all the prominences was 7.3G. As a rule, the magnetic field enters the prominence on one side and exits on the other, but in traversing the prominence material, the field tends to run along the long axis of the prominence.

scholarly journals Magnetic fields of rapidly oscillating Ap stars

1993 ◽  
Vol 139 ◽  
pp. 132-132
Author(s):  
G. Mathys
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Magnetic Fields ◽  
Zeeman Effect ◽  
Rotation Frequency ◽  
Spectral Lines ◽  
Driving Mechanism ◽  
Line Splitting ◽  
Ap Stars ◽  
The Magnetic Field

Magnetic field appears to play a major role in the pulsations of rapidly oscillating Ap (roAp) stars. Understanding of the behaviour of these objects thus requires knowledge of their magnetic field. Such knowledge is in particular essential to interpret the modulation of the amplitude of the photometric variations (with a frequency very close to the rotation frequency of the star) and to understand the driving mechanism of the pulsation. Therefore, a systematic programme of study of the magnetic field of roAp stars has been started, of which preliminary (and still very partial) results are presented here.Magnetic fields of Ap stars can be diagnosed from the Zeeman effect that they induced in spectral lines either from the observation of line-splitting in high-resolution unpolarized spectra (which only occurs in favourable circumstances) or from the observation of circular polarization of the lines in medium- to high-resolution spectra.

scholarly journals Structure in the gas and magnetic field in S106

1991 ◽  
Vol 147 ◽  
pp. 61-64
Author(s):  
Richard M. Crutcher
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Massive Star ◽  
Zeeman Effect ◽  
The Other ◽  
Molecular Line ◽  
Show Evidence ◽  
The Magnetic Field

BIMA molecular-line observations show evidence for an expanding molecular ring around IRS 4, a newly formed massive star at the center of the bipolar nebula S106. VLA observations of the Zeeman effect in the OH 1665 MHz line show that the magnetic field strength is about 1 mG and that it reverses direction from one lobe of the bipolar nebula to the other.

scholarly journals Discovery of six new strongly magnetic white dwarfs in the 20 pc local population

2020 ◽  
Vol 643 ◽  
pp. A134 ◽  
Author(s):  
Stefano Bagnulo ◽  
John D. Landstreet
Keyword(s):  
Magnetic Field ◽  
White Dwarfs ◽  
Local Population ◽  
Longitudinal Component ◽  
Spectral Lines ◽  
Total Production ◽  
Milky Way Galaxy ◽  
Circular Polarisation ◽  
Cool White Dwarfs ◽  
The Magnetic Field

The sample of white dwarfs included in the local 20 pc volume documents, fairly accurately, the total production of white dwarfs over roughly 10 Gyr of stellar evolution in this part of the Milky Way Galaxy. In this sample, we have been systematically searching for magnetic white dwarfs. Here we report the discovery of six new magnetic white dwarfs, with a field strength from a few MG to about 200 MG. Two of these stars show H lines that are split and polarised by the magnetic field. One star shows extremely weak spectral lines in intensity, to which highly polarised narrow features correspond. The three other stars have featureless flux spectra, but show continuum polarisation. These new discoveries support the view that at least 20% of all white dwarfs in the local 20 pc volume have magnetic fields, and they fully confirm the suspicion that magnetism is a common rather than a rare characteristic of white dwarfs. We discuss the level and the handedness of the continuum polarisation in the presence of a magnetic field in cool white dwarfs. We suggest that a magnetic field with a 15 MG longitudinal component produces 1% of continuum circular polarisation. We have also shown that the problem of cross-talk from linear to circular polarisation of the FORS2 instrument, used in our survey, represents an obstacle to accurate measurements of the circular polarisation of faint white dwarfs when the background is illuminated, and polarised, by the moon.

scholarly journals The magnetic field of the Galaxy determined from the zeeman splitting of the 21-cm hydrogen line

1964 ◽  
Vol 20 ◽  
pp. 134-139
Author(s):  
R. D. Davies
Keyword(s):  
Magnetic Field ◽  
Zeeman Effect ◽  
Mean Field ◽  
Neutral Hydrogen ◽  
Zeeman Splitting ◽  
Longitudinal Component ◽  
Frequency Separation ◽  
Intensity Difference ◽  
Interstellar Clouds ◽  
The Magnetic Field

The Zeeman effect can be used to measure directly the longitudinal component of the magnetic field in interstellar neutral hydrogen clouds. The frequency separation between the two circularly polarized components is 28 c/s for 10–5 G and can be inferred from measurements of the intensity difference between left- and right-hand circular polarization as a function of frequency. Earlier experiments at Jodrell Bank showed that the mean field in the interstellar medium was less than 10–5 G (Davies et al. 1960). Recent work using more sensitive techniques has provided a positive measurement of a weak general magnetic field and of fields of varying intensity in different interstellar clouds.

scholarly journals Structure in the gas and magnetic field in S106

1991 ◽  
Vol 147 ◽  
pp. 61-64
Author(s):  
Richard M. Crutcher
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Massive Star ◽  
Zeeman Effect ◽  
The Other ◽  
Molecular Line ◽  
Show Evidence ◽  
The Magnetic Field

BIMA molecular-line observations show evidence for an expanding molecular ring around IRS 4, a newly formed massive star at the center of the bipolar nebula S106. VLA observations of the Zeeman effect in the OH 1665 MHz line show that the magnetic field strength is about 1 mG and that it reverses direction from one lobe of the bipolar nebula to the other.

Magnetic Field Spectroheliograms from the San Fernando Observatory

1971 ◽  
Vol 43 ◽  
pp. 329-339 ◽  
Author(s):  
Dale Vrabec
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Spiral Structure ◽  
Longitudinal Component ◽  
Solar Telescope ◽  
Solar Magnetic Fields ◽  
San Fernando ◽  
Field Lines ◽  
The Magnetic Field ◽  
Field Network

Zeeman spectroheliograms of photospheric magnetic fields (longitudinal component) in the CaI 6102.7 Å line are being obtained with the new 61-cm vacuum solar telescope and spectroheliograph, using the Leighton technique. The structure of the magnetic field network appears identical to the bright photospheric network visible in the cores of many Fraunhofer lines and in CN spectroheliograms, with the exception that polarities are distinguished. This supports the evolving concept that solar magnetic fields outside of sunspots exist in small concentrations of essentially vertically oriented field, roughly clumped to form a network imbedded in the otherwise field-free photosphere. A timelapse spectroheliogram movie sequence spanning 6 hr revealed changes in the magnetic fields, including a systematic outward streaming of small magnetic knots of both polarities within annular areas surrounding several sunspots. The photospheric magnetic fields and a series of filtergrams taken at various wavelengths in the Hα profile starting in the far wing are intercompared in an effort to demonstrate that the dark strands of arch filament systems (AFS) and fibrils map magnetic field lines in the chromosphere. An example of an active region in which the magnetic fields assume a distinct spiral structure is presented.

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.

scholarly journals THE ENERGY EIGENVALUES OF THE TWO DIMENSIONAL HYDROGEN ATOM IN A MAGNETIC FIELD

2006 ◽  
Vol 15 (06) ◽  
pp. 1263-1271 ◽  
Author(s):  
A. SOYLU ◽  
O. BAYRAK ◽  
I. BOZTOSUN
Keyword(s):  
Magnetic Field ◽  
Hydrogen Atom ◽  
Iteration Method ◽  
Weak Magnetic Field ◽  
The Other ◽  
Asymptotic Iteration Method ◽  
Iterative Approach ◽  
Two Dimensional ◽  
Energy Eigenvalues ◽  
The Magnetic Field

In this paper, the energy eigenvalues of the two dimensional hydrogen atom are presented for the arbitrary Larmor frequencies by using the asymptotic iteration method. We first show the energy eigenvalues for the case with no magnetic field analytically, and then we obtain the energy eigenvalues for the strong and weak magnetic field cases within an iterative approach for n=2-10 and m=0-1 states for several different arbitrary Larmor frequencies. The effect of the magnetic field on the energy eigenvalues is determined precisely. The results are in excellent agreement with the findings of the other methods and our method works for the cases where the others fail.

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