scholarly journals Zeeman effects for fine structure components of thallium spectral lines

1930 ◽  
Vol 129 (809) ◽  
pp. 48-70 ◽  
Keyword(s):  
Fine Structure ◽  
Magnetic Fields ◽  
Atomic Structure ◽  
Zeeman Effect ◽  
Spectral Lines ◽  
Correct Classification ◽  
Vector Coupling ◽  
Atomic Nuclei ◽  
Extensive Analysis ◽  
Quantum Vector

For many years the study of the Zeeman effect with various types of spectra lines has been a very successful method of investigating the electronic features of atomic structure. More recently it has proved to be a successful means of investigating some of the characteristics of atomic nuclei. Certain considerations now being brought forward, associate the fine structure of spectral lines with the spin of the nuclei of the atoms in which the radiation originates. As spectral lines with fine structure components having separations of a considerable magnitude have been found in the spectra of thallium and other elements, it is evident that in a study of the Zeeman effects for these components with magnetic fields of various strengths, a very promising filed of investigation has been created. In the investigation top be described initially to securing Zeeman effects for certain prominent lines in the spark spectrum of thallium in order to obtain information which would lead to their correct classification. While this work was in progress, other investigators, utilising the information at hand concerning the spectra of Hg I and Pb III, were able to assign classifications to a few of the wave-lengths of thallium II in question. These results are now embodied in the publication of a more extensive analysis by McLennan, McLay and Crawford ( loc. cit .). It was thought well, however, to continue the Zeeman effect investigation having in mind either the confirmation of their classification or the extension of the information available regarding the Zeeman effect with elements of high atomic number. In general, the spectra of such atoms indicate interesting quantum vector coupling types.

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 Magnetic Fields Measured with the 10830 Å HeI Line

1971 ◽  
Vol 43 ◽  
pp. 279-288 ◽  
Author(s):  
J. Harvey ◽  
D. Hall
Keyword(s):  
Fine Structure ◽  
Magnetic Fields ◽  
Near Infrared ◽  
Active Regions ◽  
Field Measurements ◽  
Spectral Lines ◽  
Magnetic Field Measurements ◽  
Infrared Spectral ◽  
Polarity Reversals ◽  
Absorption Features

Several advantages of near infrared spectral lines for magnetic field measurements are listed. In particular, the 10830 Å multiplet of HeI is well suited for observations of chromospheric magnetic fields.New photoelectric spectroheliograms made with the 10830 Å line reveal a large amount of filamentary fine structure in active regions. This fine structure has important consequences on the interpretation of 10830 Å magnetograms. Except for an association of 10830 Å disk filaments with polarity reversals there is little correlation between absorption features and the 10830 Å longitudinal field. Comparisons of chromospheric and photospheric observations show that the chromospheric field is spatially more diffuse and weaker than the photospheric field.

scholarly journals roAp stars

1995 ◽  
Vol 10 ◽  
pp. 338-340
Author(s):  
D. Kurtz ◽  
P. Martinez
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Rotation Axis ◽  
Zeeman Effect ◽  
Spectral Lines ◽  
Effective Magnetic Field ◽  
Surface Magnetic Field ◽  
Ap Stars

Among the A stars there is a subclass of peculiar stars, the Ap stars, which show strongly enhanced spectral lines of the Fe peak, rare earth and lanthanide elements. These stars have global surface magnetic fields several orders of magnitude larger than that of the Sun, 0.3 to 30 kGauss is the measured range. For stars with the strongest magnetic fields, the spectral lines are split by the Zeeman Effect and the surface magnetic field strength can be measured. Generally, though, the magnetic fields are not strong enough for the magnetic splitting to exceed other sources of line broadening. In these cases residual polarization differences between the red and blue wings of the spectral lines give a measure of the effective magnetic field strength - the integral of the longitudinal component of the global magnetic field over the visible hemisphere, weighted by limb-darkening. In the Ap stars the effective magnetic field strengths vary with rotation. This is well understood in terms of the oblique rotator model in which the magnetic axis is oblique to the rotation axis, so that the magnetic field is seen from varying aspect with rotation.

scholarly journals Coronal Magnetic Fields

1986 ◽  
Vol 7 ◽  
pp. 447-456
Author(s):  
R. Pallavicini
Keyword(s):  
Magnetic Fields ◽  
Transition Region ◽  
Solar Physics ◽  
Zeeman Effect ◽  
Spectral Lines ◽  
The Sun ◽  
Direct Measurements ◽  
Future Space ◽  
Coronal Magnetic Fields ◽  
Polarization Characteristics

It is unfortunate that coronal magnetic fields cannot be easily measured, even in the case of the Sun. Except for a few measurements of magnetic fields in the transition region above sunspots, made using the conventional Zeeman effect, and except for the possibility of inferring the direction – not the intensity – of coronal magnetic fields using optical forbidden lines, direct measurements of coronal fields are virtually non-existent. The most promising method appears to be the use of the Hanle effect, i.e. the modification of polarization characteristics of spectral lines induced by magnetic fields. This method has been proposed for future space missions in solar physics, for instance for the European satellite SOHO, but its feasibility depends on the strength of the fields to be measured, which in any case must be higher than a few tens of Gauss.

scholarly journals Diagnostic methods based on scattering polarization and the joint action of the Hanle and Zeeman effects

2008 ◽  
Vol 4 (S259) ◽  
pp. 623-632
Author(s):  
Javier Trujillo Bueno
Keyword(s):  
Magnetic Fields ◽  
Solar Physics ◽  
Energy Levels ◽  
Zeeman Effect ◽  
Polarized Light ◽  
Thomson Scattering ◽  
Stellar Atmospheres ◽  
Diagnostic Methods ◽  
Spectral Lines ◽  
Polarized Radiation

AbstractPolarized light provides the most reliable source of information at our disposal for diagnosing the physical properties of astrophysical plasmas, including the magnetic fields of the solar atmosphere. The interaction between radiation and hydrogen plus free electrons through Rayleigh and Thomson scattering gives rise to the polarization of the stellar continuous spectrum, which is very sensitive to the medium's thermal and density structure. Anisotropic radiative pumping processes induce population imbalances and quantum coherences among the sublevels of degenerate energy levels (that is, atomic level polarization), which produce polarization in spectral lines without the need of a magnetic field. The Hanle effect caused by the presence of relatively weak magnetic fields modifies the atomic polarization of the upper and lower levels of the spectral lines under consideration, allowing us to detect magnetic fields to which the Zeeman effect is blind. After discussing the physical origin of the polarized radiation in stellar atmospheres, this paper highlights some recent developments in polarized radiation diagnostic methods and a few examples of their application in solar physics.

scholarly journals The Zeeman and Paschen-Back effects in strong magnetic fields

1938 ◽  
Vol 167 (928) ◽  
pp. 1-15 ◽  
Author(s):  
Piotr Leonidovich Kapitza ◽  
P. G. Strelkov ◽  
E. Laurman
Keyword(s):  
Magnetic Fields ◽  
Experimental Error ◽  
Applied Field ◽  
Zeeman Effect ◽  
Spectral Lines ◽  
Strong Magnetic Fields ◽  
Current Impulse ◽  
Accumulator Battery ◽  
Small Capacity ◽  
The Magnetic Field

The Zeeman effect in strong magnetic fields was first studied by Kapitza and Skinner (1925), the fields being obtained by a method developed by one of us (Kapitza 1924), in which an accumulator battery of small capacity was discharged through a coil. In this way it was possible to obtain magnetic fields up to 140,000 gauss during a time of 1/100 sec. It turned out that in such fields the majority of the spectral lines which were studied, split up (within the limits of experimental error) proportionally to the applied field, in accordance with the theory which had previously been verified only in weaker magnetic fields. An exception, however, was the zinc line at 4680 A, which gave a splitting about 10% greater than that predicted by the theory, this discrepancy being outside the limits of experimental error. Since then the method of producing strong magnetic fields has been considerably developed (Kapitza 1927); instead of the discharge of an accumulator the powerful current impulse from a short-circuited generator has been used, which has made possible the production of fields more than twice as great as those formerly obtained, and moreover, in considerably larger volumes. A the same time the technique of measuring the magnetic field has also been improved. Using these improvements we have made a new investigation of the Zeeman effect in fields up to 320,000 gauss, in which we have been able to increase considerably the accuracy of the measurements, and to explain the cause of the discrepancies previously found. We have also been able to investigate the Paschen-Back effect and to verify the theory of this effect.

scholarly journals Hidden magnetic fields of young suns

2020 ◽  
Vol 635 ◽  
pp. A142 ◽  
Author(s):  
O. Kochukhov ◽  
T. Hackman ◽  
J. J. Lehtinen ◽  
A. Wehrhahn
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Field Strength ◽  
Zeeman Effect ◽  
Spectral Lines ◽  
Doppler Imaging ◽  
Field Energy ◽  
Small Scale ◽  
Clear Correlation ◽  
Surface Magnetic Field

Global magnetic fields of active solar-like stars are, nowadays, routinely detected with spectropolarimetric measurements and are mapped with Zeeman Doppler imaging (ZDI). However, due to the cancellation of opposite field polarities, polarimetry only captures a tiny fraction of the magnetic flux and cannot assess the overall stellar surface magnetic field if it is dominated by a small-scale component. The analysis of Zeeman broadening in high-resolution intensity spectra can reveal these hidden complex magnetic fields. Historically, there were very few attempts to obtain such measurements for G dwarf stars due to the difficulty of disentangling the Zeeman effect from other broadening mechanisms affecting spectral lines. Here, we developed a new magnetic field diagnostic method based on relative Zeeman intensification of optical atomic lines with different magnetic sensitivity. By using this technique, we obtained 78 field strength measurements for 15 Sun-like stars, including some of the best-studied young solar twins. We find that the average magnetic field strength Bf drops from 1.3−2.0 kG in stars younger than about 120 Myr to 0.2−0.8 kG in older stars. The mean field strength shows a clear correlation with the Rossby number and with the coronal and chromospheric emission indicators. Our results suggest that magnetic regions have roughly the same local field strength B ≈ 3.2 kG in all stars, with the filling factor f of these regions systematically increasing with stellar activity. In comparing our results with the spectropolarimetric analyses of global magnetic fields in the same stars, we find that ZDI recovers about 1% of the total magnetic field energy in the most active stars. This figure drops to just 0.01% for the least active targets.

scholarly journals VLA Mapping of Magnetic Fields in W 3 and S 106

1990 ◽  
Vol 140 ◽  
pp. 315-317
Author(s):  
R. M. Crutcher
Keyword(s):  
Star Formation ◽  
Magnetic Fields ◽  
Formation Process ◽  
Preliminary Report ◽  
Massive Star ◽  
High Spatial Resolution ◽  
Zeeman Effect ◽  
Spectral Lines ◽  
Interstellar Clouds ◽  
H Ii Region

The importance of magnetic fields to the evolution of dense interstellar clouds and to the star formation process is now widely appreciated. Troland (this volume) has reviewed work to measure strengths of interstellar magnetic fields by observation of the Zeeman effect in radio frequency spectral lines. The next step is to map magnetic fields with radio synthesis arrays in order to obtain high spatial resolution. This abstract is a preliminary report of VIA results for two clouds - the W 3 region of massive star formation (to be published by Troland, Crutcher, Goss, and Heiles) and S 106, a biconical H II region with a confining molecular disk (to be published by Loushin, Crutcher, and Troland).

The Interpretation of Line Profiles

1977 ◽  
Vol 36 ◽  
pp. 191-215
Author(s):  
G.B. Rybicki
Keyword(s):  
Magnetic Fields ◽  
Atomic Physics ◽  
Velocity Fields ◽  
Spectral Lines ◽  
Inhomogeneous Structure ◽  
The Sun ◽  
Line Profiles ◽  
Physical Phenomena

Observations of the shapes and intensities of spectral lines provide a bounty of information about the outer layers of the sun. In order to utilize this information, however, one is faced with a seemingly monumental task. The sun’s chromosphere and corona are extremely complex, and the underlying physical phenomena are far from being understood. Velocity fields, magnetic fields, Inhomogeneous structure, hydromagnetic phenomena – these are some of the complications that must be faced. Other uncertainties involve the atomic physics upon which all of the deductions depend.

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