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 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 Hot-star wind models with magnetically split line blanketing

2018 ◽  
Vol 620 ◽  
pp. A176 ◽  
Author(s):  
J. Krtička
Keyword(s):  
Magnetic Fields ◽  
Zeeman Effect ◽  
Zeeman Splitting ◽  
Magnetic Line ◽  
Hot Stars ◽  
Strong Magnetic Fields ◽  
Flux Variability ◽  
Line Splitting ◽  
Line Force ◽  
The Magnetic Field

Fraction of hot stars posses strong magnetic fields that channel their radiatively driven outflows. We study the influence of line splitting in the magnetic field (Zeeman effect) on the wind properties. We use our own global wind code with radiative transfer in the comoving frame to understand the influence of the Zeeman splitting on the line force. We show that the Zeeman splitting has a negligible influence on the line force for magnetic fields that are weaker than about 100 kG. This means that the wind mass-loss rates and terminal velocities are not affected by the magnetic line splitting for magnetic fields as are typically found on the surface of nondegenerate stars. Neither have we found any strong flux variability that would be due to the magnetically split line blanketing.

scholarly journals The Zeeman effect in strong magnetic fields

1925 ◽  
Vol 109 (749) ◽  
pp. 224-239 ◽  
Keyword(s):  
Magnetic Fields ◽  
General Principle ◽  
Small Volume ◽  
Zeeman Effect ◽  
Strong Magnetic Fields ◽  
Large Current ◽  
Accumulator Battery ◽  
The Subject ◽  
Short Time

From the time of Zeeman’s discovery, the Zeeman effect has been the subject of a large amount of work; but hitherto experiments have been limited by the fields obtainable with an electro-magnet. It is known that the strongest field which can be obtained with the largest practicable electro-magnet is about 80,000 gauss. On account of the necessity in Zeeman effect experiments for uniformity of the field over a considerable volume, no experiments seem to have been performed in fields stronger than 40 or 50,000 gauss. In a recent paper a method has been described by which considerably stronger fields may be produced. The general principle is to obtain the field by passing a large current through a coil (without iron) for a very short time; so that the coil has no time to heat up. The current is produced by short-circuiting a specially constructed accumulator battery through the coil, and in this way it is possible to use a power of 1,000 k. w. A field of strength up to 500 k. g. may be obtained in a very small volume; but for the study of the Zeeman effect, it has only been found possible to use fields of strength up to 130,000 gauss, since we must have the field uniform over a reasonable volume in which to place our source of light.

scholarly journals 19. Astrophysical applications of selective magnetic rotation

1958 ◽  
Vol 6 ◽  
pp. 166-168
Author(s):  
Y. öhman
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Zeeman Effect ◽  
Emission Lines ◽  
Absorption Lines ◽  
Magnetic Rotation ◽  
Double Refraction ◽  
Line Absorption ◽  
Complicated Process ◽  
The Magnetic Field

When measuring the magnetic fields of sunspots the astronomer assumes that the magnetic field revealed by the inverse Zeeman effect is the same as if the splitting were produced by emission lines instead of absorption lines. No doubt this is in general a very fair approximation, but we have reason to remember sometimes that line absorption in the presence of magnetic fields is a very complicated process. In the immediate neighbourhood of absorption lines effects of magnetic rotation of the plane of polarization and magnetic double refraction may appear in the spectrum.

scholarly journals Oscillatory convection in strong magnetic fields and origin of active regions

1968 ◽  
Vol 35 ◽  
pp. 127-130 ◽  
Author(s):  
S. I. Syrovatsky ◽  
Y. D. Zhugzhda
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Active Regions ◽  
Oscillatory Convection ◽  
Strong Magnetic Fields ◽  
Various Boundary Conditions ◽  
Convective Cells ◽  
The Magnetic Field ◽  
Polytropic Atmosphere

The convection in a compressible inhomogeneous conducting fluid in the presence of a vertical uniform magnetic field has been studied. It is shown that a new mode of oscillatory convection occurs, which exists in arbitrarily strong magnetic fields. The convective cells are stretched along the magnetic field, their horizontal dimensions are determined by radiative cooling. Criteria for convective instability in a polytropic atmosphere are obtained for various boundary conditions in the case when the Alfvén velocity is higher compared with the velocity of sound.The role of oscillatory convection in the origin of sunspots and active regions is discussed.

scholarly journals Open charm and charmonium states in strong magnetic fields

2021 ◽  
pp. 2150064
Author(s):  
Amruta Mishra ◽  
S. P. Misra
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Constituent Quark ◽  
Open Charm ◽  
Charm Mesons ◽  
Strong Magnetic Fields ◽  
Decay Widths ◽  
State Formula ◽  
The Masses ◽  
The Magnetic Field

The mass modifications of the open charm ([Formula: see text] and [Formula: see text]) mesons, and their effects on the decay widths [Formula: see text] as well as of the charmonium state, [Formula: see text] to open charm mesons ([Formula: see text]), are investigated in the presence of strong magnetic fields. These are studied accounting for the mixing of the pseudoscalar ([Formula: see text]) and vector ([Formula: see text]) mesons ([Formula: see text], [Formula: see text] mixings), with the mixing parameter, [Formula: see text] of a phenomenological three-point ([Formula: see text]) vertex interaction determined from the observed radiative decay width of [Formula: see text]. For charged [Formula: see text] mixing, this parameter is dependent on the magnetic field, because of the Landau level contributions to the vacuum masses of these mesons. The masses of the charged [Formula: see text] and [Formula: see text] mesons modified due to [Formula: see text] mixing, in addition, have contributions from the lowest Landau levels in the presence of a strong magnetic field. The effects of the magnetic field on the decay widths are studied using a field theoretical model of composite hadrons with quark (and antiquark) constituents. The matrix elements for these decays are evaluated using the light quark–antiquark pair creation term of the free Dirac Hamiltonian for the constituent quark field, with explicit constructions for the charmonium state [Formula: see text], the open charm ([Formula: see text], [Formula: see text], [Formula: see text]) mesons and the pion states in terms of the constituent quark fields. The parameter for the charged [Formula: see text] mixing is observed to increase appreciably with increase in the magnetic field. This leads to dominant modifications to their masses, and hence the decay widths of charged [Formula: see text] as well as [Formula: see text] at large values of the magnetic field. The modifications of the masses and decay widths of the open and hidden charm mesons in the presence of strong magnetic fields should have observable consequences on the production of the open charm ([Formula: see text] and [Formula: see text]) mesons as well as of the charmonium states resulting from noncentral ultra-relativistic heavy ion collision experiments.

scholarly journals Measurements of local magnetic fields in a solar flare by splitting of emissive peaks in cores of spectral lines

2018 ◽  
pp. 47-52 ◽  
Author(s):  
V. Lozitsky
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Solar Flare ◽  
Filling Factor ◽  
Spectral Lines ◽  
Local Fields ◽  
Strong Component ◽  
Component Structure ◽  
Local Magnetic Fields ◽  
The Magnetic Field

We present study of solar flare of 19 July 2000 which arose in active region NOAA 9087 and had M 5.6 / 3N importance. Observational material was obtained with the Echelle spectrograph of the horizontal solar telescope of the Astronomical Observatory of Taras Shevchenko National University of Kyiv. The local magnetic fields in this flare were measured by the splitting of emissive peaks of the FeI 5269.54, FeII 4923.93, Нα, Нβ, Нγand D3 HeI lines. The basic idea of the method is based on the fact that the flare emission in some spectral lines is clearly divided into two components: (1) wider and unpolarized, and (2) more narrow and polarized, with significant Zeeman splitting. This is indication to the two-component structure of the magnetic field, with substantially different magnetic fields and thermodynamical conditions in these two components. Due to the fact that the polarized emission is quite confidently separated from the unpolarized, it is possible to measure the local magnetic fields directly in the second (strong) component regardless of the filling factor. It was found that in the bright place of this flare, which was projected on the sunspot penumbra, the effective magnetic field Beff in the FeI 6301.5 i 6302.5 lines measured by splitting of the Fraunhofer profiles, was 900 G. However, the splitting of emissive peaks in Нα, Нβ, Нγ and D3 lines corresponds to 1000 G, 1400 G, 1450 G and about zero, respectively, with errors of 30-50 G for abovenamed FeI lines and about 100–150 G for other lines. This difference in the results is probably due to the fact that in the case of FeI 6301.5 i 6302.5 lines, the Beff value represents several parameters, including the value of the background field, the filling factor, and the intensity of the local fields in the strong component. In contrast, data on the Нα, Нβ, Нγ, and D3 lines mainly reflect local fields in the strong component and indicate the nonmonotonous distribution of the magnetic field with height in solar atmosphere, with its maximum at the chromospheric level. Earlier in this flare, when constructing its semi-empirical model, local amplification of the magnetic field at the photospheric level was discovered, and its value reached 1500 G. These data are confirmed by direct measurements of splitting of emissive peaks in FeI 5269.54 and FeII 4923.93 lines, according to which the magnetic field in the flare was 1250 ± 100 G. Thus, in this flare there were at least two regions (possibly two flat layers) of local amplification of the magnetic field.

scholarly journals Gravitational wave signatures of highly magnetized neutron stars

2020 ◽  
Vol 80 (12) ◽  
Author(s):  
Cesar V. Flores ◽  
Luiz L. Lopes ◽  
Luis B. Castro ◽  
Débora P. Menezes
Keyword(s):  
Magnetic Fields ◽  
Neutron Stars ◽  
Gravitational Wave ◽  
Field Approximation ◽  
Love Number ◽  
Strong Magnetic Fields ◽  
Chaotic Field ◽  
Quasi Normal Mode ◽  
Low Mass ◽  
The Magnetic Field

AbstractMotivated by the recent gravitational wave detection by the LIGO–VIRGO observatories, we study the Love number and dimensionless tidal polarizability of highly magnetized stars. We also investigate the fundamental quasi-normal mode of neutron stars subject to high magnetic fields. To perform our calculations we use the chaotic field approximation and consider both nucleonic and hyperonic stars. As far as the fundamental mode is concerned, we conclude that the role played by the constitution of the stars is far more relevant than the intensity of the magnetic field, and if massive stars are considered, the ones constituted by nucleons only present frequencies somewhat lower than the ones with hyperonic cores. This feature that can be used to point out the real internal structure of neutron stars. Moreover, our studies clearly indicate that strong magnetic fields play a crucial role in the deformability of low mass neutron stars, with possible consequences on the interpretation of the detected gravitational waves signatures.

scholarly journals Investigations of space magnetism at the Crimean Astrophysical Observatory. II. Direct spectropolarimetric measurements of stellar magnetic fields

2020 ◽  
Vol 1 (2) ◽  
pp. 26-36
Author(s):  
Sergei Plachinda ◽  
Varvara Butkovskaya
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Spectral Lines ◽  
Crimean Astrophysical Observatory ◽  
Scientific School ◽  
Pulsation Period ◽  
Echelle Spectrograph ◽  
Direct Measurements ◽  
Stellar Magnetic Fields ◽  
The Magnetic Field

A research on stellar magnetism in Crimea was initiated by pioneer works of A.B. Severny, V.E. Stepanov, and D.N. Rachkovsky. Today, the study of stellar magnetic fields is a key field of research at the Crimean Astrophysical Observatory (CrAO). The 2.6 m Shajn telescope equipped with the echelle spectrograph ESPL, CCD, and Stokesmeter (a circular polarization analyzer) allows us to study the magnetic field of bright stars up to 5m–6m. The Single Line (SL) technique is developed for measuring magnetic fields at CrAO. This technique is based on the calculation of the Zeeman effect in individual spectral lines. A key advantage of the SL technique is its ability to detect local magnetic fields on the surface of stars. Many results in the field of direct measurements of stellar magnetic fields were obtained at CrAO for the first time. In particular, the magnetic field on supergiants (ǫ Gem), as well as on a number of subgiants, giants, and bright giants was first detected. This, and investigations of other authors, confirmed the hypothesis that a magnetic field is generated at all the stages of evolution of late-type stars, including the stage of star formation. The emergence of large magnetic flux tubes at the surface of stars of V-IV-III luminosity classes (61 Cyg A, β Gem, β Aql) was first registered. In subgiants, the magnetic field behavior with the activity cycle was first established for β Aql. Using the long-term Crimean spectroscopic and spectropolarimetric observations of α Lyr, the 22-year variability cycle of the star, supposedly associated with meridional flows, is confirmed. Magnetic field variability with the pulsation period was first detected for different types of pulsating variables: the classical Cepheid β Aql, the low-amplitude β Cep-type variable γ Peg, and others. In this review we cover more than a half-century history of the formation of the Crimean scientific school for high-precision direct measurements of stellar magnetic fields.

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