Temperature effect on the magnetic-field-induced type-I→type-II transition in a CdTe/(Cd,Mn)Te superlattice

1991 ◽  
Vol 44 (20) ◽  
pp. 11302-11306 ◽  
Author(s):  
G. Peter ◽  
E. Deleporte ◽  
J. M. Berroir ◽  
C. Delalande ◽  
J. M. Hong ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Temperature Effect ◽  
Type I ◽  
Type Ii ◽  
The Magnetic Field

scholarly journals In-depth study of long-term variability in the X-ray emission of the Be/X-ray binary system AX J0049.4−7323

2018 ◽  
Vol 614 ◽  
pp. A34 ◽  
Author(s):  
L. Ducci ◽  
P. Romano ◽  
C. Malacaria ◽  
L. Ji ◽  
E. Bozzo ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Type I ◽  
Type Ii ◽  
X Ray ◽  
Upper Limit ◽  
Flux Variability ◽  
Depth Study ◽  
The Magnetic Field ◽  
Integral Data

AX J0049.4−7323 is a Be/X-ray binary in the Small Magellanic Cloud hosting a ~750 s pulsar which has been observed over the last ~17 years by several X-ray telescopes. Despite numerous observations, little is known about its X-ray behaviour. Therefore, we coherently analysed archival Swift, Chandra, XMM-Newton, RXTE, and INTEGRAL data, and we compared them with already published ASCA data, to study its X-ray long-term spectral and flux variability. AX J0049.4−7323 shows a high X-ray variability, spanning more than three orders of magnitudes, from L ≈ 1.6 × 1037 erg s−1 (0.3−8 keV, d = 62 kpc) down to L ≈ 8 × 1033 erg s−1. RXTE, Chandra, Swift, and ASCA observed, in addition to the expected enhancement of X-ray luminosity at periastron, flux variations by a factor of ~270 with peak luminosities of ≈2.1 × 1036 erg s−1 far from periastron. These properties are difficult to reconcile with the typical long-term variability of Be/XRBs, traditionally interpreted in terms of type I and type II outbursts. The study of AX J0049.4−7323 is complemented with a spectral analysis of Swift, Chandra, and XMM-Newton data which showed a softening trend when the emission becomes fainter, and an analysis of optical/UV data collected by the UVOT telescope on board Swift. In addition, we measured a secular spin-up rate of Ṗ = (−3.00 ± 0.12) × 10−3 s day−1, which suggests that the pulsar has not yet achieved its equilibrium period. Assuming spherical accretion, we estimated an upper limit for the magnetic field strength of the pulsar of ≈3 × 1012 G.

Studies of Ternary Nematic Phases by Nuclear Magnetic Resonance. Alkali Metal Decyl Sulfates/Decanol/D2O

1975 ◽  
Vol 53 (20) ◽  
pp. 2998-3004 ◽  
Author(s):  
Keith Radley ◽  
Leonard Wallace Reeves
Keyword(s):  
Magnetic Field ◽  
Alkali Metal ◽  
Nematic Phase ◽  
Ternary Phase Diagram ◽  
Phase Region ◽  
Coupling Constants ◽  
Type I ◽  
Type Ii ◽  
Nematic Phases ◽  
The Magnetic Field

The nematic regions of the ternary phase diagram for alkali metal decyl sulfates/decanol/D2O have been investigated. The lithium detergent system has a very restricted region of type I nematic phase which orients parallel to the magnetic field with a long time constant. The sodium detergent also forms a rather restricted nematic region which may be type II, oriented perpendicular to the magnetic field or type I oriented parallel to the magnetic field, depending on the decanol content. The rubidium and potassium detergents were insufficiently soluble to form phases while the cesium detergent forms a very extensive type II nematic phase region with wide variations in water contents and with decanol between 2 and 7 wt.%. It is clear that the cesium decyl sulfate system has considerable advantage over the sodium detergent in forming nematic phases for use as orienting media for small molecules and ions in n.m.r. studies.The partially averaged nuclear quadrupole coupling constants of Li-7, Na-23, and Cs-133 in ions and D-2 in the D2O have been used as the primary tool in investigating the phase behavior. Quadrupole couplings have been reduced to unit quadrupole moment for the nucleus. The resultant quantity "Es" in Hz b−1 reflects the strongly increasing electric field gradient induced in the monatomic ions by the nematic medium in going from Li+ to Cs+. The partially averaged quadrupole splittings which appear for the alkali metal ions in these uniaxial media are the result of distortion of the spherical symmetry of the ion and should not be interpreted in terms of degrees of orientation of the ion.

scholarly journals Analyzing the propagation of EUV waves and their connection with type II radio bursts by combining numerical simulations and multi-instrument observations

2020 ◽  
Vol 644 ◽  
pp. A90
Author(s):  
A. Koukras ◽  
C. Marqué ◽  
C. Downs ◽  
L. Dolla
Keyword(s):  
Magnetic Field ◽  
Wave Front ◽  
Ray Tracing ◽  
Radio Burst ◽  
Radio Bursts ◽  
Type Ii ◽  
Fast Mode ◽  
Type Ii Radio Bursts ◽  
The Magnetic Field ◽  
Burst Emission

Context. EUV (EIT) waves are wavelike disturbances of enhanced extreme ultraviolet (EUV) emission that propagate away from an eruptive active region across the solar disk. Recent years have seen much debate over their nature, with three main interpretations: the fast-mode magneto-hydrodynamic (MHD) wave, the apparent wave (reconfiguration of the magnetic field), and the hybrid wave (combination of the previous two). Aims. By studying the kinematics of EUV waves and their connection with type II radio bursts, we aim to examine the capability of the fast-mode interpretation to explain the observations, and to constrain the source locations of the type II radio burst emission. Methods. We propagate a fast-mode MHD wave numerically using a ray-tracing method and the WKB (Wentzel-Kramers-Brillouin) approximation. The wave is propagated in a static corona output by a global 3D MHD Coronal Model, which provides density, temperature, and Alfvén speed in the undisturbed coronal medium (before the eruption). We then compare the propagation of the computed wave front with the observed wave in EUV images (PROBA2/SWAP, SDO/AIA). Lastly, we use the frequency drift of the type II radio bursts to track the propagating shock wave, compare it with the simulated wave front at the same instant, and identify the wave vectors that best match the plasma density deduced from the radio emission. We apply this methodology for two EUV waves observed during SOL2017-04-03T14:20:00 and SOL2017-09-12T07:25:00. Results. The simulated wave front displays a good qualitative match with the observations for both events. Type II radio burst emission sources are tracked on the wave front all along its propagation. The wave vectors at the ray-path points that are characterized as sources of the type II radio burst emission are quasi-perpendicular to the magnetic field. Conclusions. We show that a simple ray-tracing model of the EUV wave is able to reproduce the observations and to provide insight into the physics of such waves. We provide supporting evidence that they are likely fast-mode MHD waves. We also narrow down the source region of the radio burst emission and show that different parts of the wave front are responsible for the type II radio burst emission at different times of the eruptive event.

Liquid crystal/glass interface effects on the orientation of lyotropic liquid crystals in magnetic fields

1978 ◽  
Vol 56 (16) ◽  
pp. 2178-2183 ◽  
Author(s):  
Fred Y. Fujiwara ◽  
Leonard W. Reeves
Keyword(s):  
Magnetic Field ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Cylindrical Tube ◽  
Lyotropic Liquid Crystals ◽  
Crystal Glass ◽  
Type I ◽  
Type Ii ◽  
Glass Interface ◽  
Interface Effects

Lyotropic mesophases of both positive (type I) and negative (type II) diamagnetic anisotropy have been prepared. The deuterium magnetic resonance signal from D2O in the sample bas been studied during the process of orientation in a magnetic field. A type II mesophase oriented by a magnetic field in a cylindrical tube perpendicular to the lines of force does not achieve a uniform distribution of directors in a plane perpendicular to the field. The re orientation of a type I mesophase after an initial displacement of the director at an angle to the field has been studied. Previous equations derived for thermotropic liquid crystals are applicable but the velocity of re-orientation was found to be an inverse function of the radius, for nmr tubes of less than 4 mm in diameter, indicating that liquid crystal/glass interface effects are important.

scholarly journals BIANCHI TYPE I MAGNETOFLUID COSMOLOGICAL MODELS WITH VARIABLE COSMOLOGICAL CONSTANT REVISITED

2004 ◽  
Vol 13 (03) ◽  
pp. 503-516 ◽  
Author(s):  
ANIRUDH PRADHAN ◽  
SANJAY KUMAR SINGH
Keyword(s):  
Magnetic Field ◽  
Bianchi Type ◽  
Mass Density ◽  
Type I ◽  
Variable Cosmological Constant ◽  
Bianchi Type I ◽  
Bulk Viscous ◽  
Tensor Formula ◽  
The Magnetic Field ◽  
Shear Tensor

The behaviour of magnetic field in anisotropic Bianchi type I cosmological model for bulk viscous distribution is investigated. The distribution consists of an electrically neutral viscous fluid with an infinite electrical conductivity. It is assumed that the component [Formula: see text] of shear tensor [Formula: see text] is proportional to expansion (θ) and the coefficient of bulk viscosity is assumed to be a power function of mass density. Some physical and geometrical aspects of the models are also discussed in presence and also in absence of the magnetic field.

Magnetic field-induced type I → type II transition in a semimagnetic superlattice

1990 ◽  
Vol 8 (2) ◽  
pp. 171-174 ◽  
Author(s):  
E. Deleporte ◽  
J.M. Berroir ◽  
G. Bastard ◽  
C. Delalande ◽  
J.M. Hong ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Type I ◽  
Type Ii

Shock Drift Acceleration and Type II Solar Radio Bursts

1994 ◽  
Vol 11 (1) ◽  
pp. 21-24 ◽  
Author(s):  
Arthur G. Street ◽  
Lewis Ball ◽  
D. B. Melrose
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Shock Front ◽  
Solar Radio ◽  
Radio Bursts ◽  
Type Ii ◽  
Solar Radio Bursts ◽  
Type Ii Bursts ◽  
Herringbone Structure ◽  
The Magnetic Field

AbstractShock drift acceleration of the electrons which produce herringbone structure in type II bursts is considered. A non-coplanar component of the magnetic field within the shock front and an electric field across the shock are taken into account. A quantitative difficulty with shock drift acceleration is identified, and possible ways of overcoming the difficulty are outlined.

SOME BIANCHI TYPE-II COSMOLOGICAL MODELS IN LYRA GEOMETRY

2010 ◽  
Vol 25 (12) ◽  
pp. 2525-2533 ◽  
Author(s):  
J. K. SINGH ◽  
N. K. SHARMA
Keyword(s):  
Magnetic Field ◽  
Bianchi Type ◽  
Lyra Geometry ◽  
Cosmological Models ◽  
Type Ii ◽  
Anisotropic Cosmological Models ◽  
Normal Gauge ◽  
Lyra’S Geometry ◽  
Presence And Absence ◽  
The Magnetic Field

In this work, we have studied the Bianchi type-II anisotropic cosmological models in the theory based on Lyra's geometry in normal gauge in the presence and absence of the magnetic field. The physical and kinematical behaviors of the models have also been discussed.

Sign in / Sign up

Export Citation Format

Share Document