scholarly journals Detection of magnetic fields in He-rich early B-type stars using HARPSpol

2018 ◽  
Vol 618 ◽  
pp. L2 ◽  
Author(s):  
S. P. Järvinen ◽  
S. Hubrig ◽  
I. Ilyin ◽  
M. Schöller ◽  
M. F. Nieva ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Longitudinal Magnetic Field ◽  
High Accuracy ◽  
Photometric Data ◽  
The Other ◽  
High Spectral Resolution ◽  
Periodic Modulation ◽  
First Time ◽  
The Magnetic Field

Aims. We focus on early-B type stars with helium overabundance, for which the presence of a magnetic field has not previously been reported. Methods. The measurements were carried out using high-spectral-resolution spectropolarimetric observations obtained with the High Accuracy Radial velocity Planet Searcher (HARPS) in polarimetric mode, installed at the ESO La Silla 3.6 m telescope. Results. For five He-rich stars, the longitudinal magnetic field was detected for the first time. For one target, HD 58260, the presence of a longitudinal magnetic field of the order of 1.8 kG has already been reported in the literature, but the magnetic field has remained constant over tens of years. Our measurement carried out using the polarimetric spectra obtained in 2015 March indicates a slight decrease of the longitudinal magnetic field strength compared to measurements reported in previous works. A search for periodic modulation in available photometric data allowed us to confidently establish a period of 2.64119 ± 0.00420 d in archival ASAS3 data for CPD–27°1791. No period could be determined for the other five stars. Conclusions. The obtained results support the scenario that all He-rich stars are detectably magnetic and form an extension of the Ap star phenomenon to higher temperatures.

Schwingung eines Plasmazylinders in einem axialen Magnetfeld II

1960 ◽  
Vol 15 (3) ◽  
pp. 220-226 ◽  
Author(s):  
Klaus Körper
Keyword(s):  
Magnetic Field ◽  
Refractive Index ◽  
External Magnetic Field ◽  
Field Strength ◽  
Axial Magnetic Field ◽  
Surface Current ◽  
The Other ◽  
Plasma Cylinder ◽  
Resonance Frequencies ◽  
The Magnetic Field

Radial oscillations are excited in a homogeneous infinite plasma cylinder in a homogeneous axial magnetic field by a surface current which is homogeneous in the axial and azimuthal directions. The modes of oscillations corresponding to the axial and azimuthal components of current are not coupled, and so they may be analysed separately. The magnetic field in the plasma and vacuum is obtained, and the indices of refraction for both types of oscillations are discussed thoroughly. When the currents are parallel to the external magnetic field, the oscillations are characterized by the refractive index of Eccles. On the other hand, when the current is perpendicular to the magnetic field two resonance frequencies exist, which depend on the density of the plasma and the magnetic field strength. — In the latter case the radial characteristic oscillations of the plasma cylinder in an external magnetic field are considered.

scholarly journals PHOTON-PAIR CONVERSION INTO NEUTRINOS IN A STRONG MAGNETIC FIELD

2001 ◽  
Vol 16 (25) ◽  
pp. 1659-1665 ◽  
Author(s):  
A. V. KUZNETSOV ◽  
N. V. MIKHEEV
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Strong Magnetic Field ◽  
Asymptotic Form ◽  
Axial Vector ◽  
Electroweak Interaction ◽  
The Other ◽  
The Standard Model ◽  
Loop Amplitude ◽  
The Magnetic Field

A general analysis of the three-vertex loop amplitude in a strong magnetic field, based on the asymptotic form of the electron propagator in the field, is performed. In order to investigate the photon–neutrino process [Formula: see text], the vertex combinations of the scalar–vector–vector (SVV), pseudoscalar–vector–vector (PVV), three-vector (VVV), and axial-vector–vector–vector (AVV) types are considered. It is shown that only the SVV amplitude grows linearly with the magnetic field strength, while in the other amplitudes, PVV, VVV and AVV, the linearly growing terms are canceled. The process [Formula: see text] is investigated in the left–right-symmetric extension of the standard model of electroweak interaction, where the effective scalar νν e e coupling could exist. Possible astrophysical manifestations of the considered process are discussed.

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 Magnetic Fields in Dark Cloud Cores and H2O Masers

1990 ◽  
Vol 140 ◽  
pp. 305-308
Author(s):  
Rolf Güsten ◽  
Dirk Fiebig
Keyword(s):  
Magnetic Field ◽  
Star Formation ◽  
Field Strength ◽  
Kinetic Temperature ◽  
Dark Cloud ◽  
Dense Cores ◽  
Low Mass ◽  
Cloud Cores ◽  
First Time ◽  
The Magnetic Field

We present results of recent circular polarization experiments with the MPIfR 100-m telescope, revealing for the first time, the magnetic field strength towards interstellar H2O masers and the dense cores of local dark cloud complexes. Weak Zeeman splittings of a few 10 kHz only in the 22.235 GHz maser transition of the non-paramagnetic H2O molecule imply magnetic field strengths of ~ 50 mG in the dense (n ~ 1010 cm−3) masing layer. With the recently identified CCS radical it became possible to study the magnetic field associated with dense (~ 105 cm−3) dark cloud cores, the potential sites of future star formation. We report the detection of a −110μG field towards TMC-1C, a low-mass core associated with the Taurus Molecular Cloud. From complementary gas density and kinetic temperature probing measurements, we derive approximate equipartition between magnetic, gravitational and thermal energy for this clump.

scholarly journals Determining the Diameter of Reinforcing Bars Inside Concrete Structures Regardless of Magnetic Properties

2022 ◽  
Author(s):  
A.V. Mikhailov
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Numerical Experiments ◽  
High Accuracy ◽  
Reinforcing Bars ◽  
Reinforcing Bar ◽  
The Magnetic Field ◽  
Magnetizing Field

Abstract. In this work, using a series of numerical experiments, the dependence of the magnetic field strength of the response of the reinforcing bar to an external magnetizing field on the magnetic properties of the reinforcing bar was investigated. The possibility of determining with high accuracy the diameter of reinforcing bars, regardless of the magnetic properties of the material from which they are made, has been proven.

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.

Study of the Possibility of Estimating the Size of the Fractional-Dimensional Surface Layer by Electromagnetic Methods

2019 ◽  
Vol 945 ◽  
pp. 932-937 ◽  
Author(s):  
I.R. Kuzeev ◽  
V.Yu. Pivovarov
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Plate Thickness ◽  
Tangential Component ◽  
Surface Layers ◽  
Electromagnetic Methods ◽  
Internal Structures ◽  
First Time ◽  
The Magnetic Field

It is known that the surface of a solid body and its volume part are different forms of the same substance. There is a hypothesis about the presence of a transition fractional-dimensional layer, which is the "limiter" of the volume from the surface. It is assumed that this layer is able to store information about changes in the surface and internal structures of the solid. The origin of defects, leading to destruction, in most cases begins in the surface and surface layers of the metal. In this regard, the existence of fractional-dimensional layer as a subsurface structure, which has information about the properties of the whole solid, is of particular importance in the detection of possible critical defects. In order to test this hypothesis, an experiment was conducted based on measuring the magnetic field strength of a steel plate (25x25x2 mm) when its thickness was changed. With the help of sandpaper, one side of the plate was swamped, and the second remained unchanged. The measurements of the magnetic field strength components were carried out on both sides with the plate thickness decreasing by 0.08-0.1 mm from 2.0 to 0.3 mm. Applying a linear approximation to the obtained dependence of the average tangential component of the magnetic field on the plate thickness, it was found that the extrapolated approximation line comes to a point close to zero (0.01 mm). It was assumed that the value 0.01 determines the preliminary value of the fractional-dimensional layer. Such an experiment was carried out for the first time, so the results obtained so far will undoubtedly become the basis for further research in this area.

Asymmetric reconnection at the bow shock

2020 ◽  
Author(s):  
Herbert Gunell ◽  
Maria Hamrin ◽  
Oleksandr Goncharov ◽  
Alexandre De Spiegeleer ◽  
Stephen Fuselier ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Plasma Flow ◽  
Bow Shock ◽  
The Other ◽  
Magnetospheric Multiscale ◽  
The Magnetic Field

<p>Can reconnection be triggered as a directional discontinuity (DD) crosses the bow shock? Here we present some unique observations of asymmetric reconnection at a quasi-perpendicular bow shock as an interplanetary DD is crossing it simultaneously with the Magnetospheric Multiscale (MMS) mission. The data show indications of ongoing reconnection at the bow shock southward of the spacecraft. The DD is also observed by several upstream spacecraft (ACE, WIND, Geotail, and THEMIS B) and one downstream in the magnetosheath (Cluster 4), but none of them resolve signatures of ongoing reconnection. We therefore suggest that reconnection was temporarily triggered as the DD was compressed by the shock. Bow shock reconnection is inevitably asymmetric with both the density and the magnetic field strength being higher on one side of the X-line (the magneosheath side) than on the other side where the plasma flow also is supersonic (the solar wind side). Asymmetric reconnection of the bow shock type has never been studied before, and the data discussed here are hence unique.</p>

scholarly journals First EVN Maps of 6-GHz OH Lines in Star Forming Regions

1998 ◽  
Vol 164 ◽  
pp. 371-372
Author(s):  
J.-F. Desmurs ◽  
A. Baudry
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Circularly Polarized ◽  
Star Forming ◽  
Star Forming Regions ◽  
Adjacent Channels ◽  
First Time ◽  
The Magnetic Field

AbstractWe have used 3 antennas of the EVN to observe in 6 star-forming regions simultaneously, and for the first time, the 2 main lines of the J=5/2 state of OH with right and left circularly polarized feeds. Maser features and Zeeman pairs are identified by searching for emission over adjacent channels, and adjacent positions (within one synthesized beam) in both polarizations after we had mapped and used one selected simple channel as a reference. The magnetic field strength is thus estimated from the Zeeman pairs identified in our OH maps. We briefly present results obtained for W3(OH), ON1, and W51.

On the Configuration of the Magnetic Field of β CrB

1976 ◽  
Vol 32 ◽  
pp. 613-622
Author(s):  
I.A. Aslanov ◽  
Yu.S. Rustamov
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Radial Velocity ◽  
Magnetic Field Strength ◽  
Complex Shape ◽  
Rotation Period ◽  
Field Variation ◽  
Magnetic Field Variation ◽  
Secular Variations ◽  
The Magnetic Field

SummaryMeasurements of the radial velocities and magnetic field strength of β CrB were carried out. It is shown that there is a variability with the rotation period different for various elements. The curve of the magnetic field variation measured from lines of 5 different elements: FeI, CrI, CrII, TiII, ScII and CaI has a complex shape specific for each element. This may be due to the presence of magnetic spots on the stellar surface. A comparison with the radial velocity curves suggests the presence of a least 4 spots of Ti and Cr coinciding with magnetic spots. A change of the magnetic field with optical depth is shown. The curve of the Heffvariation with the rotation period is given. A possibility of secular variations of the magnetic field is shown.

Sign in / Sign up

Export Citation Format

Share Document