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 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.

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 EVN observations of 6.7 GHz methanol maser polarization in massive star-forming regions

2019 ◽  
Vol 623 ◽  
pp. A130 ◽  
Author(s):  
G. Surcis ◽  
W. H. T. Vlemmings ◽  
H. J. van Langevelde ◽  
B. Hutawarakorn Kramer ◽  
A. Bartkiewicz
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Massive Star ◽  
Zeeman Splitting ◽  
Limited Sample ◽  
Star Forming ◽  
Molecular Outflows ◽  
Star Forming Regions ◽  
The Magnetic Field

Context. Magnetohydrodynamical simulations show that the magnetic field can drive molecular outflows during the formation of massive protostars. The best probe to observationally measure both the morphology and the strength of this magnetic field at scales of 10–100 au is maser polarization. Aims. We measure the direction of magnetic fields at milliarcsecond resolution around a sample of massive star-forming regions to determine whether there is a relation between the orientation of the magnetic field and of the outflows. In addition, by estimating the magnetic field strength via the Zeeman splitting measurements, the role of magnetic field in the dynamics of the massive star-forming region is investigated. Methods. We selected a flux-limited sample of 31 massive star-forming regions to perform a statistical analysis of the magnetic field properties with respect to the molecular outflows characteristics. We report the linearly and circularly polarized emission of 6.7 GHz CH3OH masers towards seven massive star-forming regions of the total sample with the European VLBI Network. The sources are: G23.44−0.18, G25.83−0.18, G25.71−0.04, G28.31−0.39, G28.83−0.25, G29.96−0.02, and G43.80−0.13. Results. We identified a total of 219 CH3OH maser features, 47 and 2 of which showed linearly and circularly polarized emission, respectively. We measured well-ordered linear polarization vectors around all the massive young stellar objects and Zeeman splitting towards G25.71−0.04 and G28.83−0.25. Thanks to recent theoretical results, we were able to provide lower limits to the magnetic field strength from our Zeeman splitting measurements. Conclusions. We further confirm (based on ∼80% of the total flux-limited sample) that the magnetic field on scales of 10–100 au is preferentially oriented along the outflow axes. The estimated magnetic field strength of |B||| > 61 mG and >21 mG towards G25.71−0.04 and G28.83−0.25, respectively, indicates that it dominates the dynamics of the gas in both regions.

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.

scholarly journals The effects of magnetic field strength on the properties of wind generated from hot accretion flow

2018 ◽  
Vol 615 ◽  
pp. A35 ◽  
Author(s):  
De-Fu Bu ◽  
Amin Mosallanezhad
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Pressure Gradient ◽  
Magnetic Field Strength ◽  
Magnetic Pressure ◽  
Gas Pressure ◽  
Accretion Flow ◽  
Accretion Flows ◽  
Black Hole Accretion ◽  
The Magnetic Field

Context. Observations indicate that wind can be generated in hot accretion flow. Wind generated from weakly magnetized accretion flow has been studied. However, the properties of wind generated from strongly magnetized hot accretion flow have not been studied. Aims. In this paper, we study the properties of wind generated from both weakly and strongly magnetized accretion flow. We focus on how the magnetic field strength affects the wind properties. Methods. We solve steady-state two-dimensional magnetohydrodynamic equations of black hole accretion in the presence of a largescale magnetic field. We assume self-similarity in radial direction. The magnetic field is assumed to be evenly symmetric with the equatorial plane. Results. We find that wind exists in both weakly and strongly magnetized accretion flows. When the magnetic field is weak (magnetic pressure is more than two orders of magnitude smaller than gas pressure), wind is driven by gas pressure gradient and centrifugal forces. When the magnetic field is strong (magnetic pressure is slightly smaller than gas pressure), wind is driven by gas pressure gradient and magnetic pressure gradient forces. The power of wind in the strongly magnetized case is just slightly larger than that in the weakly magnetized case. The power of wind lies in a range PW ~ 10−4–10−3 Ṁinc2, with Ṁin and c being mass inflow rate and speed of light, respectively. The possible role of wind in active galactic nuclei feedback is briefly discussed.

COMPARISON OF CARDIAC MAGNETIC FIELD DISTRIBUTIONS DURING DEPOLARIZATION AND REPOLARIZATION

2003 ◽  
Vol 13 (12) ◽  
pp. 3783-3789 ◽  
Author(s):  
F. E. SMITH ◽  
P. LANGLEY ◽  
L. TRAHMS ◽  
U. STEINHOFF ◽  
J. P. BOURKE ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Field Distribution ◽  
Normal Subjects ◽  
The Body ◽  
Magnetic Field Distribution ◽  
T Wave ◽  
High Magnetic Field Strength ◽  
The Magnetic Field

Multichannel magnetocardiography measures the magnetic field distribution of the human heart noninvasively from many sites over the body surface. Multichannel magnetocardiogram (MCG) analysis enables regional temporal differences in the distribution of cardiac magnetic field strength during depolarization and repolarization to be identified, allowing estimation of the global and local inhomogeneity of the cardiac activation process. The aim of this study was to compare the spatial distribution of cardiac magnetic field strength during ventricular depolarization and repolarization in both normal subjects and patients with cardiac abnormalities, obtaining amplitude measurements by magnetocardiography. MCGs were recorded at 49 sites over the heart from three normal subjects and two patients with inverted T-wave conditions. The magnetic field intensity during depolarization and repolarization was measured automatically for each channel and displayed spatially as contour maps. A Pearson correlation was used to determine the spatial relationship between the variables. For normal subjects, magnetic field strength maps during depolarization (R-wave) showed two asymmetric regions of magnetic field strength with a high positive value in the lower half of the chest and a high negative value above this. The regions of high R-wave amplitude corresponded spatially to concentrated asymmetric regions of high magnetic field strength during repolarization (T-wave). Pearson-r correlation coefficients of 0.7 (p<0.01), 0.8 (p<0.01) and 0.9 (p<0.01) were obtained from this analysis for the three normal subjects. A negative correlation coefficient of -0.7 (p<0.01) was obtained for one of the subjects with inverted T-wave abnormalities, suggesting similar but inverted magnetic field and current distributions to normal subjects. Even with the high correlation values in these four subjects, the MCG was able to identify differences in the distribution of magnetic field strength, with a shift in the T-wave relative to the R-wave. The measurement of cardiac magnetic field distribution during depolarization and repolarization of normal subjects and patients with clinical abnormalities should enable the improvement of theoretical models for the explanation of the cardiac depolarization and repolarization processes.

scholarly journals Transport of hyperpolarized samples in dissolution-DNP experiments

2019 ◽  
Vol 21 (25) ◽  
pp. 13696-13705 ◽  
Author(s):  
Alexey S. Kiryutin ◽  
Bogdan A. Rodin ◽  
Alexandra V. Yurkovskaya ◽  
Konstantin L. Ivanov ◽  
Dennis Kurzbach ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Dynamic Nuclear Polarization ◽  
Nuclear Polarization ◽  
Sample Transfer ◽  
The Magnetic Field ◽  
Dissolution Dynamic Nuclear Polarization

The magnetic field strength during sample transfer in dissolution dynamic nuclear polarization influences the resulting spectra.

Zero-Field Level Crossing in the Helium Atom

1972 ◽  
Vol 50 (2) ◽  
pp. 116-118 ◽  
Author(s):  
C. W. T. Chien ◽  
R. E. Bardsley ◽  
F. W. Dalby
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Helium Atom ◽  
Cross Sections ◽  
Zero Field ◽  
Level Crossing ◽  
Field Level ◽  
Collision Cross Sections ◽  
The Magnetic Field

Zero-field level-crossing techniques have been used to measure some upper-state lifetimes of the helium atom. The half-widths of curves obtained by plotting the polarization against the magnetic field strength for the n1D–21D transitions yielded lifetimes of 2.03 × 10−8 s for the 31D state, 3.36 × 10−8 s for the 41D state, and 7.44 × 10−8 s for the 51D state. Collision cross sections for these 1D levels were also determined.

scholarly journals The magnetic field in the dense photodissociation region of DR 21

2020 ◽  
Author(s):  
Atanu Koley ◽  
Nirupam Roy ◽  
Karl M Menten ◽  
Arshia M Jacob ◽  
Thushara G S Pillai ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Zeeman Effect ◽  
Zeeman Splitting ◽  
Weak Field ◽  
Field Energy ◽  
Evolutionary Stage ◽  
Maser Emission ◽  
The Magnetic Field ◽  
Photodissociation Region

Abstract Measuring interstellar magnetic fields is extremely important for understanding their role in different evolutionary stages of interstellar clouds and of star formation. However, detecting the weak field is observationally challenging. We present measurements of the Zeeman effect in the 1665 and 1667 MHz (18 cm) lines of the hydroxyl radical (OH) lines toward the dense photodissociation region (PDR) associated with the compact H ii region DR 21 (Main). From the OH 18 cm absorption, observed with the Karl G. Jansky Very Large Array, we find that the line of sight magnetic field in this region is ∼0.13 mG. The same transitions in maser emission toward the neighbouring DR 21(OH) and W 75S-FR1 regions also exhibit the Zeeman splitting. Along with the OH data, we use [C ii] 158 μm line and hydrogen radio recombination line data to constrain the physical conditions and the kinematics of the region. We find the OH column density to be ∼3.6 × 1016(Tex/25 K) cm−2, and that the 1665 and 1667 MHz absorption lines are originating from the gas where OH and C+ are co-existing in the PDR. Under reasonable assumptions, we find the measured magnetic field strength for the PDR to be lower than the value expected from the commonly discussed density–magnetic field relation while the field strength values estimated from the maser emission are roughly consistent with the same. Finally, we compare the magnetic field energy density with the overall energetics of DR 21’s PDR and find that, in its current evolutionary stage, the magnetic field is not dynamically important.

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