scholarly journals Observations of Orion Molecular Cloud with NMA

1994 ◽  
Vol 140 ◽  
pp. 185-189
Author(s):  
Y. Murata ◽  
R. Kawabe ◽  
M. Ishiguro ◽  
K.-I. Morita ◽  
T. Hasegawa ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Molecular Cloud ◽  
Gas Flow ◽  
Position Angle ◽  
Aperture Synthesis ◽  
Width Ratio ◽  
Length Width ◽  
The Magnetic Field

AbstractWe have made aperture synthesis multifield observations of Orion Molecular Cloud-1 (OMC-1) in the CS (J=1-0) line using the Nobeyama Millimeter Array (NMA), and obtained 9” resolution maps over 10’ length. The OMC-1 ridge shows a wiggled structure. The position angle of whole the ridge is ~ 0° - 10°, but ~ 20° - 30°around the clumps. It is possible to make this structure by the magnetic field with a position angle of ~ 150°. We also found filamentary structures in the northwest of Orion-KL, with a length-width ratio of more than 25, which are made by the gas flow from Orion-KL.

The Magnetic Field of the NGC 2024 Molecular Cloud

1999 ◽  
Vol 515 (1) ◽  
pp. 275-285 ◽  
Author(s):  
R. M. Crutcher ◽  
D. A. Roberts ◽  
T. H. Troland ◽  
W. M. Goss
Keyword(s):  
Magnetic Field ◽  
Molecular Cloud ◽  
The Magnetic Field

scholarly journals Magnetic Field Structure of Star Forming Regions: VLBI Spectral Line Results

1984 ◽  
Vol 110 ◽  
pp. 333-334
Author(s):  
J.A. Garcia-Barreto ◽  
B. F. Burke ◽  
M. J. Reid ◽  
J. M. Moran ◽  
A. D. Haschick
Keyword(s):  
Magnetic Field ◽  
Three Dimensional ◽  
Aperture Synthesis ◽  
Stokes Parameters ◽  
Hii Region ◽  
Star Forming ◽  
Star Forming Regions ◽  
Vlbi Observations ◽  
The Magnetic Field ◽  
Synthesis Experiment

Magnetic fields play a major role in the general dynamics of astronomical phenomena and particularly in the process of star formation. The magnetic field strength in galactic molecular clouds is of the order of few tens of μG. On a smaller scale, OH masers exhibit fields of the order of mG and these can probably be taken as representative of the magnetic field in the dense regions surrounding protostars. The OH molecule has been shown to emit highly circular and linearly polarized radiation. That it was indeed the action of the magnetic field that would give rise to the highly polarized spectrum of OH has been shown by the VLBI observations of Zeeman pairs of the 1720 and 6035 MHz by Lo et. al. and Moran et. al. VLBI observations of W3 (OH) revealed that the OH emission was coming from numerous discrete locations and that all spots fell within the continuum contours of the compact HII region. The most detailed VLBI aperture synthesis experiment of the 1665 MHz emission from W3 (OH) was carried out by Reid et. al. who found several Zeeman pairs and a characteristic maser clump size of 30 mas. In this work, we report the results of a 5 station VLBI aperture synthesis experiment of the 1665 MHz OH emission from W3 (OH) with full polarization information. We produced VLBI synthesis maps of all Stokes parameters of 16 spectral features that showed elliptical polarization. The magnitude and direction of the magnetic field have been obtained by the detection of 7 Zeeman pairs. The three dimensional orientation of the magnetic field can be obtained, following the theoretical arguments of Goldreich et. al., from the observation of π and σ components.

scholarly journals Study of the Magnetic Field of the Galaxy using Correlation Functions of the Intensity of Synchrotron Background Radio Emission

1996 ◽  
Vol 169 ◽  
pp. 615-616
Author(s):  
V.R. Shoutenkov
Keyword(s):  
Magnetic Field ◽  
Radio Emission ◽  
Correlation Functions ◽  
Theoretical Calculations ◽  
Angular Separation ◽  
Field Studies ◽  
Position Angle ◽  
The Galaxy ◽  
Image Position ◽  
The Magnetic Field

The possibility to study magnetic field of the Galaxy calculating correlation or structure functions of synchrotron background radio emission have been known long ago (Kaplan and Pikel'ner (1963); Getmantsev (1958)). But this method had not been as popular as other methods of magnetic field studies. However theoretical calculations made by Chibisov and Ptuskin (1981) showed that correlation functions of intensity of synchrotron background radio emission can give a lot of valuable information about galactic magnetic fields because of the intensity of synchrotron background radio emission depends on H⊥. According to this theory correlation C(θ, φ) and structure S(θ, φ) functions of intensity, as functions of angular separation θ between two lines of sight and position angle φ on the sky between this two lines of sight, can be presented as a sum of isotropic (not dependent from angle φ) and anisotropic parts:

scholarly journals Evolution of Multipolar Magnetic Fields in Isolated Neutron Stars and its effect on Pulsar Radio Emission

2000 ◽  
Vol 177 ◽  
pp. 265-266
Author(s):  
D. Mitra ◽  
S. Konar ◽  
D. Bhattacharya ◽  
A. V. Hoensbroech ◽  
J. H. Seiradakis ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Radio Emission ◽  
Neutron Stars ◽  
Pulse Shape ◽  
Position Angle ◽  
Emission Region ◽  
Pulsar Radio ◽  
Significant Frequency ◽  
The Magnetic Field ◽  
Pulsar Radio Emission

AbstractThe evolution of the multipolar structure of the magnetic field of isolated neutron stars is studied assuming the currents to be confined to the crust. Lower orders (≤ 25) of multipole are seen to evolve in a manner similar to the dipole suggesting little or no evolution of the expected pulse shape. We also study the multifrequency polarization position angle traverse of PSR B0329+54 and find a significant frequency dependence above 2.7 GHz. We interpret this as an evidence of strong multipolar magnetic field present in the radio emission region.

scholarly journals Relative Alignment between the Magnetic Field and Molecular Gas Structure in the Vela C Giant Molecular Cloud Using Low- and High-density Tracers

2019 ◽  
Vol 878 (2) ◽  
pp. 110 ◽  
Author(s):  
Laura M. Fissel ◽  
Peter A. R. Ade ◽  
Francesco E. Angilè ◽  
Peter Ashton ◽  
Steven J. Benton ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Molecular Cloud ◽  
High Density ◽  
Molecular Gas ◽  
Giant Molecular Cloud ◽  
The Magnetic Field

scholarly journals The Magnetic Field in the Perseus Molecular Cloud Complex

1990 ◽  
Vol 140 ◽  
pp. 319-320
Author(s):  
A.A. Goodman ◽  
P.C. Myers ◽  
P. Bastien ◽  
R.M. Crutcher ◽  
C. Heiles ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Molecular Cloud ◽  
Molecular Clouds ◽  
Dust Grains ◽  
Magnetically Aligned ◽  
Cloud Complex ◽  
The Magnetic Field ◽  
Co Emission ◽  
Selective Extinction

In Figure 1, we present a map of the polarization of background starlight in the Perseus region (Goodman, Bastien, Myers, and Menard 1989) superposed on contours of integrated 13CO emission (Bachiller and Cernicharo 1986). The polarization vectors map the plane-of-the-sky field (B⊥), assuming as usual that the observed polarization is the result of selective extinction by magnetically aligned dust grains associated with the molecular clouds between the observer and background stars (e.g. Dolginov 1989).

scholarly journals The influence of the magnetic field on the ionized gas flow adjacent to the porous wall

2010 ◽  
Vol 14 (suppl.) ◽  
pp. 183-196
Author(s):  
Slobodan Savic ◽  
Branko Obrovic ◽  
Milan Despotovic ◽  
Dusan Gordic
Keyword(s):  
Magnetic Field ◽  
Boundary Layer ◽  
Gas Flow ◽  
Great Influence ◽  
Porous Wall ◽  
Boundary Layer Separation ◽  
The Body ◽  
Ionized Gas ◽  
Friction Function ◽  
The Magnetic Field

This paper studies the influence of the magnetic field on the planar laminar steady flow of the ionized gas in the boundary layer. The present outer magnetic field is homogenous and perpendicular to the body within the fluid. The gas of the same physical characteristics as the gas in the main flow is injected (ejected) through the contour of the body. The governing boundary layer equations for different forms of the electroconductivity variation law are transformed, brought to a generalized form and solved numerically in a four-parametric approximation. It has been determined that the magnetic field, through the magnetic parameter, has a great influence on certain quantities and characteristics of the boundary layer. It has also been shown that this parameter has an especially significant influence on the non-dimensional friction function, and hence the boundary layer separation point.

scholarly journals Влияние нелинейности закона намагничивания феррожидкости на неустойчивость Кельвина--Гельмгольца

2021 ◽  
Vol 91 (8) ◽  
pp. 1199
Author(s):  
В.М. Коровин
Keyword(s):  
Magnetic Field ◽  
Field Intensity ◽  
Relative Velocity ◽  
Gas Flow ◽  
Magnetic Field Intensity ◽  
Homogeneous Magnetic Field ◽  
Helmholtz Instability ◽  
Magnetization Saturation ◽  
The Magnetic Field ◽  
Stability Area

We study Kelvin-Helmholtz instability which develops when a homogenous gas flow is moving over a horizontal surface of a ferrofluid of given physical properties moving in the same direction, in presence of a homogeneous magnetic field parallel to this direction. Magnetic field intensity range includes the values that correspond to the interval where magnetization curve reaches magnetization saturation level. Stability area is constructed in the “magnetic field intensity – dimensionless relative velocity of fluids” parameter plane.

scholarly journals The relative orientation between the magnetic field and gradients of surface brightness within thin velocity slices of 12CO and 13CO emission from the Taurus molecular cloud

2020 ◽  
Vol 496 (4) ◽  
pp. 4546-4564
Author(s):  
M Heyer ◽  
J D Soler ◽  
B Burkhart
Keyword(s):  
Magnetic Field ◽  
Mach Number ◽  
Turbulent Flows ◽  
Molecular Cloud ◽  
Random Errors ◽  
Spatial Gradients ◽  
Low Levels ◽  
The Magnetic Field ◽  
Taurus Molecular Cloud

ABSTRACT We examine the role of the interstellar magnetic field to modulate the orientation of turbulent flows within the Taurus molecular cloud using spatial gradients of thin velocity slices of 12CO and 13CO antenna temperatures. Our analysis accounts for the random errors of the gradients that arise from the thermal noise of the spectra. The orientations of the vectors normal to the antenna temperature gradient vectors are compared to the magnetic field orientations that are calculated from Planck 353 GHz polarization data. These relative orientations are parameterized with the projected Rayleigh statistic and mean resultant vector. For 12CO,   strongly parallel and strongly perpendicular relative orientations are found in 28 percent and 39 percent of the cloud area respectively. For the lower opacity 13CO emission, strongly parallel and strongly perpendicular orientations are found in 7 per cent and 43 per cent of the cloud area, respectively. For both isotopologues, strongly parallel or perpendicular alignments are restricted to localized regions with low levels of turbulence. If the relative orientations serve as an observational proxy to the Alfvénic Mach number then our results imply local variations of the Alfvénic Mach number throughout the cloud.

scholarly journals Comments

1990 ◽  
Vol 123 ◽  
pp. 417-419
Author(s):  
Fred Hoyle
Keyword(s):  
Magnetic Field ◽  
Solar System ◽  
Molecular Cloud ◽  
The Sun ◽  
Ultimate Explanation ◽  
Word Origin ◽  
Entire Universe ◽  
A Chain ◽  
The Magnetic Field

The word 'origin' is one of the most widely used in science. Yet it seems to me to be always used either improperly or ineffectively. Ineffective uses have a derivative quality about them. As an example, suppose we ask: What was the 'origin' of the magnetic field of the Sun? The best answer I suppose is that the magnetic field of the Sun was formed by the compression of a magnetic field that was present already in the gases of the molecular cloud in which the Sun and Solar System were formed some 4.5 X 109 years ago. But what then was the 'origin' of the field in the molecular cloud? It was present already in the gases from which our galaxy was formed, one might suggest. A further displacement then takes us to the manner of 'origin' of t he entire universe, so that no ultimate explanation has really been given. The problem has only been displaced along a chain until it passes into a mental fog through which some claim to see clearly but through which others, including myself, do not see at all.

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