EVOLUTION OF INTERSTELLAR MOLECULAR CLOUDS: AN INTEGRATED HYDRODYNAMIC STUDY OF A COLLAPSING CLOUD

1980 ◽  
pp. 289-301
Author(s):  
H. Gerola ◽  
A.E. Glassgold
Keyword(s):  
Molecular Clouds ◽  
Hydrodynamic Study ◽  
Collapsing Cloud ◽  
Interstellar Molecular Clouds

scholarly journals Measurement of Magnetic-Field Strengths in Molecular Clouds: Detection of OH Line Zeeman Splitting

1987 ◽  
Vol 115 ◽  
pp. 55-57
Author(s):  
I. Kazès ◽  
R. M. Crutcher ◽  
T. H. Troland
Keyword(s):  
Magnetic Field ◽  
Radio Telescope ◽  
Molecular Clouds ◽  
Stokes Parameter ◽  
Zeeman Splitting ◽  
Spectral Lines ◽  
First Results ◽  
Extended Program ◽  
Interstellar Molecular Clouds ◽  
Field Strengths

We report here the first results of an extended program to measure magnetic-field strengths in interstellar molecular clouds. The very large radio telescope located near Nancay, France, has been used to measure the Stokes-parameter I and V spectra of the 1665 and 1667 MHz lines of OH in emission and in absorption from extended (non-masing) molecular clouds. Signals in the V spectra are produced by Zeeman splitting of the spectral lines; we derive magnetic-field strengths or limits from these data.

scholarly journals An experimental study of the surface formation of methane in interstellar molecular clouds

2020 ◽  
Vol 4 (8) ◽  
pp. 781-785 ◽  
Author(s):  
D. Qasim ◽  
G. Fedoseev ◽  
K.-J. Chuang ◽  
J. He ◽  
S. Ioppolo ◽  
...  
Keyword(s):  
Experimental Study ◽  
Molecular Clouds ◽  
Surface Formation ◽  
Interstellar Molecular Clouds

scholarly journals Kinematics and Dynamics of Dense Clouds

1977 ◽  
Vol 75 ◽  
pp. 69-94
Author(s):  
James Lequeux
Keyword(s):  
Magnetic Field ◽  
Star Formation ◽  
Molecular Clouds ◽  
Kinematics And Dynamics ◽  
Interstellar Molecular Clouds ◽  
Maser Sources

Star formation is widely considered as resulting from the collapse of interstellar molecular clouds. The purpose of this paper is to review the observational evidences for collapse in dense clouds, and also for the factors which can play against collapse (turbulence, rotation, magnetic field). We shall also examine to which extent the maser sources (OH, H2O, SiO) can be related to star formation. An overlap with the review papers given by P. Thaddeus, P.G. Mezger, and to some extent by C.G. Wynn-Williams and L. Mestel appears unavoidable.

scholarly journals Hierarchical structure of the interstellar molecular clouds and star formation

2017 ◽  
Vol 26 (1) ◽  
Author(s):  
Alexander E. Dudorov ◽  
Sergey A. Khaibrakhmanov
Keyword(s):  
Magnetic Field ◽  
Molecular Clouds ◽  
Hierarchical Structures ◽  
Mhd Turbulence ◽  
Parallel Magnetic Field ◽  
Density Profiles ◽  
Statistical Correlations ◽  
Cloud Cores ◽  
Interstellar Molecular Clouds ◽  
The Magnetic Field

AbstractProperties of the hierarchical structures of interstellar molecular clouds are discussed. Particular attention is paid to the statistical correlations between velocity dispersion and size, and between the magnetic field strength and gas density. We investigate the formation of some hierarchical structures with the help of numerical MHD simulations using the ENLIL code. The simulations show that the interstellar molecular filaments with parallel magnetic field and molecular cores can form via the collapse and fragmentation of cylindrical molecular clouds. The parallelmagnetic field halts the radial collapse of the cylindrical cloud maintaining its nearly constant radius ~0.1 pc. The observed filaments with perpendicularmagnetic field can form as a result of themagnetostatic contraction of oblate molecular clouds under the action of Alfvén and MHD turbulence. The theoretical density profiles are fitted with the Plummer-like function and agree with observed profiles of the filaments in Gould’s Belt. The characteristics of molecular cloud cores found in our simulations are in agreement with observations.

High-resolution interstellar spectroscopy and star formation

1981 ◽  
Vol 303 (1480) ◽  
pp. 565-579 ◽  
Keyword(s):  
Star Formation ◽  
Molecular Clouds ◽  
Molecular Spectroscopy ◽  
Active Regions ◽  
Infrared Source ◽  
Very Large Array ◽  
Dark Clouds ◽  
The Past ◽  
Different Types ◽  
Interstellar Molecular Clouds

During the past several years, high spatial and spectral resolution molecular spectroscopy has greatly contributed to our knowledge of the physics, dynamics and chemistry of interstellar molecular clouds and thus has led to a better understanding of the conditions that lead to star formation. According to their physical properties, molecular clouds can be grouped into four different types: (i) the dark clouds, (ii) the molecular clouds associated with H+ regions, (iii) the ‘protostellar’ (or maser) environment, and (iv) the molecular envelopes of late-type stars. The first three types of cloud contain generally active regions of star formation. As typical examples the properties are discussed of individual clouds such as TMC 1 and L 183 for the cold clouds, S 140 and S 106 for the warm dark clouds with embedded infrared source, and Orion A for a region with associated H+ region. In S 140, NH 3 is clumped on a scale of not more than 20", whereas recent observations towards Orion A with the Very Large Array show that NH 3 clumps on a scale smaller than 5".

Millimetre-wave laboratory detection of H2COH+

1994 ◽  
Vol 72 (11-12) ◽  
pp. 1078-1081 ◽  
Author(s):  
D. Chomiak ◽  
A. Taleb-Bendiab ◽  
S. Civis ◽  
T. Amano
Keyword(s):  
Ground State ◽  
Molecular Clouds ◽  
Rotational Transition ◽  
Infrared Detection ◽  
Rotational Spectrum ◽  
Molecular Constants ◽  
Negative Glow ◽  
Millimetre Wave ◽  
Magnetically Confined ◽  
Interstellar Molecular Clouds

The ground-state rotational spectrum of protonated formaldehyde, H2COH+, has been identified and assigned following the infrared detection by Amano and Warner using a magnetically confined extended negative glow discharge as a production source. The molecular constants have been determined more accurately. These parameters provide the pure rotational transition frequencies that are accurate enough for radio astronomical searches for this ion in interstellar molecular clouds.

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