Structure of the turbulent atomic gas and formation of molecular clouds

2008 ◽  
Vol 31 ◽  
pp. 15-18
Author(s):  
P. Hennebelle ◽  
E. Audit
Keyword(s):  
Molecular Clouds ◽  
Atomic Gas

scholarly journals Deterministic Self-Propagating Star Formation

1989 ◽  
Vol 120 ◽  
pp. 518-523
Author(s):  
Jan Palouš
Keyword(s):  
Star Formation ◽  
Simple Model ◽  
Molecular Cloud ◽  
Molecular Clouds ◽  
Large Scale ◽  
Galactic Evolution ◽  
Cloud Formation ◽  
Rotating Disks ◽  
Atomic Gas ◽  
High Column

AbstractThe evolution of large scale expanding structures in differentially rotating disks is studied. High column densities in some places may eventually lead to molecular cloud formation and initiate also star-formation. After some time, multi-structured arms evolve, where regions of intensive star-formation are separated from each other by regions of atomic gas or molecular clouds. This is due to the deterministic nature and to the coherence of this process. A simple model of galactic evolution is introduced and the different behaviour of Sa, Sb, and Sc galaxies is shown.

scholarly journals Towards a multitracer timeline of star formation in the LMC – I. Deriving the lifetimes of H i clouds

2020 ◽  
Vol 497 (2) ◽  
pp. 2286-2301 ◽  
Author(s):  
Jacob L Ward ◽  
Mélanie Chevance ◽  
J M Diederik Kruijssen ◽  
Alexander P S Hygate ◽  
Andreas Schruba ◽  
...  
Keyword(s):  
Star Formation ◽  
Time Scales ◽  
Time Scale ◽  
Molecular Clouds ◽  
Molecular Form ◽  
Cloud Formation ◽  
H Ii Regions ◽  
Star Forming ◽  
Atomic Gas ◽  
Gas Cloud

ABSTRACT The time-scales associated with the various stages of the star formation process remain poorly constrained. This includes the earliest phases of star formation, during which molecular clouds condense out of the atomic interstellar medium. We present the first in a series of papers with the ultimate goal of compiling the first multitracer timeline of star formation, through a comprehensive set of evolutionary phases from atomic gas clouds to unembedded young stellar populations. In this paper, we present an empirical determination of the lifetime of atomic clouds using the Uncertainty Principle for Star Formation formalism, based on the de-correlation of H α and H i emission as a function of spatial scale. We find an atomic gas cloud lifetime of 48$^{+13}_{-8}$ Myr. This time-scale is consistent with the predicted average atomic cloud lifetime in the LMC (based on galactic dynamics) that is dominated by the gravitational collapse of the mid-plane ISM. We also determine the overlap time-scale for which both H i and H α emissions are present to be very short (tover < 1.7 Myr), consistent with zero, indicating that there is a near-to-complete phase change of the gas to a molecular form in an intermediary stage between H i clouds and H ii regions. We utilize the time-scales derived in this work to place empirically determined limits on the time-scale of molecular cloud formation. By performing the same analysis with and without the 30 Doradus region included, we find that the most extreme star-forming environment in the LMC has little effect on the measured average atomic gas cloud lifetime. By measuring the lifetime of the atomic gas clouds, we place strong constraints on the physics that drives the formation of molecular clouds and establish a solid foundation for the development of a multitracer timeline of star formation in the LMC.

scholarly journals H I ZEEMAN EXPERIMENTS OF SHOCKED ATOMIC GAS IN TWO SUPERNOVA REMNANTS INTERACTING WITH MOLECULAR CLOUDS

2010 ◽  
Vol 140 (1) ◽  
pp. 262-265 ◽  
Author(s):  
Bon-Chul Koo ◽  
Carl Heiles ◽  
Snežana Stanimirović ◽  
Tom Troland
Keyword(s):  
Molecular Clouds ◽  
Supernova Remnants ◽  
Atomic Gas

THE TRANSITION FROM DIFFUSE ATOMIC GAS TO MOLECULAR CLOUD IN TAURUS

2019 ◽  
Author(s):  
Steven Federman ◽  
David Lambert ◽  
Gregory Mace ◽  
Nicolas Flagey ◽  
Paul Goldsmith ◽  
...  
Keyword(s):  
Molecular Cloud ◽  
Atomic Gas

Transport of Dust Grains in Turbulent Molecular Clouds

1998 ◽  
Vol 498 (2) ◽  
pp. 757-762 ◽  
Author(s):  
B. R. Ragot
Keyword(s):  
Molecular Clouds ◽  
Dust Grains

scholarly journals Molecules in the Magellanic Clouds

1991 ◽  
Vol 148 ◽  
pp. 415-420 ◽  
Author(s):  
R. S. Booth ◽  
Th. De Graauw
Keyword(s):  
High Resolution ◽  
Molecular Clouds ◽  
Short Review ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
Giant Molecular Clouds ◽  
Interstellar Molecules ◽  
First Time ◽  
Excitation Conditions

In this short review we describe recent new observations of millimetre transitions of molecules in selected regions of the Magellanic Clouds. The observations were made using the Swedish-ESO Submillimetre Telescope, SEST, (Booth et al. 1989), the relatively high resolution of which facilitates, for the first time, observations of individual giant molecular clouds in the Magellanic Clouds. We have mapped the distribution of the emission from the two lowest rotational transitions of 12CO and 13CO and hence have derived excitation conditions for the molecule. In addition, we have observed several well-known interstellar molecules in the same regions, thus doubling the number of known molecules in the Large Magellanic Cloud (LMC). The fact that all the observations have been made under controlled conditions with the same telescope enables a reasonable intercomparison of the molecular column densities. In particular, we are able to observe the relative abundances among the different isotopically substituted species of CO.

Compact cores of molecular clouds in NGC 1333/IRAS 6–9

2000 ◽  
Vol 24 (4) ◽  
pp. 511-521
Author(s):  
Jin Sun ◽  
Jia-jian Shen ◽  
Yan-ping Zhang ◽  
Jin-jiang Sun
Keyword(s):  
Molecular Clouds
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