Molecular Clouds in Cygnus. II. Statistical Studies of Star-forming Regions

1996 ◽  
Vol 466 ◽  
pp. 282 ◽  
Author(s):  
Kazuhito Dobashi ◽  
Jean-Philippe Bernard ◽  
Yasuo Fukui
Keyword(s):  
Molecular Clouds ◽  
Star Forming ◽  
Star Forming Regions ◽  
Statistical Studies

AMBIPOLAR DIFFUSION AND TURBULENT MAGNETIC FIELDS IN MOLECULAR CLOUDS

2011 ◽  
Vol 26 (04) ◽  
pp. 235-249 ◽  
Author(s):  
MARTIN HOUDE ◽  
TALAYEH HEZAREH ◽  
HUA-BAI LI ◽  
THOMAS G. PHILLIPS
Keyword(s):  
Magnetic Fields ◽  
Molecular Clouds ◽  
Ambipolar Diffusion ◽  
Star Forming ◽  
Star Forming Regions ◽  
Spin Interactions ◽  
Line Narrowing ◽  
Weakly Ionized ◽  
Novel Method

We review the introduction and development of a novel method for the characterization of magnetic fields in star-forming regions. The technique is based on the comparison of spectral line profiles from coexistent neutral and ion molecular species commonly detected in molecular clouds, sites of star formation. Unlike other methods used to study magnetic fields in the cold interstellar medium, this ion/neutral technique is not based on spin interactions with the field. Instead, it relies on and takes advantage of the strong cyclotron coupling between the ions and magnetic fields, thus exposing what is probably the clearest observational manifestation of magnetic fields in the cold, weakly ionized gas that characterizes the interior of molecular clouds. We will show how recent development and modeling of the ensuing ion line narrowing effect leads to a determination of the ambipolar diffusion scale involving the turbulent component of magnetic fields in star-forming regions, as well as the strength of the ordered component of the magnetic field.

scholarly journals The atomic hydrogen/molecular cloud association: an unavoidable relationship

1991 ◽  
Vol 147 ◽  
pp. 37-40
Author(s):  
G. Joncas
Keyword(s):  
Atomic Hydrogen ◽  
Molecular Clouds ◽  
Large Scale ◽  
Young Stars ◽  
Physical Processes ◽  
Star Forming ◽  
Dark Clouds ◽  
Star Forming Regions ◽  
The Impact

The presence of HI in the interstellar medium is ubiquitous. HI is the principal actor in the majority of the physical processes at work in our Galaxy. Restricting ourselves to the topics of this symposium, atomic hydrogen is involved with the formation of molecular clouds and is one of the byproducts of their destruction by young stars. HI has different roles during a molecular cloud's life. I will discuss here a case of coexisting HI and H2 at large scale and the origin of HI in star forming regions. For completeness' sake, it should be mentionned that there are at least three other aspects of HI involvement: HI envelopes around molecular clouds, the impact of SNRs (see work on IC 443), and the role of HI in quiescent dark clouds (see van der Werf's work).

Simulating star-forming regions in spiral galaxies with AMUSE

2019 ◽  
Vol 14 (S351) ◽  
pp. 216-219
Author(s):  
Steven Rieder ◽  
Clare Dobbs ◽  
Thomas Bending
Keyword(s):  
Gas Dynamics ◽  
Molecular Clouds ◽  
Spiral Galaxies ◽  
Initial Conditions ◽  
Cluster Formation ◽  
Star Cluster ◽  
Star Forming ◽  
Star Forming Regions ◽  
Formation And Evolution ◽  
Spiral Arm

AbstractWe present a model for hydrodynamic + N-body simulations of star cluster formation and evolution using AMUSE. Our model includes gas dynamics, star formation in regions of dense gas, stellar evolution and a galactic tidal spiral potential, thus incorporating most of the processes that play a role in the evolution of star clusters.We test our model on initial conditions of two colliding molecular clouds as well as a section of a spiral arm from a previous galaxy simulation.

scholarly journals The atomic hydrogen/molecular cloud association: an unavoidable relationship

1991 ◽  
Vol 147 ◽  
pp. 37-40
Author(s):  
G. Joncas
Keyword(s):  
Atomic Hydrogen ◽  
Molecular Clouds ◽  
Large Scale ◽  
Young Stars ◽  
Physical Processes ◽  
Star Forming ◽  
Dark Clouds ◽  
Star Forming Regions ◽  
The Impact

The presence of HI in the interstellar medium is ubiquitous. HI is the principal actor in the majority of the physical processes at work in our Galaxy. Restricting ourselves to the topics of this symposium, atomic hydrogen is involved with the formation of molecular clouds and is one of the byproducts of their destruction by young stars. HI has different roles during a molecular cloud's life. I will discuss here a case of coexisting HI and H2 at large scale and the origin of HI in star forming regions. For completeness' sake, it should be mentionned that there are at least three other aspects of HI involvement: HI envelopes around molecular clouds, the impact of SNRs (see work on IC 443), and the role of HI in quiescent dark clouds (see van der Werf's work).

scholarly journals A Denis Survey of Star Forming Regions

1998 ◽  
Vol 179 ◽  
pp. 172-174 ◽  
Author(s):  
E. Copet
Keyword(s):  
Molecular Clouds ◽  
Stellar Population ◽  
Giant Molecular Clouds ◽  
The South ◽  
Large Format ◽  
Star Forming ◽  
Star Forming Regions ◽  
Array Detectors

A complete census of embedded stellar population can be made by exploring in the infrared large areas of the sky in which giant molecular clouds extend. Very recently, thanks to the of large format IR array detectors, studies of young stellar population in GMCs, have been undertaken by different authors (i.e., Lada et al. 1991) but all these observations were limited to relatively small regions of the whole GMCs, the DENIS project (Epchtein, this volume, p. 106) surveys the south hemisphere at I, J and Ks bands, including most of these clouds.

scholarly journals A Guide to Comparisons of Star Formation Simulations with Observations

2010 ◽  
Vol 6 (S270) ◽  
pp. 511-519 ◽  
Author(s):  
Alyssa A. Goodman
Keyword(s):  
Star Formation ◽  
Spectral Line ◽  
Molecular Clouds ◽  
Direct Relationship ◽  
Statistical Tests ◽  
Random Processes ◽  
Mass Function ◽  
Star Forming ◽  
Star Forming Regions ◽  
Taste Testing

AbstractWe review an approach to observation-theory comparisons we call “Taste-Testing.” In this approach, synthetic observations are made of numerical simulations, and then both real and synthetic observations are “tasted” (compared) using a variety of statistical tests. We first lay out arguments for bringing theory to observational space rather than observations to theory space. Next, we explain that generating synthetic observations is only a step along the way to the quantitative, statistical, taste tests that offer the most insight. We offer a set of examples focused on polarimetry, scattering and emission by dust, and spectral-line mapping in star-forming regions. We conclude with a discussion of the connection between statistical tests used to date and the physics we seek to understand. In particular, we suggest that the “lognormal” nature of molecular clouds can be created by the interaction of many random processes, as can the lognormal nature of the IMF, so that the fact that both the “Clump Mass Function” (CMF) and IMF appear lognormal does not necessarily imply a direct relationship between them.

scholarly journals A sample of star forming regions triggered by cloud-cloud collision

2006 ◽  
Vol 2 (S237) ◽  
pp. 498-498
Author(s):  
Bei Xin ◽  
Jun-Jie Wang
Keyword(s):  
Molecular Clouds ◽  
Efficient Mechanism ◽  
Star Forming ◽  
Star Forming Regions ◽  
The Universe

Collision between molecular clouds is considered an efficient mechanism to trigger cloud collapse to form stars. Various observations show that the process is taking place in the universe (Vallee 1995; Wang et al. 2004).

scholarly journals SK 1: A possible case of triggered star formation in perseus

2006 ◽  
Vol 2 (S237) ◽  
pp. 217-221
Author(s):  
Miriam Rengel ◽  
Klaus Hodapp ◽  
Jochen Eislöffel
Keyword(s):  
Star Formation ◽  
Molecular Clouds ◽  
Thermal Emission ◽  
Young Stellar Objects ◽  
Wide Field ◽  
Dust Shell ◽  
Stellar Objects ◽  
Star Forming ◽  
Star Forming Regions ◽  
Suitable Target

AbstractAccording to a triggered star formation scenario (e.g. Martin-Pintado & Cernicharo 1987) outflows powered by young stellar objects shape the molecular clouds, can dig cavities, and trigger new star formation. NGC 1333 is an active site of low- and intermediate star formation in Perseus and is a suggested site of self-regulated star formation (Norman & Silk 1980). Therefore it is a suitable target for a study of triggered star formation (e.g. Sandell & Knee 2001, SK1). On the other hand, continuum sub-mm observations of star forming regions can detect dust thermal emission of embedded sources (which drive outflows), and further detailed structures.Within the framework of our wide-field mapping of star formation regions in the Perseus and Orion molecular clouds using SCUBA at 850 and 450 μm, we mapped NCG 1333 with an area of around 14′× 21′. The maps show more structure than the previous maps of the region observed in sub-mm. We have unveiled the known embedded SK 1 source (in the dust shell of the SSV 13 ridge) and detailed structure of the region, among some other young protostars.In agreement with the SK 1 observations, our map of the region shows lumpy filaments and shells/cavities that seem to be created by outflows. The measured mass of SK 1 (~0.07 M) is much less than its virial mass (~0.2-1 M). Our observations support the idea of SK 1 as an event triggered by outflow-driven shells in NGC 1333 (induced by an increase in gas pressure and density due to radiation pressure from the stellar winds that have presumably created the dust shell). This kind of evidences provides a more thorough understanding of the star formation regulation processes.

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