The role of magnetic field in the formation and evolution of filamentary molecular clouds

2018 ◽  
Vol 14 (A30) ◽  
pp. 100-100
Author(s):  
Shu-ichiro Inutsuka
Keyword(s):  
Magnetic Field ◽  
Star Formation ◽  
Molecular Cloud ◽  
Molecular Clouds ◽  
Mass Function ◽  
Convincing Evidence ◽  
Formation And Evolution ◽  
Cloud Cores ◽  
Compressed Layer

AbstractRecent observations have emphasized the importance of the formation and evolution of magnetized filamentary molecular clouds in the process of star formation. Theoretical and observational investigations have provided convincing evidence for the formation of molecular cloud cores by the gravitational fragmentation of filamentary molecular clouds. In this review we summarize our current understanding of various processes that are required in describing the filamentary molecular clouds. Especially we can explain a robust formation mechanism of filamentary molecular clouds in a shock compressed layer, which is in analogy to the making of “Sushi.” We also discuss the origin of the mass function of cores.

scholarly journals Formation of young massive clusters from turbulent molecular clouds

2015 ◽  
Vol 12 (S316) ◽  
pp. 25-30
Author(s):  
Michiko S. Fujii ◽  
Simon Portegies Zwart
Keyword(s):  
Power Law ◽  
Molecular Cloud ◽  
Molecular Clouds ◽  
Mass Function ◽  
Young Star ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Formation And Evolution ◽  
Young Star Clusters ◽  
Massive Clusters

AbstractWe simulate the formation and evolution of young star clusters from turbulent molecular clouds using smoothed-particle hydrodynamics and direct N-body methods. We find that the shape of the cluster mass function that originates from an individual molecular cloud is consistent with a Schechter function with power-law slopes of β = −1.73. The superposition of mass functions turn out to have a power-law slope of < −2. The mass of the most massive cluster formed from a single molecular cloud with mass Mg scales with 6.1 M0.51g. The molecular clouds that tend to form massive clusters are much denser than those typical found in the Milky Way. The velocity dispersion of such molecular clouds reaches 20km s−1 and it is consistent with the relative velocity of the molecular clouds observed near NGC 3603 and Westerlund 2, for which a triggered star formation by cloud-cloud collisions is suggested.

scholarly journals Filament Fragmentation

2001 ◽  
Vol 200 ◽  
pp. 391-400 ◽  
Author(s):  
Shu-ichiro Inutsuka ◽  
Toru Tsuribe
Keyword(s):  
Molecular Clouds ◽  
Mass Function ◽  
Mass Scale ◽  
Thermal Processes ◽  
Dense Cores ◽  
Dense Molecular Cloud ◽  
Basic Physics ◽  
Formation And Evolution ◽  
Field Lines ◽  
Cloud Cores

The formation and evolution processes of magnetized filamentary molecular clouds are investigated in detail by linear stability analyses and non-linear numerical calculations. A one-dimensionally compressed self-gravitating sheet-like cloud breaks up into filamentary clouds. The directions of the longitudinal axes of the resulting filaments are perpendicular to the directions of magnetic field lines unless the column density of the sheet is very small. These magnetized filaments tend to collapse radially without characteristic density, length, and mass scale for the further fragmentation during the isothermal phase. The characteristic minimum mass for the final fragmentation is obtained by the investigation of thermal processes. The essential points of the above processes are analytically explained in terms of the basic physics. A theory for the expected mass function of dense molecular cloud cores is obtained. The expected mean surface density of companions of dense cores is also discussed.

Observations of magnetic fields in star-forming clouds

2018 ◽  
Vol 14 (A30) ◽  
pp. 101-101
Author(s):  
Juan D. Soler
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Molecular Clouds ◽  
Spatial Scales ◽  
Cloud Formation ◽  
Star Forming ◽  
Formation And Evolution ◽  
Under Construction ◽  
The Magnetic Field

AbstractThis review examines observations of magnetic fields in molecular clouds, that is, at spatial scales ranging from tens to tenths of parsecs and densities up to hundreds of particles per cubic centimetre. I will briefly summarize the techniques for observing and mapping magnetic fields in molecular clouds. I will review important examples of observational results obtained using each technique and their implications for our understanding of the role of the magnetic field in molecular cloud formation and evolution. Finally, I will briefly discuss the prospects for advances in our observational capabilities with telescopes and instruments now beginning operation or under construction.

scholarly journals Three-dimensional MHD simulations of molecular cloud fragmentation regulated by gravity, ambipolar diffusion, and turbulence

2008 ◽  
Vol 4 (S259) ◽  
pp. 115-116
Author(s):  
Takahiro Kudoh ◽  
Shantanu Basu
Keyword(s):  
Star Formation ◽  
Magnetic Fields ◽  
Time Scale ◽  
Molecular Cloud ◽  
Molecular Clouds ◽  
Three Dimensional ◽  
Core Formation ◽  
Mhd Simulations ◽  
Dimensional Simulation

AbstractWe find that the star formation is accelerated by the supersonic turbulence in the magnetically dominated (subcritical) clouds. We employ a fully three-dimensional simulation to study the role of magnetic fields and ion-neutral friction in regulating gravitationally driven fragmentation of molecular clouds. The time-scale of collapsing core formation in subcritical clouds is a few ×107 years when starting with small subsonic perturbations. However, it is shortened to approximately several ×106 years by the supersonic flows in the clouds. We confirm that higher-spacial resolution simulations also show the same result.

scholarly journals Magnetic fields and star formation – new observational results

2006 ◽  
Vol 2 (S237) ◽  
pp. 141-147
Author(s):  
Richard M. Crutcher ◽  
Thomas H. Troland
Keyword(s):  
Magnetic Field ◽  
Star Formation ◽  
Magnetic Fields ◽  
Interstellar Medium ◽  
Observational Data ◽  
Molecular Clouds ◽  
Dark Cloud ◽  
Magnetic Field Model ◽  
Field Lines ◽  
Cloud Cores

AbstractAlthough the subject of this meeting is triggered star formation in a turbulent interstellar medium, it remains unsettled what role magnetic fields play in the star formation process. This paper briefly reviews star formation model predictions for the ratio of mass to magnetic flux, describes how Zeeman observations can test these predictions, describes new results – an extensive OH Zeeman survey of dark cloud cores with the Arecibo telescope, and discusses the implications. Conclusions are that the new data support and extend the conclusions based on the older observational results – that observational data on magnetic fields in molecular clouds are consistent with the strong magnetic field model of star formation. In addition, the observational data on magnetic field strengths in the interstellar medium strongly suggest that molecular clouds must form primarily by accumulation of matter along field lines. Finally, a future observational project is described that could definitively test the ambipolar diffusion model for the formation of cores and hence of stars.

scholarly journals Numerical simulation of star formation in filamentary dark molecular clouds

2015 ◽  
Vol 11 (S315) ◽  
pp. 103-106
Author(s):  
Pak Shing Li ◽  
Richard I. Klein ◽  
Christopher F. McKee
Keyword(s):  
Magnetic Field ◽  
Star Formation ◽  
Numerical Simulations ◽  
Adaptive Mesh Refinement ◽  
Molecular Clouds ◽  
Dynamic Range ◽  
Adaptive Mesh ◽  
Mass Function ◽  
Dark Cloud ◽  
Scale Down

AbstractNumerical simulations of star formation faces challenges including the huge spatial dynamic range and the presence of multiply coupled highly non-linear physics, such as magnetic field, supersonic turbulence, gravitation, radiation and protostellar outflow feedback. We present in this symposium our latest high resolution adaptive mesh refinement numerical simulations of the formation of filamentary dark molecular clouds from 4.55 pc size scale down to the formation of a protostellar cluster with maximum resolution at 28 AU. The physical properties of the long braided filamentary dark cloud formed in the simulation, the magnetic field properties of the cloud clumps, and the protostellar mass function in the simulations match well with the latest observations.

scholarly journals Numerical Simulations of Collapse of a Magnetized Rotating Molecular Cloud

1994 ◽  
Vol 140 ◽  
pp. 280-281
Author(s):  
Kanji Ohta ◽  
Asao Habe
Keyword(s):  
Magnetic Field ◽  
Star Formation ◽  
Numerical Simulations ◽  
Formation Process ◽  
Molecular Cloud ◽  
Molecular Clouds ◽  
Star Forming ◽  
Star Forming Regions ◽  
The Magnetic Field ◽  
Collapse Process

Recent observations reveal the velocity structure of star forming regions and the magnetic field in molecular clouds. It is known from observations that the molecular clouds rotate. It is suggested that the magnetic field have a important roll of the star formation process (e.g. Myers and Goodman 1988) and rotation of cloud have effects for evolution of molecular cloud. However it is not cleared how the magnetic field plays a roll of the star formation process in a rotating cloud.In the previous theoretical studies, most of simulations are performed for collapse process of a rotating cloud without magnetic field (e.g. Miyama et al. 1984, Boss 1990) or collapse process of a magnetized cloud without rotation (e.g. Scott and Black 1980). Dorfi (1982) studied collapse of a magnetized, rotating cloud. However he did not calculate those with high resolutions, since he performed 3-dimensional calculations of about 6000 grid points.Since observation instruments have been developed, it is possible to observe the star forming regions with good resolution. We study the collapse of the rotating, magnetized, isothermal cloud by mean of the axisymmetric numerical simulations with high resolution.

scholarly journals The Formation and Destruction of Molecular Clouds and Galactic Star Formation

2015 ◽  
Vol 11 (S315) ◽  
pp. 61-68
Author(s):  
Shu-ichiro Inutsuka ◽  
Tsuyoshi Inoue ◽  
Kazunari Iwasaki ◽  
Takashi Hosokawa ◽  
Masato I. N. Kobayashi
Keyword(s):  
Star Formation ◽  
Molecular Cloud ◽  
Molecular Clouds ◽  
Massive Stars ◽  
Age Determination ◽  
Mass Function ◽  
Mass Star ◽  
Nearby Star ◽  
Star Forming ◽  
Star Forming Regions

AbstractWe discuss an overall picture of star formation in the Galaxy. Recent high-resolution magneto-hydrodynamical simulations of two-fluid dynamics with cooling/heating and thermal conduction have shown that the formation of molecular clouds requires multiple episodes of supersonic compression. This finding enables us to create a new scenario of molecular cloud formation through interacting shells or bubbles on galactic scales. We estimate the ensemble-averaged growth rate of individual molecular clouds, and predict the associated cloud mass function. This picture naturally explains the accelerated star formation over many million years that was previously reported by stellar age determination in nearby star forming regions. The recent claim of cloud-cloud collisions as a mechanism for forming massive stars and star clusters can be naturally accommodated in this scenario. This explains why massive stars formed in cloud-cloud collisions follows the power-law slope of the mass function of molecular cloud cores repeatedly found in low-mass star forming regions.

The role of the magnetic field in a translucent molecular cloud

2018 ◽  
Vol 14 (A30) ◽  
pp. 108-108
Author(s):  
Georgia Panopoulou
Keyword(s):  
Magnetic Field ◽  
Molecular Cloud ◽  
Quantitative Estimate ◽  
Molecular Clouds ◽  
Dust Emission ◽  
Field Orientation ◽  
Magnetic Field Orientation ◽  
Cloud Evolution ◽  
The Magnetic Field

AbstractTranslucent molecular clouds represent a vastly underexplored regime of cloud evolution in terms of the effect of the magnetic field. Their pristine nature renders them ideal for investigating the initial properties of the magnetic field, prior to the onset of star formation. Using starlight polarimetry, we map the plane-of-sky magnetic field orientation throughout 10 sq. degrees of the Polaris Flare translucent molecular cloud. We provide the first quantitative estimate of the magnetic field strength in this type of system. By combining our measurements with the high-resolution Herschel dust emission map, we find a preferred alignment between filaments and the observed magnetic field. Our results support the presence of a strong magnetic field in this system (Panopoulou et al. 2016).

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