The Formation of a Cluster of Stars and Brown Dwarfs in a Turbulent Molecular Cloud

2006 ◽  
pp. 139-146
Author(s):  
Matthew R. Bate ◽  
Ian A. Bonnell ◽  
Volker Bromm
Keyword(s):  
Molecular Cloud ◽  
Brown Dwarfs

Modeling the Protoplanetary Disks of Two Brown Dwarfs in the Taurus Molecular Cloud

2019 ◽  
Vol 878 (2) ◽  
pp. 103 ◽  
Author(s):  
Anneliese M. Rilinger ◽  
Catherine C. Espaillat ◽  
Enrique Macías
Keyword(s):  
Molecular Cloud ◽  
Protoplanetary Disks ◽  
Brown Dwarfs ◽  
Taurus Molecular Cloud

scholarly journals Theory of Young Clusters

2004 ◽  
Vol 221 ◽  
pp. 257-264
Author(s):  
Matthew R. Bate ◽  
Ian A. Bonnell
Keyword(s):  
Star Formation ◽  
Molecular Cloud ◽  
Initial Conditions ◽  
Star Clusters ◽  
Brown Dwarfs ◽  
Mass Function ◽  
Large Cluster ◽  
Close Binaries ◽  
Stellar Clusters ◽  
Small Clusters

We review recent results from hydrodynamical calculations of the formation of young stellar clusters. The calculations present a highly dynamical picture of star formation where the mass function of stars originates from competitive accretion between protostars and dynamical ejections which halt accretion. Large star clusters form hierarchically; a molecular cloud forms many small clusters that later merge into one large cluster, erasing the initial substructure. Using calculations that resolve fragmentation down to the opacity limit, we examine the implications of dynamical star formation for the IMF, the formation of brown dwarfs and close binaries, and the sizes of protoplanetary discs. Finally, we discuss the dependence of the results on the initial conditions.

scholarly journals On The Formation of Brown Dwarfs

2004 ◽  
Vol 191 ◽  
pp. 227-231
Author(s):  
Ing-Guey Jiang ◽  
G. Laughlin ◽  
D.N.C. Lin
Keyword(s):  
Star Formation ◽  
Binary Stars ◽  
Large Distance ◽  
Molecular Cloud ◽  
Brown Dwarfs ◽  
Dynamical Interaction ◽  
Interstellar Clouds ◽  
Secondary Fragmentation ◽  
Fragmentation Processes ◽  
Cloud Core

AbstractThe observational properties of brown dwarfs pose challenges to the theory of star formation. Because their masses are much smaller than the typical Jeans mass of interstellar clouds, brown dwarfs are most likely formed through secondary fragmentation processes, rather than through the direct collapse of a molecular cloud core. In order to prevent substantial post-formation mass accretion, young brown dwarfs must leave the high-density formation regions in which they form. We propose here that brown dwarfs are formed in the optically thin outer regions of circumbinary disks. Through post-formation dynamical interaction with their host binary stars, young brown dwarfs are either scattered to large distance or removed, with modest speed, from their cradles.

scholarly journals New Young Brown Dwarfs in the Orion Molecular Cloud 2/3 Region

2008 ◽  
Vol 685 (1) ◽  
pp. 313-332 ◽  
Author(s):  
Dawn E. Peterson ◽  
S. T. Megeath ◽  
K. L. Luhman ◽  
J. L. Pipher ◽  
J. R. Stauffer ◽  
...  
Keyword(s):  
Molecular Cloud ◽  
Brown Dwarfs

scholarly journals A U-band survey of brown dwarfs in the Taurus molecular cloud with the XMM-Newton optical/UV monitor

2006 ◽  
Vol 468 (2) ◽  
pp. 557-562 ◽  
Author(s):  
N. Grosso ◽  
M. Audard ◽  
J. Bouvier ◽  
K. R. Briggs ◽  
M. Güdel
Keyword(s):  
Molecular Cloud ◽  
Brown Dwarfs ◽  
Band Survey ◽  
Taurus Molecular Cloud

scholarly journals A Search for Optical Outflows from Brown Dwarfs in the Chamaeleon I Molecular Cloud

2006 ◽  
Vol 643 (2) ◽  
pp. 985-994 ◽  
Author(s):  
Hongchi Wang ◽  
Thomas Henning
Keyword(s):  
Molecular Cloud ◽  
Brown Dwarfs

Constraints on the formation of brown dwarfs by turbulent compression

2019 ◽  
Vol 488 (2) ◽  
pp. 2644-2649
Author(s):  
Torsten Stamer ◽  
Shu-ichiro Inutsuka
Keyword(s):  
Turbulent Flows ◽  
Molecular Cloud ◽  
Brown Dwarfs ◽  
High Density ◽  
Compression Process ◽  
External Compression ◽  
Order Of Magnitude ◽  
Low Mass ◽  
Hydrodynamical Simulations ◽  
Cloud Core

ABSTRACT We perform radiation hydrodynamical simulations in spherical symmetry in order to investigate the formation of very low mass objects, i.e. brown dwarfs, by external compression. According to the Jeans stability criterion, a very low mass molecular cloud core must reach a very high density in order to become gravitationally unstable. One possibility to create such a high density is the compression by turbulent flows within the larger molecular cloud. Using our self-developed radiation hydrodynamics code, we aim to test the validity of this scenario, and to constrain the strength of the turbulence that is needed. We find that the probability for sufficiently strong and long-lived turbulence is very low under typical conditions even when using very optimistic assumptions, and therefore conclude that turbulent compression is unlikely to be the dominant mechanism for creating brown dwarfs. We also investigate the properties of objects formed by this turbulent compression process. Specifically, we compare the lifetime of the first core stage for the cases with and without external compression. We confirm our previous findings that the first core lifetime increases by about an order of magnitude at the extremely low-mass end, but this increase is somewhat less dramatic and occurs at even lower masses than in our previous work, in which no external compression was present.

scholarly journals Chemical Tracers of Pre-Brown Dwarf Cores Formed Through Turbulent Fragmentation

2015 ◽  
Vol 11 (S315) ◽  
Author(s):  
Jonathan Holdship ◽  
Serena Viti
Keyword(s):  
Molecular Cloud ◽  
Brown Dwarfs ◽  
Step Change ◽  
Time Dependent ◽  
Formation Mechanisms ◽  
Brown Dwarf ◽  
Star Forming ◽  
Chemical Tracers ◽  
Fractional Abundance ◽  
Chemical Code

AbstractA gas-grain time dependent chemical code, UCL_CHEM, has been used to investigate the possibility of using chemical tracers to differentiate between the possible formation mechanisms of brown dwarfs. We model the formation of a pre-brown dwarf core through turbulent fragmentation by following the depth-dependent chemistry in a molecular cloud through the step change in density associated with an isothermal shock and the subsequent freefall collapse once a bound core is produced. Trends in the fractional abundance of molecules commonly observed in star forming cores are then explored to find a diagnostic for identifying brown dwarf mass cores formed through turbulence. We find that the cores produced by our models would be bright in CO and NH3 but not in HCO+. This differentiates them from models using purely freefall collapse as such models produce cores that would have detectable transitions from all three molecules.

scholarly journals The Formation Mechanism and Resulting Properties of Brown Dwarfs

2003 ◽  
Vol 211 ◽  
pp. 27-30 ◽  
Author(s):  
Matthew R. Bate ◽  
Ian A. Bonnell ◽  
Volker Bromm
Keyword(s):  
Star Formation ◽  
Formation Mechanism ◽  
Binary Stars ◽  
Molecular Cloud ◽  
Large Scale ◽  
Brown Dwarfs ◽  
Circumstellar Disks ◽  
Mass Function ◽  
Initial Mass Function ◽  
Initial Mass

We present results from the most complex hydrodynamical star formation calculation performed to date. It follows the collapse and fragmentation of a large-scale turbulent molecular cloud to form dozens of stars and brown dwarfs. It resolves all fragmentation down to the opacity limit, binary stars with separations as small as 1 AU, and circumstellar disks with radii down to ≈ 10 AU. In this proceedings, we examine the formation mechanism of the brown dwarfs and compare the initial mass function and the properties of the brown dwarfs with observations.

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