The angular momentum problem during star formation Magnetically linked, aligned rotators. I - an exact, time-dependent solution

1985 ◽  
Vol 298 ◽  
pp. 190 ◽  
Author(s):  
T. Ch. Mouschovias ◽  
S. A. Morton
Keyword(s):  
Angular Momentum ◽  
Star Formation ◽  
Time Dependent ◽  
Exact Time ◽  
Time Dependent Solution

Time-dependent solution of the logistic model for population growth in random environment

1980 ◽  
Vol 17 (04) ◽  
pp. 1083-1086
Author(s):  
Prajneshu
Keyword(s):  
Population Growth ◽  
Stationary Solution ◽  
Random Environment ◽  
Carrying Capacity ◽  
Logistic Model ◽  
Time Dependent ◽  
Kolmogorov Equation ◽  
Exact Time ◽  
Time Dependent Solution

The exact time-dependent solution as well as the stationary solution of the logistic model for population growth with varying carrying capacity is worked out in both the Stratonovich and Ito calculi by solving the forward Kolmogorov equation.

scholarly journals The Role of Magnetic Fields in the Formation of Stars

1981 ◽  
Vol 93 ◽  
pp. 27-62 ◽  
Author(s):  
Telemachos Ch. Mouschovias
Keyword(s):  
Magnetic Field ◽  
Angular Momentum ◽  
Star Formation ◽  
Magnetic Fields ◽  
Gravitational Collapse ◽  
Ambipolar Diffusion ◽  
Time Dependent ◽  
Interstellar Clouds ◽  
Critical States

We review the role of the interstellar magnetic field: (i) in the formation of interstellar clouds; (ii) in determining critical states for gravitational collapse; (iii) in affecting the collapse and fragmentation of interstellar clouds; and (iv) in resolving the “angular momentum problem” during star formation. Finally, we review the manner in which the field decouples from the matter via ambipolar diffusion; new time-dependent solutions are discussed.

Ideally conducting magnetostatic equilibria and associated time dependent, resistive flows

1971 ◽  
Vol 6 (1) ◽  
pp. 125-136 ◽  
Author(s):  
John C. Stevenson
Keyword(s):  
Magnetic Field ◽  
Energy Equation ◽  
Incompressible Flows ◽  
Neutral Point ◽  
Time Dependent ◽  
Two Dimensional ◽  
Exact Time ◽  
Field Lines ◽  
Time Dependent Solution ◽  
The Magnetic Field

Several types of two-dimensional solutions for the equations of magnetohydrodynamics are described. For all these solutions the magnetic field contains at least one hyperbolic neutral point. Two new magnetostatic equilibria are introduced for the ideally conducting case. The magnetic field associated with one of these is used to construct an exact time-dependent solution of the MilD equations where the fluid is necessarily at rest. In the case where the field lines are hyperbolae, it is demonstrated that retention of the energy equation (ordinarily decoupled for incompressible flows) implies that the flow beginning at rest, remains at trest

Time-dependent solution of the logistic model for population growth in random environment

1980 ◽  
Vol 17 (4) ◽  
pp. 1083-1086 ◽  
Author(s):  
Prajneshu
Keyword(s):  
Population Growth ◽  
Stationary Solution ◽  
Random Environment ◽  
Carrying Capacity ◽  
Logistic Model ◽  
Time Dependent ◽  
Kolmogorov Equation ◽  
Exact Time ◽  
Time Dependent Solution

The exact time-dependent solution as well as the stationary solution of the logistic model for population growth with varying carrying capacity is worked out in both the Stratonovich and Ito calculi by solving the forward Kolmogorov equation.

scholarly journals Effects of initial density profiles on massive star cluster formation in giant molecular clouds

2021 ◽  
Author(s):  
Yingtian Chen ◽  
Hui Li ◽  
Mark Vogelsberger
Keyword(s):  
Angular Momentum ◽  
Star Formation ◽  
Molecular Clouds ◽  
Globular Clusters ◽  
Cluster Formation ◽  
Initial Density ◽  
Giant Molecular Clouds ◽  
Density Profiles ◽  
Stellar Feedback ◽  
Gas Accretion

Abstract We perform a suite of hydrodynamic simulations to investigate how initial density profiles of giant molecular clouds (GMCs) affect their subsequent evolution. We find that the star formation duration and integrated star formation efficiency of the whole clouds are not sensitive to the choice of different profiles but are mainly controlled by the interplay between gravitational collapse and stellar feedback. Despite this similarity, GMCs with different profiles show dramatically different modes of star formation. For shallower profiles, GMCs first fragment into many self-gravitation cores and form sub-clusters that distributed throughout the entire clouds. These sub-clusters are later assembled ‘hierarchically’ to central clusters. In contrast, for steeper profiles, a massive cluster is quickly formed at the center of the cloud and then gradually grows its mass via gas accretion. Consequently, central clusters that emerged from clouds with shallower profiles are less massive and show less rotation than those with the steeper profiles. This is because 1) a significant fraction of mass and angular momentum in shallower profiles is stored in the orbital motion of the sub-clusters that are not able to merge into the central clusters 2) frequent hierarchical mergers in the shallower profiles lead to further losses of mass and angular momentum via violent relaxation and tidal disruption. Encouragingly, the degree of cluster rotations in steeper profiles is consistent with recent observations of young and intermediate-age clusters. We speculate that rotating globular clusters are likely formed via an ‘accretion’ mode from centrally-concentrated clouds in the early Universe.

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