Critical Rotation Rate for Vortex Nucleation in Ultracold Rotating Boson Atoms Trapped in 2D Deep Optical Lattice at Finite Temperature

2020 ◽  
Vol 200 (3-4) ◽  
pp. 102-117
Author(s):  
Ahmed S. Hassan ◽  
Azza M. Elbadry ◽  
Alyaa A. Mahmoud ◽  
A. M. Mohammedein ◽  
A. M. Abdallah
Keyword(s):  
Rotation Rate ◽  
Finite Temperature ◽  
Optical Lattice ◽  
Critical Rotation ◽  
Vortex Nucleation

The Evolution of Rapidly Rotating B/Be Stars

1982 ◽  
Vol 98 ◽  
pp. 299-302 ◽  
Author(s):  
A. S. Endal
Keyword(s):  
Rotation Rate ◽  
Main Sequence ◽  
Critical Value ◽  
Moment Of Inertia ◽  
Maxwellian Distribution ◽  
Be Stars ◽  
Rotating Stars ◽  
Hydrogen Burning ◽  
Critical Rotation ◽  
The Moment

Rotation can significantly change the moment-of-inertia of a main sequence star. As a result, the ZAMS rotation rate need only be within ~30% of the critical value in order to reach critical rotation during the hydrogen burning stage. Calculations of the evolution of rotating stars show that the Be stars result from a normal (Maxwellian) distribution of B-star rotation velocities.

scholarly journals Spherical vortices in rotating fluids

2018 ◽  
Vol 846 ◽  
Author(s):  
M. M. Scase ◽  
H. L. Terry
Keyword(s):  
Ideal Fluid ◽  
Rotation Rate ◽  
Wave Motion ◽  
Infinite Family ◽  
Vortex Rings ◽  
Rotating Fluids ◽  
Critical Rotation ◽  
Spherical Vortex ◽  
Inertial Wave ◽  
Special Case

A popular model for a generic fat-cored vortex ring or eddy is Hill’s spherical vortex (Phil. Trans. R. Soc. A, vol. 185, 1894, pp. 213–245). This well-known solution of the Euler equations may be considered a special case of the doubly infinite family of swirling spherical vortices identified by Moffatt (J. Fluid Mech., vol. 35 (1), 1969, pp. 117–129). Here we find exact solutions for such spherical vortices propagating steadily along the axis of a rotating ideal fluid. The boundary of the spherical vortex swirls in such a way as to exactly cancel out the background rotation of the system. The flow external to the spherical vortex exhibits fully nonlinear inertial wave motion. We show that above a critical rotation rate, closed streamlines may form in this outer fluid region and hence carry fluid along with the spherical vortex. As the rotation rate is further increased, further concentric ‘sibling’ vortex rings are formed.

scholarly journals Applegate mechanism in post-common-envelope binaries: Investigating the role of rotation

2018 ◽  
Vol 615 ◽  
pp. A81 ◽  
Author(s):  
F. H. Navarrete ◽  
D. R. G. Schleicher ◽  
J. Zamponi Fuentealba ◽  
M. Völschow
Keyword(s):  
Orbital Period ◽  
Rotation Rate ◽  
Main Sequence ◽  
Magnetic Activity ◽  
Main Sequence Star ◽  
Common Envelope ◽  
Rotation Rates ◽  
Critical Rotation ◽  
Period Variations ◽  
Time Variations

Context. Eclipsing time variations are observed in many close binary systems. In particular, for several post-common-envelope binaries (PCEBs) that consist of a white dwarf and a main sequence star, the observed-minus-calculated (O–C) diagram suggests that real or apparent orbital period variations are driven by Jupiter-mass planets or as a result of magnetic activity, the so-called Applegate mechanism. The latter explains orbital period variations as a result of changes in the stellar quadrupole moment due to magnetic activity. Aims. In this work we explore the feasibility of driving eclipsing time variations via the Applegate mechanism for a sample of PCEB systems, including a range of different rotation rates. Methods. We used the MESA code to evolve 12 stars with different masses and rotation rates. We applied simple dynamo models to their radial profiles to investigate the scale at which the predicted activity cycle matches the observed modulation period, and quantifiy the uncertainty. We further calculated the required energies to drive the Applegate mechanism. Results. We show that the Applegate mechanism is energetically feasible in 5 PCEB systems. In RX J2130.6+4710, it may be feasible as well considering the uncertainties. We note that these are the systems with the highest rotation rate compared to the critical rotation rate of the main-sequence star. Conclusions. The results suggest that the ratio of physical to critical rotation rate in the main sequence star is an important indicator for the feasibility of Applegate’s mechanism, but exploring larger samples will be necessary to probe this hypothesis.

scholarly journals Critical velocity for vortex nucleation in a finite-temperature Bose gas

2016 ◽  
Vol 93 (2) ◽  
Author(s):  
G. W. Stagg ◽  
R. W. Pattinson ◽  
C. F. Barenghi ◽  
N. G. Parker
Keyword(s):  
Critical Velocity ◽  
Finite Temperature ◽  
Bose Gas ◽  
Vortex Nucleation

scholarly journals Results from a recent stellar rotation census of B stars

2010 ◽  
Vol 6 (S272) ◽  
pp. 89-90
Author(s):  
Wenjin Huang ◽  
Douglas R. Gies ◽  
M. Virginia McSwain
Keyword(s):  
Effective Temperature ◽  
Rotation Rate ◽  
Rotation Speed ◽  
Rotational Velocity ◽  
Rotation Velocity ◽  
Be Stars ◽  
Stellar Rotation ◽  
B Stars ◽  
Critical Rotation ◽  
Critical Rotation Speed

AbstractIn an analysis of the rotational properties of more than 1100 B stars (~660 cluster and ~500 field B stars), we determine the projected rotational velocity (V sin i), effective temperature, gravity, mass, and critical rotation speed for each star. The new data provide us a solid observational base to explore many hot topics in this area: Why do field B stars rotate slower than cluster B stars? How fast do B stars rotate when they are just born? How fast can B stars rotate before they become Be stars? How does the rotation rate of B stars change with time? Does the evolutionary change in rotation velocity lead to the Be phenomenon? Here we report the results of our efforts in searching for answers to these questions based on the latest B star census.

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