Topic
Rotation
About: Rotation is a research topic. Over the lifetime, 84289 publications have been published within this topic receiving 599685 citations. The topic is also known as: spinning & rotary motion.
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TL;DR: In this article, a generalized model for the spherical collapse of a singular isothermal sphere such as protosolar and binary nebulae is defined for a sound speed of 0.35 km/sec and a rotation rate of 10 to 14th/sec.
Abstract: A generalized model which accounts for the effects of initially uniform and slow rotation is defined for the spherical collapse of a singular isothermal sphere such as protosolar and binary nebulae. An initial unstable equilibrium state is described for a sound speed of 0.35 km/sec and a rotation rate of 10 to the -14th/sec for the molecular cloud surrounding the accreting core. The total angular momentum and mass of the inner cloud is set equal to solar system values. The evolution of the collapse is traced by applying a perturbation analysis to the similarity solution for a nonrotating condition, and matched asymptotic expansions solve the hydrodynamic equations. The model is concluded a valid tool for studying star and nebular disk formation.
673 citations
TL;DR: In this paper, the authors demonstrate that spin-transfer torques occur in magnetic heterostructures because the transverse component of a spin current that flows from a nonmagnet into a ferromagnet is absorbed at the interface.
Abstract: Spin-transfer torques occur in magnetic heterostructures because the transverse component of a spin current that flows from a nonmagnet into a ferromagnet is absorbed at the interface. We demonstrate this fact explicitly using free-electron models and first-principles electronic structure calculations for real material interfaces. Three distinct processes contribute to the absorption: (1) spin-dependent reflection and transmission, (2) rotation of reflected and transmitted spins, and (3) spatial precession of spins in the ferromagnet. When summed over all Fermi surface electrons, these processes reduce the transverse component of the transmitted and reflected spin currents to nearly zero for most systems of interest. Therefore, to a good approximation, the torque on the magnetization is proportional to the transverse piece of the incoming spin current.
670 citations
TL;DR: In this article, a Sagnac-effect atom interferometer gyroscope using stimulated Raman transitions was used to coherently manipulate atomic wave packets, measured the Earth's rotation rate and demonstrated a short-term sensitivity to rotations of $2.
Abstract: We report the demonstration of a Sagnac-effect atom interferometer gyroscope which uses stimulated Raman transitions to coherently manipulate atomic wave packets. We have measured the Earth's rotation rate, and demonstrated a short-term sensitivity to rotations of $2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}(\mathrm{rad}/\mathrm{s})/\sqrt{\mathrm{Hz}}$.
661 citations
661 citations
TL;DR: The constancy of frequency in the recently discovered pulsed radio sources can be accounted for by the rotation of a neutron star as discussed by the authors, where relativistic velocities will set up in any plasma in the surrounding magnetosphere, leading to radiation in the pattern of a rotating beacon.
Abstract: The constancy of frequency in the recently discovered pulsed radio sources can be accounted for by the rotation of a neutron star. Because of the strong magnetic fields and high rotation speeds, relativistic velocities will be set up in any plasma in the surrounding magnetosphere, leading to radiation in the pattern of a rotating beacon.
651 citations