Precessing spherical shells: flows, dissipation, dynamo and the lunar core
نویسندگان
چکیده
منابع مشابه
Persistence and origin of the lunar core dynamo.
The lifetime of the ancient lunar core dynamo has implications for its power source and the mechanism of field generation. Here, we report analyses of two 3.56-Gy-old mare basalts demonstrating that they were magnetized in a stable and surprisingly intense dynamo magnetic field of at least ~13 μT. These data extend the known lifetime of the lunar dynamo by ~160 My and indicate that the field wa...
متن کاملBistable flows in precessing spheroids
Precession driven flows are found in any rotating container filled with liquid, when the rotation axis itself rotates about a secondary axis that is fixed in an inertial frame of reference. Because of its relevance for planetary fluid layers, many works consider spheroidal containers, where the uniform vorticity component of the bulk flow is reliably given by the well-known equations obtained b...
متن کاملThe Case Against an Early Lunar Dynamo Powered by Core Convection
Paleomagnetic analyses of lunar samples indicate that the Moon had a dynamo-generated magnetic field with ~50 μT surface field intensities between 3.85 and 3.56 Ga followed by a period of much lower (≤ ~5 μT) intensities that persisted beyond 2.5 Ga. However, we determine herein that there is insufficient energy associated with core convection—the process commonly recognized to generate long-li...
متن کاملA Spherical Plasma Dynamo Experiment
We propose a plasma experiment to be used to investigate fundamental properties of astrophysical dynamos. The highly conducting, fast flowing plasma will allow experimenters to explore the high-magnetic-Reynolds-number regime. The plasma is confined using a ring-cusp strategy and subject to a toroidal differentially rotating outer boundary condition. As proof of principle, we present magnetohyd...
متن کاملNematic textures in spherical shells.
The equilibrium texture of nematic shells is studied as a function of their thickness. For ultrathin shells the ground state has four short 1/2 disclination lines but, as the thickness of the film increases, a three-dimensional escaped configuration composed of two pairs of half-hedgehogs becomes energetically favorable. We derive an exact solution for the nematic ground state in the one Frank ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Geophysical Journal International
سال: 2019
ISSN: 0956-540X,1365-246X
DOI: 10.1093/gji/ggz037