The Large Variable Magnetic Field of HD 126515 and its Implications for the Rigid-Rotator Model of Magnetic Stars

1970 ◽  
Vol 160 ◽  
pp. 1059 ◽  
Author(s):  
George W. Preston
1976 ◽  
Vol 32 ◽  
pp. 233-254
Author(s):  
H. M. Maitzen

Ap stars are peculiar in many aspects. During this century astronomers have been trying to collect data about these and have found a confusing variety of peculiar behaviour even from star to star that Struve stated in 1942 that at least we know that these phenomena are not supernatural. A real push to start deeper theoretical work on Ap stars was given by an additional observational evidence, namely the discovery of magnetic fields on these stars by Babcock (1947). This originated the concept that magnetic fields are the cause for spectroscopic and photometric peculiarities. Great leaps for the astronomical mankind were the Oblique Rotator model by Stibbs (1950) and Deutsch (1954), which by the way provided mathematical tools for the later handling pulsar geometries, anti the discovery of phase coincidence of the extrema of magnetic field, spectrum and photometric variations (e.g. Jarzebowski, 1960).


2021 ◽  
Author(s):  
Yury Belousov ◽  
Roberto Grimaudo ◽  
Antonino Messina ◽  
Agostino Migliore ◽  
Alessandro Sergi

2021 ◽  
Author(s):  
Noor Wali Khan ◽  
Arshad Khan ◽  
Muhammad Usman ◽  
Taza Gul ◽  
Abir Mouldi ◽  
...  

Abstract The investigations about thin-film flow play a vital role in the field of optoelectronics and magnetic devices. Thin films are reasonably hard and thermally stable but are more fragile. The thermal stability of thin film can be further improved by incorporating the effects of nanoparticles. In the current work, a stretchable surface is considered upon which hybrid nanofluid thin-film flow is taken into account. The idea of augmenting heat transmission is focused in current work by making use of hybrid nanofluid. The flow is affected by variations in the viscous forces along with viscous dissipation effects and Marangoni convection. A time-constrained magnetic field is applied in the normal direction to the flow system. The equations governing the flow system are shifted to a non-dimensional form by applying similarity variables. The homotopy analysis method (HAM) has been employed to find the solution of resultant equations. It has been noticed in this study that, the flow characteristics decline with augmentation in magnetic, viscosity, and unsteadiness parameters while grow up with enhancing values of thin-film parameter. Thermal characteristics are supported by the growing values of the Eckert number and unsteadiness parameter while opposed by the viscosity parameter and Prandtl number. The numerical impact of different emerging parameters upon skin friction and Nusselt number has been calculated in tabular form. A comparison of current work with established result has carried out with a good agreement in both results.


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