Magnetic fields in white dwarfs and stellar evolution     

Christopher A. Tout  Dayal T. Wickramasinghe  Lilia Ferrario 《Monthly notices of the Royal Astronomical Society》2004,355(3):L13-L16

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New limits on the generation of magnetic fields     

Leonid Chuzhoy 《Monthly notices of the Royal Astronomical Society》2004,350(2):761-762

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Magnetic field in the intracluster medium: Rydberg matter with almost free electrons     

Shahriar Badiei  Leif Holmlid 《Monthly notices of the Royal Astronomical Society》2002,335(4):L94-L98

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Magnetic fields in cometary globules – III. CG 12     

H. C. Bhatt  G. Maheswar  P. Manoj 《Monthly notices of the Royal Astronomical Society》2004,348(1):83-88

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Cosmic ray acceleration to very high energy through the non-linear amplification by cosmic rays of the seed magnetic field     

A. R. Bell  S. G. Lucek 《Monthly notices of the Royal Astronomical Society》2001,321(3):433-438

The maximum energy for cosmic ray acceleration at supernova shock fronts is usually thought to be limited to around 10¹⁴–10¹⁵ eV by the size of the shock and the time for which it propagates at high velocity. We show that the magnetic field can be amplified non-linearly by the cosmic rays to many times the pre-shock value, thus increasing the acceleration rate and facilitating acceleration to energies well above 10¹⁵ eV. A supernova remnant expanding into a uniform circumstellar medium may accelerate protons to 10¹⁷ eV and heavy ions, with charge Ze , to Z ×10¹⁷ eV. Expansion into a pre-existing stellar wind may increase the maximum cosmic ray energy by a further factor of 10.  相似文献   

Calculating the potential magnetic field of a local region on the Sun using the measured oblique component     

O. G. Den 《Astronomy Letters》2002,28(5):345-352

We propose a method for solving the Neumann boundary-value problem using the known magnetic-field component at the boundary in a specified direction (the oblique-derivative problem). The method allows the normal field component at the boundary to be directly determined from the measured line-of-sight component. This makes it possible to calculate the potential magnetic field in the corona above a region far removed from the solar-disk center. A model potential magnetic field is used as an example to test our method.  相似文献   

Effects of activity complexes and active longitudes on variations in total solar irradiance     

A. V. Mordvinov  R. C. Willson 《Astronomy Letters》2001,27(7):451-454

A numerical technique of time-longitude analysis has been developed by studying the fine structure of temporal variations in total solar irradiance (TSI). This analysis produces maps of large-scale thermal inhomogeneities on the Sun and reveals corresponding patterns of radiative excess and deficit relative to the unperturbed solar photosphere. These patterns are organized in two-and four-sector structures and exhibit the effects of both activity complexes and the active longitudes. Large-scale patterns with radiative excess show a facular macrostructure caused by the relaxation of large-scale thermo-magnetic perturbations and/or energy output due to very large-scale solar convection. These thermal patterns are related to long-lived magnetic fields that are characterized by rigid rotation. The patterns with radiative excess tend to concentrate around the active longitudes and are centered at 103° and 277° in the Carrington system when averaged over the time-longitude distribution of thermal inhomogeneities during activity cycles 21–23.  相似文献   

γ-ray burst internal shocks with magnetization     

Y. Z. Fan  D. M. Wei  Bing Zhang 《Monthly notices of the Royal Astronomical Society》2004,354(4):1031-1039

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Magnetic fields in massive stars: dynamics and origin     

James MacDonald  D. J. Mullan 《Monthly notices of the Royal Astronomical Society》2004,348(2):702-716

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On the time dependence of differential rotation in young late-type stars     

Antonino F. Lanza 《Monthly notices of the Royal Astronomical Society》2006,373(2):819-826

A model for the angular momentum transfer within the convection zone of a rapidly rotating star is introduced and applied to the analysis of recent observations of temporal fluctuations of the differential rotation on the young late-type stars AB Doradus (AB Dor) and LQ Hydrae (LQ Hya). Under the hypothesis that the mean magnetic field produced by the stellar dynamo rules the angular momentum exchanges and that the angular velocity depends only on the distance s from the rotation axis and the time, the minimum azimuthal Maxwell stress  | B_sB _φ|  , averaged over the convection zone, is found to range from ∼0.04 to  ∼0.14 T²  . If the poloidal mean magnetic field   B _s   is of the order of 0.01 T, as indicated by the Zeeman–Doppler imaging maps of those stars, then the azimuthal mean field   B _φ  can reach an intensity of several teslas, which significantly exceeds equipartition with the turbulent kinetic energy. Such strong fields can account also for the orbital period modulation observed in cataclysmic variables and RS Canum Venaticorum systems with a main-sequence secondary component. Moreover, the model allows us to compute the kinetic energy dissipation rate during the maintenance of the differential rotation. Only in the case of the largest surface shear observed on LQ Hya may the dissipated power exceed the stellar luminosity, but the lack of a sufficient statistic on the occurrence of such episodes of large shear does not allow us to estimate their impact on the energy budget of the convection zone.  相似文献