نتایج جستجو برای: sun: magnetic elds

تعداد نتایج: 373739  

Journal: :iranian journal of astronomy and astrophysics 2015
akram gheidi shahran taghi mirtorabi

distribution of magnetic fields in the quiet-sun internetwork areas has been affected by weak polarization (in particular stokes q and u) signals. to improve the signal-to-noise ratio (snr) of the weak polarization signals, several approaches, including temporal integrations, have been proposed in the literature. in this study, we aim to investigate a proper temporal-integration time with which...

Akram Gheidi Shahran Taghi Mirtorabi

Distribution of magnetic fields in the quiet-Sun internetwork areas has been affected by weak polarization (in particular Stokes Q and U) signals. To improve the signal-to-noise ratio (SNR) of the weak polarization signals, several approaches, including temporal integrations, have been proposed in the literature. In this study, we aim to investigate a proper temporal-integration time with which...

2007
M. F. WOODARD JONGCHUL CHAE

A comparison of BBSO H centerline ltergrams and videomagnetograms was made to investigate the existence of non-potential magnetic elds in the quiet Sun near magnetic network. We use the bril structure in the H images as a proxy for the horizontal chromospheric magnetic eld which we compare with the horizontal eld obtained by potential extrapolation of the observed, line-of-sight photospheric el...

2007
J. P. Cassinelli K. B. MacGregor

We explore the possibility that the magnetic eld generated by a dynamo at the interface between the convective core and radiative envelope of a massive star can be transported to the surface by buoyancy. 1. Application of solar ux tube theory to massive stars Among the topics receiving attention at the present meeting has been the possible role of magnetic elds in producing some of the phenomen...

2003
David J. Stevenson

The past several years have seen dramatic developments in the study of planetary magnetic fields, including a wealth of new data, mainly from the Galilean satellites and Mars, together with major improvements in our theoretical modeling effort of the dynamo process believed responsible for large planetary fields. These dynamos arise from thermal or compositional convection in fluid regions of l...

2004
Jens Wendler

Data on the relation of past climate variations and changes in the geomagnetic +eld can contribute to the research on a cosmic ray–climate link. This paper presents a synthesis of geological and astrophysical results about the link of magnetic +eld variations and Earth’s climate and external forcing. On millennial timescales, geomagnetic intensity lows are apparently in phase with times of low ...

2008
Nir J. Shaviv Jeremy S. Heyl Yoram Lithwick

Extremely strong magnetic elds change the vacuum index of refraction. This induces a lensing eeect that is not unlike the lensing phenomenon in strong gravitational elds. The main diierence between the two is the polarization dependency of the magnetic lensing, a behaviour that induces a handful of interesting eeects. The main prediction is that the thermal emission of neutron stars with extrem...

2007
Russell M. Kulsrud Renyue Cen Jeremiah P. Ostriker Dongsu Ryu

It is demonstrated that strong magnetic elds are produced from a zero initial magnetic eld during the pregalactic era, when galaxies are rst forming. Their development proceeds in three phases. In the rst phase, weak magnetic elds are created by the Biermann battery mechanism, acting in shocked parts of the intergalactic medium where caustics form and intersect. In the second phase, these weak ...

2007
G. H. FISHER

1. Abstract We describe some of our recent work on the dynamics of ux tubes in the solar convection zone. We focus on two topics, the rst being the orientation (\tilt") of active regions, and how comparisons between observations of tilt and tilts computed from numerical simulations of ux tubes can be used to infer properties of magnetic elds deep in the solar interior. The second topic is an in...

2007
Yue-Hua Ma

It is analysed the discrepancy about the coronal magnetic eld between solar optic and solar radio using magnetic bril concept with lling factor and fractal structure model. The magnetic eld of 100 G considered in solar optics is mean value in a large scale, and that of 1000 G in solar should be the value of ne structures inside \macro" loop. The magnetic eld in the solar corona is poorly known ...

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