An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 102 Search : magnetic
fossil magnetic field
  میدان ِ مغناتیسی ِ سنگواره، ~ ~ سنگواره‌ای   
meydân-e meqnâtisi-ye sangvâré, ~ ~ sangvâre-yi

Fr.: champ magnétique fossile   

In a physical system, the → magnetic field belonging to an earlier magnetic process or event. A fossil magnetic field may be a vanished one or exist in relic forms. As an example, the solar magnetic field, which was present during the formation of the Sun, has disappeared over the last 4.6 billions years.

fossil;→ magnetic; → field;

frozen magnetic field line
  خط ِ میدان ِ مغناتیسی ِ یخ‌بسته، ~ ~ ~ رچیده   
xatt-e meydân-e meqnâtisi-ye yax basté, ~ ~ ~ rocidé

Fr.: ligne de champ magnétique gelée   

A → magnetic field line in a → fluid when the motion of the fluid carries the magnetic field along with it.

Frozen, p.p. of → freeze; → magnetic; → line.

  زمین‌مغناتیسی، زمین‌مغناتی   
zamin-meqnâtisi, zamin-meqnâti

Fr.: géomagnétique   

Of or pertaining to → geomagnetism.

geo-; → magnetic.

geomagnetic activity
  ژیرندگی ِ زمین‌مغناتیسی، ~ زمین‌مغناتی   
žirandegi-ye zamin-meqnâtisi, ~ zamin-meqnâti

Fr.: activité géomagnétique   

The natural variations in the → geomagnetic field due to interactions of the Earth's field and → magnetosphere with energetic particles from the Sun.

geomagnetic; → activity.

geomagnetic excursion
  زچار ِ زمین‌مغناتی   
zocâr-e zamin-meqnâti

Fr.: excursion géomagnétique   

A geophysical event, distinguished from the → magnetic reversal, in which the Earth's magnetic field departs for a relatively short time from its usual near axial configuration, without establishing a reversed direction. During the excursion the intensity and direction of the Earth's magnetic field undergo drastic changes. Palaeomagnetic measurements have revealed that since the last full reversal the Earth's magnetic field has, for brief intervals, deviated from the behavior expected during "normal" secular variation.

geomagnetic; → excursion.

geomagnetic field
  میدان ِ زمین‌مغناتیسی، ~ زمین‌مغناتی   
meydân-e zamin-meqnâtisi, ~ zamin-meqnâti

Fr.: champ géomagnétique   

The magnetic field that is generated within the Earth and extends out around the Earth. The intensity of the magnetic field at the Earth's surface is about 0.32 → gauss at the equator and 0.62 gauss at the north pole.

geomagnetic; → field.

geomagnetic storm
  توفان ِ زمین‌مغناتیسی، ~ زمین‌مغناتی   
tufân-e zamin-meqnâtisi, ~ zamin-meqnâti

Fr.: orage géomagnétique   

A violent disturbance of the Earth's magnetic field, distinct from regular diurnal variations, following a → solar flare or → coronal mass ejection.

geomagnetic; → storm.


Fr.: hydromagnétisme   

Same as → magnetohydrodynamics.

hydro-; → magnetics.

interplanetary magnetic field
  میدان ِ مغناتیسی ِ اندرسیاره‌ای   
meydân-e meqnâtisi-ye andarsayyârei

Fr.: champ magnétique interstellaire   

The magnetic field that is carried along with the solar wind and fills the solar system space. It is wound into a spiral structure by the rotation of the Sun. At the Earth's distance from the Sun, it has a strength of about 5 x 10-5 gauss.

interplanetary; → magnetic; → field.

interstellar magnetic field
  میدان ِ مغناتیسی ِ اندر-اختری   
meydân-e meqnâtisi-ye andaraxtari

Fr.: champ magnétique interstellaire   

A large-scale, weak magnetic field, with an estimated strength of about 1 to 5 microgauss, that pervades the disk of the Milky Way Galaxy and controls the alignment of interstellar dust grains.

interstellar; → magnetic; → field.

longitudinal magnetic field
  میدان ِ مغناطیسی ِ درژنایی   
meydân-e meqnâtisi-ye derežnâyi

Fr.: champ magnétique longitudinal   

1) A → magnetic field whose lines of force (→ line of force) run parallel to the long axis of the → magnet. Longitudinal magnetization of a component can be accomplished using the longitudinal field set up by a → coil or → solenoid. It can also be accomplished using permanent magnets or electromagnets.
2) In → stellar magnetic field observations, the magnetic field along the → line of sight.

longitudinal; → magnetic; → field.

  مغناتیسی، مغناتی، آهنرباییک   
meqnâtisi (#), meqnâti, âhanrobâyik

Fr.: magnétique   

Of or pertaining to a magnet or magnetism.

From → magnet + → -ic.

Meqnâtisi, meqnâti, from meqnâtis, → magnet; âhanrobâyik, from âhanrobâ, → magnet, + → -ik, → -ic.

magnetic advection
  پهنبز ِ مغناتیسی   
pahnbaz-e meqnâtisi

Fr.: advection magnétique   

The transport of the magnetic field by a fluid. It is given by the term ∇ x (v x B) in the → induction equation.

magnetic; → advection.

magnetic axis
  آسه‌ی ِ مغناتیسی   
âse-ye meqnâtisi

Fr.: axe magnétique   

The imaginary straight line joining the two → poles of a → magnet.

magnetic; → meridian.

magnetic bottle
  بطری ِ مغناتیسی   
botri-ye meqnâtisi (#)

Fr.: bouteille magnétique   

Any configuration of → magnetic fields used in the containment of a → plasma during controlled → thermonuclear reaction experiments.

magnetic; → bottle.

magnetic braking
  لگامش ِ مغناتیسی   
legâmeš-e meqnâtisi

Fr.: freinage magnétique   

The process whereby a star which loses mass slows down under the action of its → magnetic field. The stellar material follows the → magnetic field lines extending well beyond the stellar surface. The material gain → angular momentum and the underlying object is slowed down. Magnetic braking is an efficient mechanism for removing angular momentum from the the rotating object. See also → disk locking.

magnetic; → braking.

magnetic braking catastrophe
  نگونزار ِ لگامش ِ مغناتیسی   
negunzâr-e legâmeš-e meqnâtisi

Fr.: catastrophe du freinage magnétique   

The failure of numerical star formation calculations to produce rotationally supported → Keplerian disks because of the → magnetic braking effect, when → magnetic fields of strengths comparable to those observed in → molecular clouds are accounted for. The formation and early evolution of disks is a long-standing fundamental problem in → star formation models. Early work in the field had concentrated on the simpler problem of disk formation from the → collapse of a rotating dense core in the absence of a magnetic field. However, dense star-forming cores are observed to be significantly magnetized. There is increasing theoretical evidence that disk formation is greatly modified, perhaps even suppressed, by a dynamically important magnetic field. This has been found in analytic studies, axisymmetric numerical models and in 3D calculations using → ideal magnetohydrodynamics. By contrast, recent observations suggest the presence of massive, 50-100 AU disks and evidence for associated → outflows in the earliest (→ class 0) stages of star formation around both low and high mass stars. Two primary solutions have been proposed: → turbulence and → non-ideal magnetohydrodynamics. Calculations of the collapse of a massive 100 Msun core have shown that 100 AU scale disk formation in the presence of strong magnetic fields was indeed possible, with some argument over whether this is caused by turbulent reconnection or another mechanism. Studies, using simulations of collapsing 5 Msun cores, have found that turbulence diffuses the strong magnetic field out of the inner regions of the core, and that the non-zero → angular momentum of the turbulence causes a misalignment between the rotation axis and the magnetic field. Both of these effects reduce the magnetic braking, and allow a massive disk to form (Wurster et al. 2016, arxiv/1512.01597 and references therein).

magnetic; → braking; → catastrophe.

magnetic bremsstrahlung
  لگام-تابش ِ مغناتیسی   
legâm-tâbeš-e meqâtisi

Fr.: rayonnement de freinage magnétique   

Same as → synchrotron radiation.

magnetic; → bremsstrahlung.

magnetic buoyancy
  بالارانی ِ مغناتیسی   
bâlârâni-ye meqnâtisi

Fr.: flottabilité magnétique   

The phenomenon whereby the presence of a → magnetic field can make a portion of → compressible fluid less dense than its surroundings, so that it floats upward under the influence of gravity. This magnetic buoyancy is thought, in fact, to be the mechanism by which magnetic flux tubes rise through the Sun's → convection zone and break at the surface in the form of → sunspots. The Sun's rotation would have a major effect on the rate at which these magnetic flux tubes rise. The rotation substantially lengthen the time taken for the flux tubes to reach the surface (D. J. Acheson, 1979, Nature 277, 41).

magnetic; → buoyancy.

magnetic cataclysmic binary
  دورین ِ گتلوری ِ مغناتیسی   
dorin-e gatluri-ye meqnâtisi

Fr.: binaire cataclysmique magnétique   

A cataclysmic binary in which the white dwarf primary has a strong magnetic field that radically affects the accretion flow in the system. → polar

magnetic; → cataclysmic; → binary.

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