An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 12948 Search : far
magnetic meridian
  نیمروزان ِ مغناتیسی   
nimruzân-e meqnâtisi

Fr.: méridien magnétique   

A meridian passing through the Earth's → magnetic poles.

magnetic; → meridian.

magnetic moment
  گشتاور ِ مغناتیسی   
gaštâvar-e meqnâtisi (#)

Fr.: moment magnétique   

1) A measure of the strength of a magnet or current-carrying coil. In the case of a bar magnet it is obtained by multiplying the distance between the two magnetic poles by the average strength of the poles. Same as → magnetic dipole moment See also → dipole moment.
2) A measure of the magnetic flux set up by the gyration of an electric charge in a magnetic field.
3) In atomic and nuclear physics, → spin magnetic moment.

magnetic; → moment.

magnetic monopole
  تک‌قطبه‌ی ِ مغناتیسی   
takqotbe-ye meqnâtisi (#)

Fr.: monopôle magnétique   

A hypothetical particle that carries a single → magnetic pole, in contrast to magnets which are north-south pole pairs. These massive particles (billions of times heavier than the → proton) are required by grand unified theories(→ GUTs) to explain the actual matter content of the Universe, particularly the dominance of matter upon → antimatter. However, their existence contradicts → Gauss's law for magnetism.

magnetic; → monopole.

magnetic monopole problem
  پراسه‌ی ِ تک‌قطبه‌ی ِ مغناتیسی   
parâse-ye takqotbe-ye meqnâtisi

Fr.: problème du monopôle magnétique   

A problem concerning the compatibility of grand unified theories (→ GUTs) with standard cosmology. If standard cosmology was combined with grand unified theories, far too many → magnetic monopoles would have been produced in the early Universe. The → inflation hypothesis aims at explaining the observed scarcity of monopoles. The inflation has deceased their density by a huge factor.

magnetic; → monopole; → problem.

magnetic needle
  سوزن ِ مغناتیسی   
suzan-e meqnâtisi

Fr.: aiguille aimantée   

A slender → magnet suspended in a magnetic compass on a mounting with little friction; used to indicate the direction of the Earth's → magnetic pole.

magnetic; → needle.

magnetic north pole
  قطب ِ هودر ِ مغناتیسی   
qotab-e hudar-e meqnâtisi

Fr.: pôle nord magnétique   

A point of the → magnetosphere where the Earth's → magnetic field points vertically downward; in other words it has a 90° → magnetic dip toward the Earth's surface. The magnetic north pole can also be defined as the point toward which the south pole of the → compass needle is directed. The magnetic north pole is different from the → geographic north pole. It is actually hundreds of kilometers south of the geographic north pole. However, this has not always been the case. In the past 150 years it has moved more than 1,000 kilometers. Every 200,000 to 300,000 years the magnetic field of the Earth reverses direction, → magnetic reversal. Since the Earth's magnetic field is not exactly symmetrical, the north and south magnetic poles are not → antipodal.

magnetic; → north; → pole.

magnetic null point
  نقطه‌ی ِ نول ِ مغناتیسی   
noqte-ye nul-e meqnâtisi

Fr.: point nul magnétique   

A region of the → solar corona where the → magnetic field vanishes.

magnetic; → null; → point.

magnetic permeability
  تراوایی ِ مغناتیسی   
tarâvâyi-ye meqnâtisi (#)

Fr.: perméabilité magnétique   

The ratio of the → magnetic induction, B, in the substance to the external magnetic field, H, causing the → induction: μ = B/H. It is measured in henry/meter and is known as absolute permeability. The relative permeability is equal to the ratio of absolute permeability to the permeability of the free space. Thus μr = μ/μ0, where μ0, the permeability of free space has the value 4π x 10-7 henry/meter.

magnetic; → permeability.

magnetic pole
  قطب ِ مغناتیسی   
qotb-e meqnâtisi (#)

Fr.: pôle magnétique   

1) The region of a magnet toward which the lines of magnetic force converge (south pole) or from which the lines of force diverge (north pole).
2) Either of the two points on the Earth's surface where the magnetic lines of force converge. They are not aligned with the geographical poles, but shift and do not lie exactly opposite of the other. → magnetic north pole, → magnetic south pole, → magnetic reversal.

magnetic; → pole.

magnetic Prandtl number
  عدد ِ پرانتل مغناتیسی   
adad-e Prandtl-e meqnâtisi

Fr.: nombre de Prandtl magnétique   

A → dimensionless quantity used in → magnetohydrodynamics to describe the relative balance of → kinematic viscosity to → magnetic diffusion. It is described by: Pr = σμ0ν = ν/η, where σ is the → conductivity of the fluid, μ0 is the → magnetic permeability of the fluid, ν is the kinematic viscosity of the fluid, and η is the → magnetic diffusivity.

magnetic; → Prandtl number.

magnetic pressure
  فشار ِ مغناتیسی   
fešâr-e meqnâtisi (#)

Fr.: pression magnétique   

The pressure exerted by a magnetic field on the material that contains the field.

magnetic; → pressure.

magnetic quantum number
  عدد ِ کو‌آنتومی ِ مغناتیسی   
adad-e kuântomi-ye meqnâtisi (#)

Fr.: nombre quantique magnétique   

In atomic physics, a quantum number that denotes the energy levels available within a subshell. Designated by the letter m, it is one of a set of quantum numbers which describe the unique quantum state of an electron.

magnetic; → quantum; → number.

magnetic reconnection
  بازهابند ِ مغناتیسی   
bâzhâband-e meqnâtisi

Fr.: reconnexion magnétique   

In a → plasma, a change of → magnetic connectivity of plasma elements due to the presence of a localized → diffusion region. It allows charged particles to move from one → magnetic field line to another. Magnetic reconnection is an important process transforming magnetic energy into heat or/and kinetic energy. Magnetic reconnection events occur in the Earth's → magnetosphere. The process plays an important role in explosive phenomena in the Sun, such as → coronal mass ejections and → solar flares which heat the → solar corona.

magnetic; → re-; → connection.

magnetic relaxation
  واهلش ِ مغناتیسی   
vâheleš meqnâtisi

Fr.: relaxation magnétique   

The process by which a magnetic system relaxes to its minimum energy state over time.

magnetic; → relaxation.

magnetic resonance
  بازاوایی ِ مغناتیسی   
bâzâvâyi-ye meqnâtisi (#)

Fr.: résonance magnétique   

A phenomenon exhibited by certain atoms whereby they absorb energy at specific (resonant) frequencies when subjected to alternating magnetic fields.

magnetic; → resonance.

magnetic reversal
  وارونش ِ مغناتیسی   
vâruneš-e meqnâtisi

Fr.: inversion magnétique   

A change in the Earth's → magnetic field in which the → magnetic north pole is transformed into a → magnetic south pole and the magnetic south pole becomes a magnetic north pole. There are geological proofs indicating that the Earth's magnetic field has undergone numerous reversals of → polarity in the past. In the last 10 million years, there have been, on average, 4 or 5 reversals per million years. At other times, for example during the → Cretaceous era, there have been much longer periods when no reversals occurred. Over the past two centuries, Earth's magnetic field has weakened by 15%. Risks of a weak magnetic field include more deaths from cancer due to increased radiation, electrical grid collapse from severe solar storms, climate change, and temporary ozone holes. See also → geomagnetic excursion.

magnetic; → reversal.

magnetic Reynolds number
  عدد ِ رینولدز ِ مغناتیسی   
adad-e Reynolds-e meqnâtisi

Fr.: nombre de Reynolds magnétique   

A → dimensionless quantity used in → magnetohydrodynamics to describe the relative balance of → magnetic advection to → magnetic diffusion. It is given by: Rm = σμ0νLU0, where σ is the → conductivity of the fluid, μ0 is the → magnetic permeability of the fluid, L is he characteristic length scale of the fluid flow, and U0 the characteristic velocity of the flow. A typical value for the Earth is Rm ~ 200.

magnetic; → Reynolds number.

magnetic rigidity
  سخت‌پایی ِ مغناتیسی   
saxtpâyi-ye meqnâtisi

Fr.: rigidité magnétique   

In → plasma physics, a → quantity that describes the → resistance of a → charged particle to change its direction of motion under the influence of a perpendicular → magnetic field. Rigidity is defined as: R = rLBc = (pc)/(Ze), where rL is the → Larmor radius, B is → magnetic induction, c is the → speed of light, p is the → momentum of the particle, Z is → atomic number, and e the → electron charge. Since pc has the dimensions of energy and e the dimensions of charge, rigidity has the dimensions of → volts (a 10 GeV proton has a rigidity of 10 GV). In → cosmic ray studies, the energies of cosmic rays are often quoted in terms of their rigidities, rather than their energies per nucleon.

magnetic; → rigidity.

magnetic south pole
  قطب ِ دشتر ِ مغناتیسی   
qotab-e daštar-e meqnâtisi

Fr.: pôle sud magnétique   

The → counterpart of the → magnetic north pole. It lies near the → geographic north pole.

magnetic; → south; → pole.

magnetic splitting
  فاقش ِ مغناتیسی   
fâqeš-e meqnâtisi

Fr.: dédoublement magnétique   

A process whereby the (internal) → magnetic field of a star modifies the → pulsations by lifting some of its degeneracy. Instead of just one pulsation frequency, a multiplet of frequencies is then observed. This effect was proposed as a possible explanation for the observed frequency pattern of → Beta Cephei. In practice, the magnetic splitting is difficult to observe, because of the very small expected frequency difference between the peaks. However, when unaccounted for, it may lead to a wrong mode identification. The current best candidate to detect magnetic splitting is → HD 43317, since this star displays two close frequency patterns (Buysschaert et al., 2017, astro-ph/1709.02619).

magnetic; → splitting.

<< < -es -iv -ti 21- A r abe abs abs acc acc acc act act ada adi adu aff age alc Alf ali all alp alt ama amp ana ang ang ann ano ant ant ape apo app aps arc Arg ari art ass ast ast ast atm ato att aur aut axi B r bac Bal Bar Bar Bay bec Ber Bet Bie bij bin bio bis bla bla blu blu bol Bor bou Bra bre bro Bug C-s cal Cam can car Car Cas cat cav cel cen cer Cha cha cha che cho cir cir cir cla clo clo clu coa coe coh col col col com com com com com com com com com con con con con con con con con con con con coo cor cor cor cos cos cos Cou cou Cra Cre cri cro cub cur cyc cyl dar dat daw de- Deb dec dec dee def deg del Den dep der det deu dew dic dif dif dil dip dir dis dis dis dis dis div dog Dop dou dra dua dus dwa dyn e-m ear ecl eco eff ein Ein elb ele ele ele ele Els emi emp ene enr env epi equ equ Eri est Euc eva evo exc exc exh exo exp exp ext ext f-n Fah fam fau fee Fer fib fil fin fir fix fle flu foc for for for fra fre fre fri fun fuz gal gal gal Gan gau GCN gen geo geo geo geo Gl glo gra gra gra gra gra gre gro GW1 hab hal han HAR haz hea hel hel Hen Her heu Hig Hil hol hop hor hou Hub Hum Hyd hyd hyd hyp hys ide ign ima imp imp inc inc ind ine inf inf inf inh INP ins ins int int int int Int int int int inv ion iri irr iso iso iso Jea Jos Jun K2 Kep key kin Kol lag lam Lan lar las lav lea leg len lev lig lim lin lin lin lis lob loc log lor low lum lun lun Lym Mac mag mag mag mag mag mai Mal mar mas mas mat max mea mea mee Men mer met met met mic mid Mil min Mir mix mod mod mol mon Mor mou mul muo mys nan nat nav nec Nep neu New New NGC nob nom non non nor not nuc nuc num Nyq obj obs obs oce oen OH omn opa ope opt opt opt orb ord Ori ort osc out ove oxy pal pan par Par par par pas pea Pen per per per per per pet pha pho pho pho phy pie Pit Pla pla pla pla ple Poi pol pol pol pol pop pos pos pow pre pre pre Pre pri pri pri pro pro pro pro pro pro Pro pub pul pyr qua qua qua qua Qui rad rad rad rad rad rad ram ran rat rea rec rec rec red ref ref reg reg rel rel rem rep res res res ret rev rho Rie rim riv rol Ros rot rul S a Sah san Sat sca Sch Sch scr sec sec sec sei sel sem sep set sha she sho sid sig sil sim sin sit sky slu sno sof sol sol sol sol sou sou spa spa spe spe spe sph spi spl spr sta sta sta sta sta ste ste sti sto str str sub sub sub sug sun sup sup sup sup sur syl syn sys tal Tay tel ten ter tex the the the thi tho thu tid tim tod top tot tra tra tra tra tri tri tro tru tur twi Typ UFO ult unc uni uni uni upg ura uti val var vec vel ver ver vig vir vis voc von wak Was wav wax wea wei whi Wie win WN6 wom X-r yel you zer zod > >>