An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 712
merger process
  فراروند ِ تشک   
farâravand-e tašk

Fr.: processus de fusion   

The process of collision between galaxies which leads to a single galaxy.

merger; → process.

merger tree
  درخت ِ تشک   
deraxt-e tašk

Fr.: arbre de coalescence   

A method used in → numerical simulations for studying the growth and development of galaxies and → dark matter halos. Within the currently accepted ΛCDM cosmology, dark matter halos merge from small → clumps to ever larger structures. This merging history can be traced in simulations and stored in the form of merger trees. Merger trees are necessary because a galaxy may have more than one → progenitor at an early time.

merger; → tree.


Fr.: 1) fusion   

1) (n.) The act of joining together as one, such as galaxy → merger.
2) (adj.) That merges.

Noun from → merge.

merging galaxies
  کهکشان‌های ِ تشکنده   
kahkešânhâ-ye taškandé

Fr.: galaxies en coalescence   

Two or more galaxies that collide and merge into one galaxy.

merging; → galaxy.

nimruzân (#)

Fr.: méridien   

1) Geography: An imaginary line on the Earth's surface joining the north and south poles at right angles to the equator. See also → local meridian, → prime meridian.
2) Astron.: An imaginary great circle on the → celestial sphere that passes through its poles and the observer's → zenith.

M.E., from O.Fr. meridien, from L. meridianus "of noon, southern," from meridies "noon, south," from meridie "at noon," altered by dissimilation from *medi die, locative of medius "mid-" + dies "day."

Nimruzân, coined by Pers. astronomer (A.D. 973-1048) in his at-Tafhim, from nim "mid-, half" (Mid.Pers. nêm, nêmag "half;" Av. naēma- "half;" cf. Skt. néma- "half") + ruz, → day, + -ân suffix denoting time and place.

meridian angle
  زاویه‌ی ِ نیمروزان   
zâviye-ye nimruzân

Fr.: angle horaire   

Same as hour angle.

meridian; → angle.

meridian circle
  پرهون ِ نیمروزانی   
parhun-e nimruzâni

Fr.: circle méridien   

A telescope with a graduated vertical scale, used to measure the declinations of heavenly bodies and sometimes to determine the time of meridian transits.

meridian; → circle.

meridian instrument
  سازال ِ نیمروزانی   
sâzâl-e nimruzâni

Fr.: instrument méridien   

An instrument designed to observe objects when they cross the meridian.

meridian; → observation.

meridian observation
  نپاهش ِ نیمروزانی   
nepâheš-e nimruzâni

Fr.: observation au méridien   

The observation of a star when it crosses an observer's meridian.

meridian; → observation.

meridian passage
  گذر ِ نیمروزانی   
gozar-e nimruzâni

Fr.: passage au méridien   

The moment when a celestial object crosses an observer's meridian. Same as meridian transit.

meridian; → passage.


Fr.: méridien   

Of, pertaining to, or resembling a meridian.

meridian + → -al.

From nimruzân, → meridian, + -i adj. suffix.

meridional circulation
  پرهونش ِ نیمروزانی   
parhuneš-e nimruzâni

Fr.: circulation méridien   

The mass motion of material within a → rotating star generated by the star's departure from spherical symmetry. For a rotating star in which → centrifugal forces are not negligible, → radiative equilibrium and → hydrostatic equilibrium cannot be satisfied. In this condition energy transfer is accomplished by means of the physical motion of material. According to → von Zeipel theorem, the heating on an → equipotential surface is generally higher in the polar direction than in the equatorial direction, which drives a large scale circulation current rising at the pole and descending at the equator. As a consequence, → mixing of material takes place in the stellar interior; see also → Eddington-Sweet time scale. The meridional circulation plays an important role in the evolution of → massive stars. The circulation current was first suggested by Arthur S. Eddington in 1926 (The Internal Constitution of the Stars, Dover Pub. Inc., New York) and subsequently quantified by P. A. Sweet (1950, MNRAS 110, 548).

meridional; → circulation.

meridional flow
  تچان ِ نیمروزانی   
tacân-e nimruzâni

Fr.: courant méridien   

Meteo.: A flow between the poles, or between the equator and the poles. A positive value indicates flow away from the equator; a negative value, flow toward the equator.

meridional; → flow.

meridional magnetic field
  میدان ِ مغناتیسی ِ نیمروزانی   
meydân-e meqnâtisi-ye nimruzâni

Fr.: champ magnétiquue méridien   

In the → solar dynamo model, a magnetic field that points from the north to south or south to north.

meridional; → magnetic; → field.

Meropé (#)

Fr.: Mérope   

One of the stars in the Pleiades with a visual magnitude 4.17. It is a giant of spectral type B6 lying at a distance of about 1400 light-years.

Merope was one of the seven Pleiades, daughters of the Titan Atlas.

Mersenne prime
  نخست ِ مرسن   
naxost-e Mersenne

Fr.: nombre de Mersenne premier   

A → prime number of the form 2p - 1, where p is a prime. As of February 2013, 48 Mersenne primes are known. The largest known prime number is 257,885,161 - 1. Each prime gives rise to an even → perfect number.

Marin Mersenne (1588-1648), French theologian, philosopher, mathematician and music theorist; → prime.

Mesarthim (γ Arietis)

Fr.: Mésarthim   

A star of visual magnitude 4.8 lying 204 light-years away in the constellation → Aries. It is in fact a triple star system.

The origin of Mesarthim (or Mesartim) is a matter of controversy. Some scholars have related it to the Ar. methartim (مثرطم) "very fat (animal)," but the connection is not obvious although the words are apparently similar. The original Ar. name was Šaratayn (الشرطین) "the two marks" denoting the current β and γ stars in Aries. It was also the name of the lunar mansion of which these two stars were members. Johann Bayer (1572-1625) erroneously related Šaratayn to the Hebrew Sartai, a current term in the astrological literature of his time. Subsequently, others figured that Sartai was related to Hebrew Mesartim "servants." The Latin transliteration and alteration Mesarthim found much success in establishing itself as the proper name for star γ Arietis.


Fr.: maille, maillage   

1) One of the open spaces between the cords or ropes of a net.
2) Any knit, woven, or knotted fabric of open texture.
3) An interwoven or intertwined structure; network.
4) Electricity: A set of branches that forms a closed path in a network so that removal of a branch results in an open path. (

M.E. mesche "open space in a net," apparently from O.E. max "net," earlier mæscre (cf. Dan. maske, Sw. maska, M.Du. maessce, Du. maas "mesh," O.H.G. masca, Ger. Masche "mesh").

Bâncé "aperture, opening, window" in (Kermânšâhi) Kurd., ultimately from Proto-Ir. *banaka-, from *baH- "to shine," cf. Av. bāmya- "light, bright;" Pers. bâm "morning, dawn; splendor, light," Ossetic bon "day," probably related to bezel "opening, aperture," in several dialects of the Fârs province (Lâr, Gerâš, Xonj, Fišvar), → morning.


Fr.: meso-   

A combining form meaning "middle," used in the formation of compound words; e.g. → meson; → mesosphere.

From Gk. mesos "middle, in the middle;" akin to L. medius, Pers. miyân, → middle; → medium.

Meso-, loan from Gk.


Fr.: méson   

A nuclear particle with a mass intermediate between that of a proton and an electron, which is believed to be responsible for the strong nuclear force. In contrast to the case of baryons or leptons, meson number is not conserved: like photons, mesons can be created or destroyed in arbitrary numbers. Their charge can be positive, negative, or zero.

From mes-, meso-, from Gk. mesos "middle," akin to L. medius, Pers. miyân, → medium, → middle, + -on a suffix used in the names of subatomic particles.

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