An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 683
  ۱) تیر؛ ۲) جیوه، سیماب   
1) Tir; 2) jivé, simâb

Fr.: Mercure   

1) The closest → planet to the → Sun and one of five planets visible with the naked eye. It lies at a mean distance of about 0.39 → astronomical units from the Sun. Mercury is just 4,879 km in diameter, about 2.6 times smaller than the Earth. Its → orbital period is 87.97 Earth days. Mercury has a high → density, 5.4 g cm-3, with only the Earth having a higher density among the planets. This is largely due to Mercury being composed mainly of heavy metals and rock. One → solar day on Mercury lasts the equivalent of 176 Earth days while the sidereal day (the time for 1 rotation in relation to a fixed point) lasts 59 Earth days. Mercury is nearly → tidally locked to the Sun and over time this has slowed the rotation of the planet to almost match its orbit around the Sun. Mercury also has the highest orbital → eccentricity of all the planets with its distance from the Sun ranging from 46 to 70 million km. Mercury has just 38% the → gravity of Earth, this is too little to maintain an atmosphere against → solar winds, which blow it away. The surface of Mercury which faces the Sun has temperatures of up to 427°C, whilst on the alternate side this can be as low as -173°C. Mercury's core has more iron than any other planet in the → solar system. This has to do with its formation and early life. If the planet formed quickly, increasing temperatures of the evolving Sun could have vaporized much of the existing surface, leaving only a thin shell.
2) (lower case): Metallic chemical element, also called quicksilver; symbol Hg (from L. hydrargyrum "liquid silver"). → Atomic number 80; → atomic weight 200.59; → melting point -38.842°C; → boiling point 356.58°C. Mercury was first recognized as a chemical element (in the modern sense) by the French chemist Antoine L. Lavoisier (1743-1794).

From L. Mercurius "Mercury," the Roman god, originally a god of tradesmen and thieves, from merx "merchandise."

1) Mid.Pers. Tîr the name of the planet Mercury, O.Pers. proper noun *Tira-dāta- "given by Tir" (Hellenized Tiridates), Mid.Pers. Tîr.dât the name of three Parthian Kings; Av. Tīro.nakaθwa-.
2) Jivé, variant živé, from Mid.Pers. zivik, zivandag "alive, living," from zivastan "to live," zivižn "life;" O.Pers./Av. gay- "to live," Av. gaya- "life," gaeθâ- "being, world, mankind," jivya-, jva- "aliving, alive;" cf. Skt. jiva- "alive, living;" Gk. bios "life;" L. vivus "living, alive," vita "life;" O.E. cwic "alive;" E. quick; Lith. gyvas "living, alive;" PIE base *gweie- "to live."
Simâb "liquid silver," from sim "silver" (Mid.Pers. âsīm) + âb, → water.

  ۱) تشکیدن؛ ۲) تشکاندن   
1) taškidan; 2) taškândan

Fr.: fusionner   

1) (v.intr.) To become combined, united, swallowed up, or absorbed; lose identity by uniting or blending.
2) ( To cause to combine or coalesce. To combine, blend, or unite gradually so as to blur the individuality or individual identity of.
Related terms: → fuse, → coalesce. See also → merger, → mergeburst, → merger process, → merger tree, → merging, → merging galaxy, → minor merger, → mixed merger, → wet merger.

From L. mergere "to dip, immerse," probably rhotacized from *mezgo, and cognate with Skt. majj- "to dive, to sink," majjati "dives under;" Lith. mazgoju "to wash."

Taškidan, taškândan, from Gilaki tašk "tie, knot;" Tabari tešk "knot" + -idan infinitive suffix.



A hypothetical → transient event undergone by a → star due to its violent → merging with another star in a → close binary star. The release of → orbital energy causes the → envelope of the star to heat up and → inflate, causing the star to brighten considerably. Mergebursts are predicted to rival or exceed the brightest classical → novae in luminosity, but to be much cooler and redder than classical novae, and to become slowly hotter and bluer as they age.

merge; → burst.

  ۱) تشکه؛ ۲) تشک   
1) tašké; 2) tašk

Fr.: fusion, coalescence   

1) Any combination of two or more bodies into a single body. In particular, the formation of a galaxy from the collision of two or more separate galaxies.
2) An act or instance of merging.

From → merge + -er (as in waiver).

Tašké; tašk, nouns from taškidan, → merge.

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.

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