An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



<< < abs arg Cop dis Ham hyp int Mod per per per per per per pro Sma sup sup sup tem upp > >>

Number of Results: 419 Search : per

Fr.: interopérabilité   

The ability of different types of computers, networks, operating systems, and software applications to work together by exchanging and sharing information in a standardized, accurate, and effective manner.

inter-; → operability.

yašm (#)

Fr.: jaspe   

A colored form of natural silica, SiO2, which is a precious stone.

M.E. jaspe, jaspre, from M.Fr., O.Fr. jaspe, from L. iaspidem (nominative iaspis), from Gk. iaspis "jasper," via an Oriental language, probably an Eastern Iranian language, see below.

Yašm, variants, yasp, yasb, yašf "jasper;" Sogd. iešp "jasper," iešpênê "of jasper, crystalline."

kinetic temperature
  دمای ِ جنبشی   
damâ-ye jonbeši (#)

Fr.: température cinétique   

The temperature of a gas defined in terms of the average kinetic energy of its atoms or molecules.

kinetic; → temperature.

Kuiper belt
  کمربند ِ کویپر   
kamarband-e Kuiper (#)

Fr.: ceinture de Kuiper   

A region of the → Solar System extending roughly from the orbit of → Neptune, or 30 → astronomical units (AU), to 50 AU from the Sun that contains many small icy bodies. The Kuiper belt is now considered to be the source of the → short-period comets.

Named after Gerard Peter Kuiper (1905-1973), a Dutch-born American astronomer, who predicted the belt in 1951. He is also considered the father of modern planetary science for his contributions to the study of our solar system; → belt.

Kuiper belt object (KBO)
  بر‌آخت ِ کمربند ِ کویپر   
barâxt-e kamarband-e Kuiper

Fr.: objet de la ceinture de Kuiper   

A → Solar System object belonging to the → Kuiper belt. The largest known objects of this type are → Pluto and its moon → Charon, → Quaoar, → Sedna, and → Orcus. See also → trans-Neptunian object.

Kuiper belt; → object.

Laniakea supercluster
  ابرخوشه‌ی ِ لانیاکءا   
abarxuše-ye Laniakea

Fr.: superamas Laniakea   

A → supercluster of galaxies that includes our → Local Group and about 300 to 500 known → galaxy clusters and groups. Also called → Local Supercluster. If approximated as round, it has a diameter of 12,000 km s-1 in units of the → cosmic expansion or 160 megaparsecs, and encompasses about 1017 → solar masses. Our Local Group lies toward the outer regions of Laniakea. Its main components are the four previously known superclusters: → Virgo supercluster (the part where the → Milky Way resides), Hydra-Centaurus Supercluster (including the → Great Attractor, Antlia Wall, known as Hydra Supercluster, → Centaurus supercluster), Pavo-Indus Supercluster, and Southern Supercluster (including Fornax Cluster, Dorado and Eridanus clouds). The most massive galaxy clusters of Laniakea are Virgo, Hydra, Centaurus, Abell 3565, Abell 3574, Abell 3521, Fornax, Eridanus, and Norma. The Laniakea supercluster was discovered by Tully et al. (2014, Nature 513, 71).

From the Hawaiian words lani "heaven," and akea "spacious, immeasurable;" → supercluster.

Laplace operator
  آپارگر ِ لاپلاس   
âpârgar-e Laplace

Fr.: opérateur de Laplace   

Same as → Laplacian.

Laplace; → operator.

linear perturbation theory
  نگره‌ی ِ پرتورش ِ خطی   
negare-ye partureš-e xatti

Fr.: théorie de perturbation linéaire   

Assumption that the variations in the plasma parameters, due to the presence of waves, are small (to the first order) as compared to the undisturbed parameters. This makes it possible to linearize equations by dropping out second order (and higher) nonlinear terms.

linear; → perturbation; → theory.

Little Dipper
  هفت خواهران، چمچه‌ی ِ کوچک   
haft xâharân (#), camce-ye kucak (#)


An asterism in the constellation → Ursa Minor. This group of stars ends at → Polaris, the pole star of the Northern Hemisphere.

Little, from M.E., O.E. lytel, from W.Gmc. *lutila- (cf. Du. luttel, O.H.G. luzzil, Ger. lützel, Goth. leitils), from PIE *leud- "small;" dipper, from dip, O.E. dyppan "immerse," from P.Gmc. *dupjanan.

Haft xâharân "the seven sisters," from haft "seven" (Mid.Pers. haft; Av. hapta; cf. Skt. sapta; Gk. hepta; L. septem; P.Gmc. *sebun; Du. zeven; O.H.G. sibun; Ger. sieben; E. seven; PIE *septm) + xâharân plural of xâhar "sister;" Mid.Pers. xwâhar "sister;" Av. xvanhar- "sister;" cf. Skt. svásar- "sister;" Sogdian xwār; Gk. eor; L. soror (Fr. soeur); Arm. k'oyr; O.C.S., Rus. sestra; Lith. sesuo; O.Ir. siur; Welsh chwaer; M.Du. suster; Du. zuster; O.H.G. swester; Goth. swistar; Ger. Schwester; Swed. sister; Dan. søster; O.E. sweostor, swuster; E. sister.
Camcé "a spoon, ladle; a wooden bowl or cup;" kucak "small" (Mid.Pers. kucak "small"), related to kutâh "short, small, little," kudak "child, infant," kutulé, → dwarf, Mid.Pers. kôtâh "low," kôtak "small, young; baby;" Av. kutaka- "little, small").

Local Supercluster
  ا َبَرخوشه‌ی ِ محلی   
abarxuše-ye mahali (#)

Fr.: superamas local   

The supercluster to which the Local Group belongs. It is composed of some 100 clusters of galaxies, with the Virgo cluster of galaxies at its center.

local; → supercluster.

Lomb-Scargle periodogram
  دوره‌نگاشت ِ لومب-اسکارگل   
dowrenegâšt-e Lomb-Scargle

Fr.: périodogramme de Lomb-Scargle   

An algorithm for detecting and characterizing periodic signals in unevenly-sampled data. The Lomb-Scargle periodogram has a particularly wide use within the astronomy community. This method allows efficient computation of a Fourier-like → power spectrum estimator from such unevenly-sampled data, resulting in an intuitive means of determining the period of oscillation (see VanderPlas, 2017, astro-ph/1703.09824 and references therein).

Named after Lomb, N. R. 1976, Ap&SS 39, 447 and Scargle, J. D. 1982, ApJ 263, 835; → periodogram.

long-period comet
  دمدار ِ درازدوره   
domdâr-e derâz dowré

Fr.: comète à longue période   

A comet with orbital period of more than 200 years. → short-period comet; → periodic comet.

long; → period; → comet.

long-period variable
  ورتنده‌ی ِ درازدوره   
vartande-ye derâz dowré

Fr.: variable à longue période   

A type of → variable star in which variations in brightness occur over long time-scales of months or years. The term generally refers to → Mira variable types.

long; → period; → variable.

lunar sidereal orbital period
  دوره‌ی ِ مداری ِ اختری ِ مانگ   
dowre-ye madâri-ye axtari-ye mâng

Fr.: période orbitale sidérale de la Lune   

Same as → sidereal month.

lunar; → sidereal; → orbital; → period.

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.

method of small perturbations
  روش ِ پرتورش‌های ِ کوچک   
raveš-e parturešhâ-ye kucak

Fr.: méthode des petites perturbations   

The linearization of the appropriate equations governing a system by the assumption of a steady state, with departures from that steady state limited to small perturbations. Also called perturbation method.

method; → small; → perturbation.

Michelson-Morley experiment
  آزمایش ِ مایکلسون-مورلی   
âzmâyeš-e Michelson-Morley (#)

Fr.: expérience de Michelson-Morley   

An experiment performed in 1887 to establish the presence or absence of an → ether, a medium through which light was supposed to travel. The experiment aimed to measure the speed of light coming from different directions. However no → ether drift was found. The null results obtained showed that the ether hypothesis was incorrect. Consequently, the theory of → special relativity, with its hypothesis that the speed of light is the same in all → inertial frames, reconciled the results of the Michelson-Morley experiment with the rest of physics.

Michelson interferometer; Michelson received the Nobel Prize in 1907 for his work, the first American to receive the Prize in science. Edward Williams Morley (1838-1923), an American chemist; → experiment.

Miller-Urey experiment
  آزمایش ِ میلر-اوری   
âzmâyeš-e Miller-Urey

Fr.: expérience de Miller-Urey   

A chemical experiment conducted in 1953 that aimed at checking Alexander Oparin's and J. B. S. Haldane's hypothesis that under putative conditions present in the atmosphere of the early Earth inorganic molecules would spontaneously form organic molecules. Miller and Urey filled a sterile flask with a mixture of water, ammonia, methane, and hydrogen. The mixture was heated to evaporate water to produce water vapor. High-voltage electric sparks were passed through the mixture to simulate lightning. After a week, contents were analyzed. Amino acids, the building blocks for proteins, were found.

Named after Stanley L. Miller (1930-2007) and Harold C. Urey (1893-1981); → experiment.

Millikan's oil-drop experiment
  آزمایش ِ میلیکن   
âzmâyeš-e Millikan (#)

Fr.: expérience de Millikan   

A precision experiment for measuring the → electron charge. By studying the falling speed of small charged droplets in the gravitational field of the Earth subjected to an adjustable electric field, Millikan (1909) was able to demonstrate conclusively the discrete nature of electric charge, and moreover measure the charge of an individual electron.

Robert Andrews Millikan (1868-1953); → experiment.

Mirfak (α Persei)
Merfaq (#)

Fr.: Mirfak   

The brightest star of Perseus, with a visual magnitude of 1.8. It is a giant of spectral type F5 lying some 590 light-years away.

From Ar. al-Mirfaq (المرفق) "the elbow."

Merfaq, from Ar. al-Mirfaq, as above.

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