An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 726
Rosette Nebula
  میغ ِ گلسان   
miq-e golsân

Fr.: nébuleuse de la Rosette   

A giant H II region of about 1° in diameter, lying about 5000 light-years away in the Milky Way, the constellation → Monoceros. It is ionized by the cluster NGC 2244, a group of hot young stars at the center of the nebula. Also called M16, the brighter portions of the nebula have been assigned different NGC numbers: 2237, 2238, 2239, and 2246.

Rosette "a rose-shaped ornament," from Fr. rosette, from O.Fr. rosette, diminutive of rose "rose;" L. rosa, probably from Gk. wrodon (Aeolic), then rhodon, a loan from Iranian, as below; → nebula.

Miq, → nebula; golsân "resembling rose, flower," from gol "flower, rose," variants vard (sohre-vard "red rose"), Semnâni dialect vela "rose;" Mid.Pers. *vard, gul, loaned in Arm. vard and Ar. ward; Av. varəδa- "rose;" loaned in Gk. wrodon (Aeolic), then rhodon; + -sân "manner, semblance" (variant sun, Mid.Pers. sân "manner, kind," Sogdian šôné "career").

Ross 128
  راس ۱۲۸   
Ross 128

Fr.: Ross 128   

A → red dwarf star of → spectral type M4. Other designations: Proxima Virginis, FY Virginis, GJ 447, HIP 57548, and LHS 315. With a distance of just 3.4 → parsecs, it is one of the brightest representatives of this subclass (V = 11.15, J = 6.51, H =5.95, K = 5.65 mag). It is the 13th closest (sub-)stellar system to the Sun, including → brown dwarfs. Ross 128 is moving toward us and will actually become our closest neighbor in just 71,000 years from now. Ross 128 has an → effective temperature, Teff = 3192, a mass of 0.168 Msun (→ solar mass), a → luminosity of 0.00362 Lsun (→ solar luminosity), a radius of 0.017 Rsun (→ solar radius), and a → metallicity [Fe/H] of -0.02. An Earth-sized → exoplanet, → R 128 b, orbits Ross 128 (Bonfils et al., 2017, arXiv:1711.06177).

Star number 128 in the → Ross Catalogue.

Ross 128 b
     
Ross 128 b

Fr.: Ross 128 b   

An → extrasolar planet around the → red dwarf star → R 128. The → exoplanet orbits its star every 9.9 days. This Earth-sized world is expected to be temperate, with a surface temperature that may also be close to that of the Earth. Many red dwarf stars, including → Proxima Centauri, are subject to → flares that occasionally bathe their orbiting planets in deadly → ultraviolet and → X-ray radiation. However, it seems that Ross 128 is a much quieter star, and so its planets may be the closest known comfortable abode for possible life. Ross 128 b orbits 20 times closer than the Earth orbits the Sun. Despite this proximity, it receives only 1.38 times more irradiation than the Earth. As a result, Ross 128 b's equilibrium temperature is estimated to lie between -60 and 20°C, thanks to the cool and faint nature of its small red dwarf host star, which has just over half the surface temperature of the Sun.

The letter b, designates the first exoplanet discovered around → R 128.

Ross catalogue
  کاتالوگ ِ راس   
kâtâlog-e Ross

Fr.: Catalogue de Ross   

Ross, Frank E., 1926, "New proper-motion stars, (second list)", Astronomical Journal 36, 856.

Frank Elmore Ross (1874-1960) was the succeeded to E. E. Barnard at Yerkes Observatory. He inheriting Barnard's collection of photographic plates. Ross decided to repeat the same series of images and compare the results with a → blink comparator. He discovered 379 new variable stars and over 1000 stars of high proper motion.

Rossby number
  عدد ِ رسبی   
'adad-e Rossby

Fr.: nombre de Rossby   

A dimensionless number relating the ratio of inertial to Coriolis forces for a given flow of a rotating fluid. It is used in the study of atmospheric motions in planets. In case a small number is involved, cyclones and anticyclones are observed for low and high pressures. When it is large (Venus) the Coriolis force becomes negligible and atmospheric motions are barely affected by planetary rotation.

Named after Carl-Gustav Arvid Rossby (1898-1957), a Swedish-American meteorologist who first explained the large-scale motions of the atmosphere in terms of fluid mechanics; → number.

Rossby parameter
  پارامون ِ روسبی   
pârâmun-e Rossby

Fr.: paramètre de Rossby   

The northward variation of the Coriolis parameter, arising from the sphericity of the Earth.

Rossby number; → parameter.

Rossby wave
  موج ِ روسبی   
mowj-e Rossby

Fr.: onde de Rossby   

A wave on a uniform current in a two-dimensional non-divergent fluid system, rotating with varying angular speed about the local vertical.

Rossby number; → wave.

Rosseland mean opacity
  کدری ِ میانگین ِ روسلاند   
kederi-ye miyângin-e Rosseland

Fr.: opacité moyenne de Rosseland   

The → opacity of a gas of given composition, temperature, and density averaged over the various wavelengths of the radiation being absorbed and scattered. The radiation is assumed to be in → thermal equilibrium with the gas, and hence have a → blackbody spectrum. Since → monochromatic opacity in stellar plasma has a complex frequency dependence, the Rosseland mean opacity facilitates the analysis. Denoted κR, it is defined by: 1/κR = (π/4σT3) ∫(1/kν) (∂B/∂T)νdν, summed from 0 to ∞, where σ is the → Stefan-Boltzmann constant, T temperature, B(T,ν) the → Planck function, and kν monochromatic opacity (See Rogers, F.J., Iglesias, C. A. Radiative atomic Rosseland mean opacity tables, 1992, ApJS 79, 507).

Named after Svein Rosseland (1894-1985), a Norwegian astrophysicist, who obtained the expression in 1924; → mean; → opacity.

Rossiter-McLaughlin effect
  اُسکر ِ راسیتر-مک‌لاکلین   
oskar-e Rossiter-McLaughlin

Fr.: effet Rossiter-McLaughlin   

A → spectroscopic phenomenon observed when either an → eclipsing binary's → secondary star or an → extrasolar planet is seen to → transit across the face of the → primary body. Because of the rotation of the star, an asymmetric distortion takes place in the → line profiles of the stellar spectrum, which changes during the transit. The measurement of this effect can be used to derive the → alignment of the → orbit of the transiting exoplanet with respect to the → rotation axis of the star.

Named after Richard Alfred Rossiter (1886-1977) and Dean Benjamin McLaughlin (1901-1965), American astronomers.

rotate
  چرخیدن   
carxidan (#)

Fr.: tourner   

To turn around an axis. See also → revolve.

From L. rotare "to cause to spin, roll, move in a circle," from L. rota "wheel;" cognate with Pers. râh "way, path" (from Mid.Pers. râh, râs "way, street," also rah, ras "chariot;" from Proto-Iranian *rāθa-; cf. Av. raθa- "chariot;" Skt. rátha- "car, chariot," rathyā- "road;" Lith. ratas "wheel;" O.H.G. rad; Ger. Rad; Du. rad; O.Ir. roth; PIE *roto- "to run, to turn, to roll").

Carxidan "to rotate," from carx "every thing performing a circulatory motion; a wheel; a cart;" Mid.Pers. chr "wheel," Parthian cxr "wheel;" Ossetic calx "wheel;" Av. caxra- "wheel;" cognate with Skt. cakra- "wheel, circle; cycle," carati "he moves, wanders;" Gk. kyklos "circle, wheel," polos "axis of a sphere," polein "move around;" L. colere "to dwell in, to cultivate, move around," colonus "farmer, settler;" O.E. hweol "wheel;" Rus. koleso "wheel."

rotating
  چرخنده، چرخان   
carxandé, carxân

Fr.: en rotation   

Capable of or having rotation.

From → rotate + → -ing.

rotating black hole
  سیه‌چال ِ چرخان   
siyahcâl-e carxân

Fr.: trou noir en rotation   

A black hole that possesses angular momentum, as first postulated by Roy C. Kerr in 1963. Opposite of a stationary black hole. → ergosphere.

rotating; → black hole.

rotating star
  ستاره‌ی ِ چرخان، ~ چرخنده   
setâre-ye carxân, ~ carxandé

Fr.: étoile en rotation   

A star that has a non-zero → angular velocity. In a rotating star, the → centrifugal forces reduce the → effective gravity according to the latitude and also introduce deviations from sphericity. In a rotating star, the equations of stellar structure need to be modified. The usual spherical coordinates must be replaced by new coordinates characterizing the → equipotentials. See also → von Zeipel theorem.

rotating; → star.

rotation
  چرخش   
carxeš (#)

Fr.: rotation   

The motion of a body about its axis.

Verbal noun of → rotate.

rotation axis
  آسه‌ی ِ چرخش   
âse-ye carxeš

Fr.: axe de rotation   

The imaginary line around which an object rotates. Same as → rotational axis and → axis of rotation.

rotation; → axis.

rotation curve
  خم ِ چرخش   
xam-e carxeš

Fr.: courbe de rotation   

A plot of the variation in → orbital velocity of stars and → interstellar matter with distance from the center of a → galaxy. A "flat" rotation curve indicates that the mass of the galaxy increases linearly with distance from its center. See also: farsi→ Keplerian rotation curve

Rotation; → curve.

rotation energy
  کاروژ ِ چرخش   
kâruž-e carxeš

Fr.: énergie de rotation   

The → kinetic energy of rotational motion of an object. It is expressed by ER = (1/2)Iω2, where I is the → moment of inertia and ω → angular velocity (2π/P).

rotation; → energy.

rotation frequency
  بسامد ِ چرخش   
basâmad-e carxeš

Fr.: fréquence de rotation   

1) The number of rotations per unit time of a rotating object.
2) The number of → stellar rotations per unit time. The reciprocal of the → rotation period. This parameter usually refers to the equator of the star, because stars do not rotate as solid bodies.

rotation; → frequency.

rotation period
  دوره‌ی ِ چرخش   
dowre-ye carxeš (#)

Fr.: période de rotation   

The interval of time during which an object turns once about its axis.

rotation; → period.

rotation phase
  فاز ِ چرخش   
fâz-e carxeš

Fr.: phase de rotation   

A position parameter used in → stellar magnetic field studies. Its zero value represents the moment when, during → stellar rotation, the positive → magnetic pole is nearest to the → line of sight.

rotation; → phase.

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