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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<< < -es -iv -ti 21- a p abe abs abs acc acc acc act act ada adi ads aes Age Alb Alf ali all alp alt ama amp ana ang ang ann ano ant ant ape apo app app arc Arg ari art ass ast ast ast atm ato att Aur aut axi azi bac Bal Bar Bar Bay Bec Ber bet bic bij bin bio Bir bla Bla blu blu bol Boo bou bra Bre bro bug C r cal Cal can car Car Cas cat cau cel cen cer Cha cha Cha che chl cir cir cir Cla cli clo clu co- coc coh col col col com com com com com com com com Com con con con con con con con con con con con con Cop Cor cor cor cos cos Cou cou cow cre cri cro cry cur cut Cyg dam dar dat de deb dec dec ded def deg del dem den dep des det dev dia dif dif dig dio Dir dis dis dis dis dis dis div don dou dow dro dur dwa dyn Dys ear ebb ecl edg egg Ein Ela ele ele ele ele ell eme emp enc eng ent epi equ equ Equ esc eth Eur eve exa exc exe exi exp exp ext ext eye fac fal Far fed fer fer fie fin fir fit fla flo flu fol for for Fou fra fre Fre fro fuz gai Gal Gal gam gas Gau gen gen geo geo geo gia glo gol gra gra gra gra gre gri gui H I hai Ham har Hau hea hec hel hel her HES hie hig his hom hor hot Hub hum Huy hyd hyd hyl hyp ice ide ima imp imp imp inc ind ind ine inf inf inf ini ins ins ins int int int int Int int int int inv ion iro irr iso iso ite jel Jou Jup kao Kep kil Kip Kra Lag Lam lan lar las law lea leg Leo lex lig lim lin lin lin lit Loc loc log Lor low lum lun lun Lym mac mag mag mag mag mag mai Mal mar mas mas mat max mea mec meg men mer met met met mic mic Mik min min mis mob mod mol mon moo mou mul mul mys nan Nat nau nec neo neu nev New NGC no nom non non nor not nuc nuc num nut obj obs obs occ odd OH Ome Oor ope opp opt opt orb ord ori ort osc out ove oxi pai Pan par par par par pas pea pen per per per per Per per pha phl pho pho pho pi pip Pla pla pla pla ple poa pol Pol pol pol pop pos pos pot pra pre pre pre pri pri pri pro pro pro pro pro pro pro Pto pul puz qua qua qua qua qui rad rad rad rad rad rad rai ran rar Ray rea Rea rec rec red red ref ref reg rel rel rel rep res res res res ret Rhe rid rig ris Roe Ros rot rub rut Sag sam sat sca sca Sch sci sea sec sec see sel sem sen ser Sh2 sha shi sho sid sig sim sin Sir ske sli Smo soc sol sol sol sol sol sou spa spa spe spe spe spe sph spi spo Squ sta sta sta sta ste ste ste sto str str str sub sub sub sum sup sup sup sup sur sus sym syn T d tap tec tem ten tes the the the the thi thr tid tim tip ton tor tow tra tra tra tra tri tri tru tub tur two Typ ult un- und uni uni unp upp urg V20 Van var veg vel ver vib vio vir vis Vol Vul wan wat wav WC4 wea wel whi Wil wis WNL wor X-r Yer Z s zer [C > >>

Number of Results: 12982 Search : far
21-centimeter line
  خط ِ ۲۱ س.م.   
xatt-e 21-sântimetr (#)

Fr.: raie 21-cm   

The → emission line of → neutral hydrogen in interstellar clouds. It lies in the radio spectrum at wavelength of about 21 cm, frequency 1420 MHz. Its existence was predicted by Hendrik van de Hulst in 1944 and discovered by Harold Ewen and Edward Purcell in 1951.

Twenty-one (21); → twenty + → one; → centimeter; → line.

2175 A bump
  قوز ِ 2175 آنگستروم   
quz-e 2175 Å

Fr.: bosse à 2175 Å   

The strongest spectral feature in the interstellar → extinction curve occurring in the → ultraviolet and centered at about 2175 Å. The feature is a strong function of the → metallicity of the gas. It appears slightly weaker in the → LMC extinction curve (metallicity about 50% solar), but essentially absent in the → SMC extinction curve (metallicity about 10% solar). Small → interstellar  → graphite  → dust grains or a mixture of graphite and → polycyclic aromatic hydrocarbons (PAHs) grains have been proposed in → dust models to explain the bump. However, at present the → carrier of the 2175 Å feature is basically unidentified.

angstrom; → bump.

25 Orionis
  ۲۵-شکارگر، ۲۵-اریون   
25-Šekârgar, 25-Oryon

Fr.: 25 Orionis   

A blue star of → apparent visual magnitude 4.96 lying in the → Orion constellation. It has other designations, including: ψ1 Orionis, BD+01 1005, HR 1789, and HIP 25302. 25 Ori is a → main sequence star of → spectral type B1 V. It lies at a distance of 1,040 → light-years and has a → luminosity of 9,300 MSun, a radius of 5.5 Rsun, and a mass of about 10 Msun. 25 Ori is in fact a → Be star.

25 Orionis group
  گروه ِ ۲۵-شکارگر، ~ ۲۵-اوریون   
goruh-e 25-Šekârgar, ~ 25-Oryon

Fr.: groupe de 25 Orionis   

A group of nearly 200 low-mass → pre-main-sequence stars, concentrated within ~ 1 of the early → B star  → 25 Orionis, in the component a of the → Orion OB1 Association. The group also harbors the → Herbig Ae/Be star V346 Ori and a dozen other early-type stars. The velocity distribution for the low-mass stars shows a narrow peak at 19.7 km s-1, offset ~ 10 km s-1 from the velocity characterizing the younger stars of the Ori OB1b subassociation, and 4 km s-1 from the velocity of widely spread young stars of the Ori OB1a population. This indicates that the 25 Ori group is a distinct kinematic entity. The low-mass members follow a well-defined band in the → color-magnitude diagram, consistent with an age of ~ 7-10 Myr (Briceno et al., 2007, ApJ 661, 1119).

25 Orionis; → group.

270 Anahita
  ۲۷۰ آناهیتا   
270 anâhitâ

Fr.: 270 Anahita   

A → main belt → S-type asteroid of size about 51 km. Its → semi-major axis is 2.198 → astronomical units and its orbital period 3.26 yr. It was discovered by C. H. F. Peters on October 8, 1887.

Name of an Iranian female deity, → Venus.

2I/Borisov
  ۲I/بوریسوف   
2I/Borisov

Fr.: 2I/Borisov   

A new → interstellar object of → cometary nature. Orbital and morphological properties of this body show that this is the first certain case of an interstellar comet, and the second-known interstellar minor body identified in the → Solar System (after → 1I/'Oumuamua). 2I/Borisov's motion shows significant systematic deviation from what is expected for a → parabolic orbit and is consistent with an enormous orbital → eccentricity of 3.14 ± 0.14. Images show an extended → coma and a faint, broad → tail. The → color index of 0.63 ± 0.03 is essentially the same as measured for the native Solar System → long-period comets. 2I/Borisov will reach its → perihelion on 7 December 2019, when it will be 2 → astronomical units (AU) from the Sun and also 2 AU from Earth. By January 2020 it will be at its brightest in the southern sky. It will then begin its outbound journey, eventually leaving the Solar System forever (Guzik et al., 2019, Nature Astronomy, 14 October).

Named after the amateur astronomer Gennady Borisov, from MARGO observatory, Crimea, who on 30 August 2019 discovered an object with a comet-like appearance.

30 Doradus
  ماهی ِ زرین ۳۰   
Mâhi-ye zarrin 30

Fr.: 30 Doradus   

Same as → Tarantula Nebula.

30 (→ thirty), the object number in the catalog of Johann Elert Bode (1747-1826) Allgemeine Beschreibung und Nachweisung der Gestirne nebst Verzeichniss, compiled in 1801; → Dorado.

3200 Phaethon
  ۳۲۰۰ فایتون   
3200 Phaeton

Fr.: 3200 Phaéton   

An → Apollo asteroid with unusual properties. Phaethon was discovered on October 11, 1983 using the → Infrared Astronomical Satellite. It is dynamically associated with the → Geminid meteor shower. Whereas most established → meteor shower parents are clearly → cometary in nature, the orbit of Phaethon is that of an → asteroid . Its → semi-major axis, → eccentricity, and → orbital inclination are a = 1.271 AU, e = 0.890, and i = 22.2, respectively, and the → Tisserand parameter with respect to → Jupiter is TJ = 4.5 (while the conventional → comets have TJ < 3). The → perihelion distance is remarkably small, q = 0.14 AU. Phaethon is roughly 5 km in diameter. Not to be confounded with → Phaeton.

Named after the Greek myth of Phaethon, son of the Sun god Helios, due to its close approach to our Sun.

3CR catalogue
  کاتالوگ ِ 3CR   
kâtâlog-e 3CR

Fr.: catalogue 3CR   

A catalog (Bennett, 1962) based on the original 3C survey (Edge et al., 1960) made at Cambridge at 159 MHz using a complex → interferometer system. This → survey was preceded by the 2C survey made with the same instrument at 81 MHz with a resolution two times poorer. The 2C catalog contained 1936 sources, but owing to the poor resolving power, it became clear at an early stage that many of these sources were not real, and were due to blends of two or more sources in the primary antenna beam. Moreover, except for the strongest sources, the determination of the flux density and angular coordinates was poor. The 3C survey contained only 471 sources and was considerably more reliable. Nevertheless, because of the relatively poor primary resolving power, there were still large errors in the positions and flux densities. In particular, it was frequently uncertain in which → lobe of the → interference pattern a particular source was located, and this introduced large positional uncertainties. In order to reduce these uncertainties an additional survey was made at 178 MHz using a large parabolic cylinder antenna. The narrow E-W beam of this antenna eliminated nearly all of the lobe ambiguities of the original 3C catalog. The data from the two surveys were combined to form the then most reliable radio source catalog - the Revised 3C or 3CR Catalogue. The same parabolic cylinder antenna was later used together with a smaller moveable antenna as an aperture synthesis instrument to make a complete high-resolution survey of the northern sky (the 4C survey), which contains about 2000 sources (NASA/IPAC Extragalactic Database, NED).

3, for the third "version;" C, for "catalog;" R, for "revised;" → catalog.

42 Orionis
  ۴۲-شکارگر، ۴۲-اریون   
42-Šekârgar, 42-Oryon

Fr.: 42 Orionis   

A blue star with → apparent visual magnitude 4.59 in → Orion's Sword. Also known as → c Orionis, HD 37018, HR 1892, and HIP 26237. More specifically, it is a → main sequence star of → spectral type B1 V, lying in the → H II regionNGC 1977. 42 Orionis is approximately 900 → light-years away based on parallax. It is the major source for ionizing photons in NGC 1977. 42 Ori is a → mutiple star system. The primary star, Aa, of magnitude 6.3 has a → companion companion Ab at a separation of 0.16'', and a more distant companion B of 7.5 magnitude at 1.6'' separation. An irradiated → circumstellar disk near 42 Ori has been detected by Bally et al. (2012) in the → HST image using Hα filter (F658N). They identified a bent → protostellar jet HH1064 from Parenago 2042 (the Spindle) in NGC 1977 with numerous → bow shock features. They argue that the arc feature in the Hα Spindle is centered on the star and its brightened side of the arc is facing toward 42 Ori, suggesting that it may be a → proplyd (Kim et al., 2016, arXiv::1606.08271).

Number 42 in → Flamsteed designation; Orionis, genitive of → Orion.

433 Eros
  ۴۳۳ اروس   
433 Eros

Fr.: 433 Eros   

An → S-type asteroid about 34.4 × 11.2 × 11.2 km in size, which is the second-largest → near-Earth asteroid after 1036 Ganymed. It belongs to the group of → Amor asteroids. Eros was discovered on 13 August 1898 by Gustav Witt in Berlin and Auguste Charlois at Nice. It was the first asteroid orbited by an Earth probe (in 2000).

Named after the Gk. god of love Eros.

44 Nysa
  ۴۴ نوسا   
44 Nusâ

Fr.: (44) Nysa   

The largest member of a rare class of → asteroids with a high surface → albedo, classified as an → E-type. It has an albedo of about 0.5, and is irregularly shaped, 113 × 67 × 65 km. Nysa has an → aphelion of 2.782 → astronomical units and a → perihelion of 2.064 AU. The → eccentricity is 0.15 with an → inclination of 3.70 degrees. The → orbital period is 1,378 days, or 3.77 years. It rotates in 6.42 h. The apparent magnitude ranges from 8.83 to 12.46. Nysa's orbit makes it the largest E-type asteroid inside Jupiter's resonance orbits. Nysa was discovered by Hermann Goldschmidt on May 27, 1857.

Named after the birthplace of Dionysus in Greek mythology.

47 Tucanae (NGC 104)
  ۴۷ توکان   
47 Tukân

Fr.: 47 Tucanae   

The second brightest → globular cluster, after → Omega Centauri. It is seen on the sky near the → Small Magellanic Cloud in the southern constellation → Tucana. Its apparent size is 31', about the size of the full Moon. It is about 13,000 → light-years away and contains several million stars in a volume only about 120 light-years across.

47, the object number in the catalog of Johann Elert Bode (1747-1826) Allgemeine Beschreibung und Nachweisung der Gestirne nebst Verzeichniss, compiled in 1801; → Tucana.

486958 Arrokoth
  ۴۸۶۹۵۸ اروکوت   
486958 Arrokoth

Fr.: (486958) Arrokoth   

A → trans-Neptunian object located in the → Kuiper belt; provisional designation 2014 MU69 and nicknamed Ultima Thule. Its overall dimensions are about 36 × 18 × 10 km. NASA's → New Horizons spacecraft conducted a close → flyby of the object on January 1, 2019 just 3,500 km above the object's surface. The images it took show that the object has in fact two distinct lobes. The individual lobes have approximate dimensions of 21 × 20 × 9 km and 15 × 14 × 10 km, respectively. At a → heliocentric distance of 44 → astronomical units, 486958 Arrokth is the most distant object ever visited by a spacecraft. It has an → orbital period of 298 years, a small → inclination (~ 2.45°), and a low → eccentricity (0.042).

Arrokoth is a Native American term meaning "sky" in the Powhatan language of the Tidewater region of Virginia and Maryland; → asteroid designation.

61 Cygni
  ۶۱ ماکیان   
61 Mâkiyân

Fr.: 61 Cygni   

A → binary star in the → constellation  → Cygnus lying at a distance of 11.4 → light-years. It consists of a pair of → K-type  → dwarf stars. The more massive component (61 Cygni A) is a K5 type with a mass of 0.70 Msun and the other one (61 Cygni B) a K7 type of 0.63 Msun. The components of this → visual binary orbit each other in a → period of about 659 years. 61 Cygni was the first star whose distance was measured using its → annual parallax. It was done by the German astronomer Friedrich Bessel in 1838 who derived a parallax of 0".314. Recent more precise observations with the → Hipparcos satellite give a value of 0".286. Same as → Bessel's star and → Piazzi's Flying Star.

61 Cygni, according to the → Flamsteed designation; → Cygnus.

8 Flora
  ۸ فلورا   
8 Flora

Fr.: (8) Flore   

A large, bright → main belt asteroid. With a diameter of 136 km, it is the innermost of large → asteroids and the largest member of the → Flora family. It revolves around the Sun with an → orbital period of 3.27 years between a → perihelion of 1.858 → astronomical units and an → aphelion of 2.546 AU. Flora was discovered by J. R. Hind on October 18, 1847.

The name Flora was proposed by John Herschel, from Flora, the Latin goddess of flowers and gardens, wife of Zephyrus (the personification of the West wind), and mother of Spring.

90482 Orcus
  ارکوس   
Orkus

Fr.: (90482) Orcus   

A → Kuiper belt object discovered in 2004. It has a large satellite named Vanth. Orcus is similar to → Quaoar in size and may be classified as a → dwarf planet.

Named for the ancient Roman god of the underworld, identified with the Greek Pluto, or Hades. The name was chosen because it shares a similar size, orbit, and orbital inclination to that of Pluto.

951 Gaspra
  ۹۵۱ گسپرا   
951 Gaspra

Fr.: (951) Gaspra   

An elongated → asteroid with dimensions of about 20 × 12 × 11 km. Gaspra is classified as an → S-type asteroid and is likely composed of metal-rich silicates and perhaps blocks of pure metal. It is a member of the → Flora family. It has a → rotation period of 7.04 hours. On October 29, 1991, the → Galileo spacecraft came within 1,600 km of Gaspra. They passed each other at 8 km/s. This was the first time that a spacecraft made a → flyby of an asteroid. Gaspra was discovered by Grigoriy N. Neujamin, Ukrainian astronomer, in 1916.

Named by its discoverer for a resort on the Crimean peninsula that was visited by contemporaries such as Tolstoy and Gorky.

mare
  دریانما   
daryânemâ

Fr.: mer   

An area on the surface of the → Moon that appears darker and smoother than its surroundings, once thought to be seas, now known to be lava-flooded basins; plural maria.

L. mare "sea," plural form maria, because Galileo thought the dark featureless areas on the Moon were bodies of water.

Daryânemâ literally "looking like a sea," from daryâ "sea" (Mid.Pers. daryâp variant zrah; O.Pers. drayah-; Av. zrayah- "sea;" cf. Skt. jráyas- "expanse, space, flat surface") + nemâ "looking, showing," present stem of nemudan "to show, display" (Mid.Pers. nimūdan, nimây- "to show," from O.Pers./Av. ni- "down; into," → ni-, + māy- "to measure," → display.

a posteriori
  افدوم   
afdom (#)

Fr.: à postériori   

1) Logic: Relating to or involving inductive reasoning from particular facts or effects to a general principle (dictionary.com).
2) Logic: Derived from or requiring evidence for its validation or support; empirical; open to revision (dictionary.com). → a priori.

L., literally "from what comes after," from posterior "after, later, behind," comparative of posterus "coming after, subsequent," from post "after," → post-.

Afdom "the last," Dehxodâ: afdom "last, end;" Mid.Pers. abdom, apdom; from Proto-Ir. *apatama- superlative of *apa- "away from, from;" cf. Av. apəma- "the last, the most distant;" Skt. apamá-.

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