An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 1002
Proxima Centauri
  پروکسیما کنتاؤروس، نزدیکترین ~   
proksimâ Kentâwros, nazdiktarin ~

Fr.: Proxima du Centaure   

The closest star to the Sun, lying 4.24 → light-years away. Other designations: α Centauri C, GL 551, HIP 70890, or simply Proxima. It is the faintest of the three stars that make up the → Alpha Centauri system. Proxima Centauri is a → red dwarf of → spectral type M6 Ve. It has a magnitude of +11.0, but undergoes sudden brightness increases of up to 1 mag lasting several minutes. Proxima is a late-type → flare star with a rotation period of ~ 84 days. Its mass is about 0.123 → solar masses or 129 → Jupiter masses. Proxima orbits the binary system AB at a distance of about 15,000 → astronomical unit (AU)s, with a period of approximately 550,000 years (Kervella et al., 2016, arXiv:1611.0349). In about 200,000 years it will be at the same distance as AB and in 240,000 years it will be farther to Sun than AB. It has an → effective temperature of only around 3,050 K, a luminosity of 0.15 per cent of that of the Sun, a measured radius of 14 per cent of the radius of the Sun and a mass of about 12 per cent of the mass of the Sun. An → exoplanet, named → Proxima b, has been discovered orbiting our nearest neighbor star. Proxima experiences a seven-year activity cycle, similar to the Sun's 11-year cycle (B. J. Wargelin, B. J. et al., 2016, arXiv:1610.03447). But unlike the Sun's relatively moderate flares, Proxima's outbursts of X-ray and ultraviolet radiation could prove deadly for any hypothetical life on its planet, Proxima b.

Proxima, feminine of proximus "nearest," superlative of prope "near;" → approximate; → Centaurus.

Proksimâ, from L., as above; Kentâwros, → Centaurus; nazdiktarin, superlative of nazdik "near," from Mid.Pers. nazdik "near," from nazd "close" (Mid.Pers. nazd, nazdik "near," nazdist "first;" O.Pers. ašna- "close;" Av. nazdišta- "nearest, next," nazdyo "nearer to," nas- "to come near, approach, reach;" cf. Skt. nédīyas- "closer, very close," nas- "to approach, to reach") + -ik, → -ic.

Proxima Centauri b
  پروکسیما کنتاؤروس b   
Proksimâ Kentâwros b

Fr.: Proxima Centauri b   

Proxima b.

Proxima Centauri

prussic acid
  اسید پروسیک   
asid prusik (#)

Fr.: acide prussique   

Same as → hydrogen cyanide (HCN).

So called because it was first obtained from Prussian blue, Fe7(CN)18.

Prutenic Tables
  زیج ِ پروسی   
zij-e Prusi

Fr.: Tables pruténiques   

A set of astronomical tables (→ ephemeris) created in 1551 by Erasmus Reinhold (1511-1553), professor of astronomy at Wittenberg, indicating the positions of the Sun, the Moon, and the planets on the basis of the → Copernican model of heliocentric solar system. They superseded the → Alfonsine Tables, but since circular orbits were used, they were no more accurate than those tables. They were themselves replaced by the → Rudolphine Tables.

From original L. title Tabulae prutenicae "Prussian Tables," such named because Albert I, Duke of Prussia, supported Reinhold and financed the printing; → table; → zij.

Przybylski's star
  ستاره‌ی ِ شبیلسکی   

Fr.: étoile de Przybylski   

A blue star, named HD 101065 or V816 Cen, with an extremely peculiar chemical composition and spectral features. Although the star has a surface temperature very close to that of stars with solar chemical composition, it displays some abundance anomalies typical of much hotter → Ap stars. The spectrum is dominated by a group of lines of → lanthanides, while in the spectra of normal stars with similar temperature the absorption lines of neutral elements from the iron group are predominant. The lanthanides may have abundances 103-104 times solar. The spectrum of Przybylski's star also shows the presence of radioactive → rare earth elements, such as → promethium and → technetium. Moreover, there are numerous strong absorption lines which defy identification. In some spectrum regions unidentified lines are more numerous than known lines. It is also a → roAp star (see, e.g., Gopka et al. 2008, Kinematics and Physics of Celestial Bodies Vol. 24, No. 2, 89).

Named after its discoverer, Antoni Przybylski (1961, Nature 189, 739).


Fr.: Psamathé   

A → retrograde irregular satellite of → Neptune discovered in 2003. Also known as Neptune X. According to preliminary estimates, it orbits Neptune at a distance of about 47 million km and takes almost 25 Earth years to make one orbit. It is about 38 kilometers in diameter.

In Gk. mythology, one of the Nereids, lover of Aeacus and mother of Phocus.


Fr.: pseudo-   

A combining form meaning "false, erroneous, pretended, unreal," used in the formation of compound words (pseudonym, pseudoclassic, pseudointellectual). In scientific use, denoting close or deceptive resemblance to the following element (pseudogene, pseudobulb, pseudocarp).
pseudo-disk, → pseudo-Euclidean space, → pseudo-nucleus, → pseudo-Riemannian space, → pseudoscience.

From Gk. pseudo-, combining form of pseudes "false," or pseudos "falsehood," both from pseudein "to lie, cheat, falsify."

Doruž-, from Mid.Pers. druž "false, untrue, deceptive" (Mod.Pers. doruq "lie"), drôzitan, druxtan "to lie;" O.Pers. drauga- "lie;" Av. drug- "to lie," družaiti "he lies, cheats;" cf. Skt. druhyati "he lies," drôha-, drôgha- "insult, injury," druh- "damage; ghost;" O.H.G. triogan "to deceive;" Ger. trügen "to deceive;" E. dream; PIE base *dhrugh- "to deceive, harm."


Fr.: pseudo-bulbe   

A general designation for both → box-peanut and → disk-like bulges. Although both, as opposed to the → classical bulges, show important rotational support, they also have different properties.

pseudo-; → bulge.


Fr.: pseudo-disque   

A mass structure around a → protostar that resembles an → accretion disk, but is in fact a simple flattened envelope.

pseudo-; → disk.

pseudo-Euclidean space
  فضای ِ دروژ-اقلیدوسی   
fazâ-ye doruž-Oqlidosi

Fr.: espace pseudo-euclidien   

A real vector space of dimension n having a symmetric bilinear form (x, y) such that in some basis e1, ..., en, the quadratic form (x2) takes the form x12 + ... + xn - 12 - xn2. Such bases are called orthonormal.

pseudo-; → Euclidean; → space.


Fr.: pseudo-noyau   

Same → false nucleus.

pseudo-; → nucleus.

pseudo-Riemannian space
  فضای ِ دروژ-ریمانی   
fazâ-ye doruž-Riemanni

Fr.: espace pseudo-riemannien   

A space with an affine connection (without torsion), at each point of which the tangent space is a → pseudo-Euclidean space (Encyclopedia of Mathematics, Kluwer Academic Publications, Editor in chief I. M. Vinogradov, 1991).

pseudo-; → Riemannian; → space.


Fr.: pseudonyme   

A fictitious name used by an author to conceal his or her identity; pen name (

pseudo-; → name.


Fr.: pseudoscience   

Any set of ideas, methods, or assertions that claims to be objective and scientific but that in fact does not seriously value or attempt to apply objectivity and → scientific method to its endeavors. Pseudoscientific statements are usually not → falsifiable by means of → objective experimental or observational evidence, in contrast to scientific statements that can be refuted. Pseudoscience uses scientific-sounding terminology but totally lacks scientific support. Among pseudoscience examples are → astrology, scientology, clairvoyance, and parapsychology.

pseudo-; → science.

Ptolemaic astronomy
  اخترشناسی ِ بتلمیوس، ~ بطلمیوس   
axtaršenâsi-ye Batlamyus (#)

Fr.: astronomie ptoléméenne   

Ptolemaic system.

Ptolemaic system; → astronomy.

Ptolemaic system
  راژمان ِ بتلمیوس، ~ بطلمیوس   
râžmân-e Batlamyus

Fr.: système de Ptolémée   

An empirical model developed by Ptolemy about 150 A.D., in which a motionless Earth was the center of the Universe. The Sun, Moon, and planets revolved around the Earth in → eccentric circles and → epicycles. The fixed stars were attached to an outer sphere concentric with Earth. The Ptolemaic system gave the positions of the planets accurately enough for naked-eye observations, although it also had serious defects. As an extreme example, according to Ptolemy's model for the Moon, our satellite should appear to be almost twice as large when it is full than it is at quadrature, which is an absurdity since it is not seen as such.

Claudius Ptolemaeus was a mathematician, geographer, astronomer, and astrologer. The most influential of Greek astronomers, he lived in Roman Egypt, and was probably born there; he died in Alexandria in 165 A.D.; → system.

  ۱) همگان؛ ۲) همگانی   
1) hamegân (#); 2) hamegâni (#)

Fr.: 1) public; 2) publique   

1a) The community or people in general.
1b) A particular group of people with a common interest, aim, etc.
2a) Of, relating to, or concerning the people as a whole.
2b) Open or accessible to all.
Related concepts: → all, → general, → omni-, → total, → universal.

M.E., from L. publicus "of the people; of the state," also "common, general, public; ordinary," and as a noun, "a commonwealth; public property," from Old L. poplicus "pertaining to the people." from populus "people."

Hamegân, from hamé, → all, + -gân suffix forming plural entities, from Mid.Pers. -gânag, -gâna.

public opinion
  پژان ِ همگانی   
pažân-e hamegâni

Fr.: opinion publique   

The collective opinion of many people on some issue, problem, etc., especially as a guide to action, decision, or the like (

public; → opinion.


Fr.: publication   

1) The act of publishing a book, periodical, map, piece of music, engraving, or the like.
2) The act of bringing before the public; announcement.
3) The state or fact of being published (

Verbal noun of → publish.


Fr.: publicité   

1) Extensive mention in the news media or by word of mouth or other means of communication.
2) The state of being public, or open to general observation or knowledge (

public; → -ity.

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